Title: WHO / GYN
Tags: GYN::Ovary::Neoplastic GYN::Uterus::Neoplastic GYN::Vulva::Neoplastic GYN::Cervix::Neoplastic GYN::Peritoneum::Neoplastic GYN::Vagina::Neoplastic GYN::Ovary::Congenital_Structural GYN::Cervix::Normal_Histology GYN::Cervix::Congenital_Structural GYN::Fallopian_Tube::Neoplastic GYN::Peritoneum::Congenital_Structural GYN::Uterus::Normal_Histology GYN::Fallopian_Tube::Congenital_Structural GYN::Uterus::Congenital_Structural GYN::Vagina::Congenital_Structural GYN::Fallopian_Tube::Inflammatory

Q: A characteristic histologic feature of Ependymoma is the presence of perivascular [...].
Ependymoma. Ependymal (perivascular) pseudorosettes.
A: pseudorosettes
Back Extra: Ependymoma
- Clinical: Patients with ependymoma often present with a pelvic mass and/or pain; serum CA125 may be elevated.
- Micro: Histologically, ependymoma shows columnar/cuboidal cells with eosinophilic cytoplasm, mild/moderate atypia, and a low mitotic count. Ependymal pseudorosettes are a characteristic feature.
- Ancillary: Immunohistochemical studies show positivity for GFAP, ER, PR, CK18, CK7, S100, and WT1.
Reference Gallery:
Ependymoma. Ependymal (perivascular) pseudorosettes.
Ependymoma. GFAP-positive staining in the neoplastic cells.

Q: Immunohistochemical staining in Ependymoma classically shows diffuse positivity for the glial marker [...].
Ependymoma. GFAP-positive staining in the neoplastic cells.
A: GFAP
Back Extra: Ependymoma
- Clinical: Patients with ependymoma often present with a pelvic mass and/or pain; serum CA125 may be elevated.
- Micro: Histologically, ependymoma shows columnar/cuboidal cells with eosinophilic cytoplasm, mild/moderate atypia, and a low mitotic count. Ependymal pseudorosettes are a characteristic feature.
- Ancillary: Immunohistochemical studies show positivity for GFAP, ER, PR, CK18, CK7, S100, and WT1.
Reference Gallery:
Ependymoma. Ependymal (perivascular) pseudorosettes.
Ependymoma. GFAP-positive staining in the neoplastic cells.

Q: Microscopic examination of a Nabothian Cyst typically reveals dilated, mucus-filled spaces lined by a single layer of benign [...] columnar or attenuated epithelium.
Nabothian cyst. Mucus-producing columnar cells similar to those of normal endocervical glandular cells lining cystically dilated spaces.
A: endocervical-type
Back Extra: Nabothian Cyst
- Clinical: Nabothian cysts are usually asymptomatic but can present as polyps or be associated with chronic cervicitis and mucous discharge.
- Micro: The cystic spaces are round to slightly irregular and lined by a single layer of non-atypical attenuated to columnar endocervical-type epithelium.
- Ancillary: Ancillary studies are not typically required for the diagnosis of Nabothian cysts.
Reference Gallery:
Nabothian cyst. Large cystically dilated and mucus-filled spaces beneath stratified squamous epithelium.
Nabothian cyst. Mucus-producing columnar cells similar to those of normal endocervical glandular cells lining cystically dilated spaces.

Q: A [...] is a common, typically asymptomatic cervical lesion that microscopically presents as large, mucus-filled cystic spaces located just beneath the stratified squamous epithelium.
Nabothian cyst. Large cystically dilated and mucus-filled spaces beneath stratified squamous epithelium.
A: Nabothian Cyst
Back Extra: Nabothian Cyst
- Clinical: Nabothian cysts are usually asymptomatic but can present as polyps or be associated with chronic cervicitis and mucous discharge.
- Micro: The cystic spaces are round to slightly irregular and lined by a single layer of non-atypical attenuated to columnar endocervical-type epithelium.
- Ancillary: Ancillary studies are not typically required for the diagnosis of Nabothian cysts.
Reference Gallery:
Nabothian cyst. Large cystically dilated and mucus-filled spaces beneath stratified squamous epithelium.
Nabothian cyst. Mucus-producing columnar cells similar to those of normal endocervical glandular cells lining cystically dilated spaces.

Q: Microscopically, Tunnel Clusters present as well-demarcated, rounded, lobular aggregates of closely packed [...] that can be small (non-cystic) or cystically dilated.
Tunnel cluster. A well-demarcated lesion composed of cystically dilated glands.
Tunnel cluster. Dilated glands lined by flattened or cuboidal mucus-producing cells.
A: endocervical-lined tubules
Back Extra: Tunnel Clusters
- Clinical: Tunnel clusters are usually asymptomatic but can occasionally cause a mucoid discharge. They are generally incidental findings that affect about 10% of adult women, usually multiparous.
- Micro: Tunnel clusters consist of rounded, lobular aggregates of closely packed endocervical-lined tubules of varying size. Non-cystic tunnel clusters show predominantly small glands, whereas cystic tunnel clusters show dilated glands.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of tunnel clusters.
Reference Gallery:
Tunnel cluster. A well-demarcated lesion composed of cystically dilated glands.
Tunnel cluster. Dilated glands lined by flattened or cuboidal mucus-producing cells.

Q: In cystic Tunnel Clusters, the dilated glands are characteristically lined by flattened or cuboidal [...].
Tunnel cluster. Dilated glands lined by flattened or cuboidal mucus-producing cells.
A: mucus-producing cells
Back Extra: Tunnel Clusters
- Clinical: Tunnel clusters are usually asymptomatic but can occasionally cause a mucoid discharge. They are generally incidental findings that affect about 10% of adult women, usually multiparous.
- Micro: Tunnel clusters consist of rounded, lobular aggregates of closely packed endocervical-lined tubules of varying size. Non-cystic tunnel clusters show predominantly small glands, whereas cystic tunnel clusters show dilated glands.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of tunnel clusters.
Reference Gallery:
Tunnel cluster. A well-demarcated lesion composed of cystically dilated glands.
Tunnel cluster. Dilated glands lined by flattened or cuboidal mucus-producing cells.

Q: The histologic diagnosis of [...] is characterized by a proliferation of glands within the lower female genital tract (e.g., cervical stroma) that are morphologically identical to normal male prostate glands, featuring a double layer of basal and luminal cells.
Ectopic prostate tissue. Glands that are morphologically identical to prostate glands in cervical stroma.
A: Ectopic Prostate Tissue
Back Extra: Ectopic Prostate Tissue
- Clinical: Patients are usually asymptomatic; rare cases present with vaginal bleeding and a visible lesion. Some cases occur in association with long-term testosterone therapy and other causes of increased androgens, such as adrenogenital syndrome.
- Micro: There is a proliferation of glands/tubules of variable size with a double layer of basal and luminal cells. The basal cells are flattened or cuboidal cells with scant cytoplasm, and the luminal cells are columnar cells with moderate amounts of clear, eosinophilic, or granular cytoplasm.
- Ancillary: Immunohistochemically, the luminal cells are variably positive for PSA, PAP, AMACR, and NKX3-1, and the basal cell layer is p63-positive; the glandular and squamous elements are AR-positive.
Reference Gallery:
Ectopic prostate tissue. Glands that are morphologically identical to prostate glands in cervical stroma.

Q: Microscopically, Endocervicosis is characterized by deeply located, often dilated glands lined by benign [...] cells.
Endocervicosis. Dilated glands identified in the outer portion of the cervix adjacent to parametrium.
Endocervicosis. Deeply located glands lined by mucus-producing columnar cells similar to those of normal endocervical glands.
A: mucus-producing columnar
Back Extra: Endocervicosis
- Clinical: Typically presents in reproductive-aged women with pelvic pain or may be asymptomatic.
- Micro: Characterized by variably sized and shaped glands, often dilated, involving the outer cervix, lined by benign endocervical-type epithelium.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of endocervicosis.
Reference Gallery:
Endocervicosis. Dilated glands identified in the outer portion of the cervix adjacent to parametrium.
Endocervicosis. Deeply located glands lined by mucus-producing columnar cells similar to those of normal endocervical glands.

Q: In Endocervicosis, the benign endocervical-type glands are characteristically found deeply located in the [...] or adjacent parametrium.
Endocervicosis. Dilated glands identified in the outer portion of the cervix adjacent to parametrium.
A: outer cervix
Back Extra: Endocervicosis
- Clinical: Typically presents in reproductive-aged women with pelvic pain or may be asymptomatic.
- Micro: Characterized by variably sized and shaped glands, often dilated, involving the outer cervix, lined by benign endocervical-type epithelium.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of endocervicosis.
Reference Gallery:
Endocervicosis. Dilated glands identified in the outer portion of the cervix adjacent to parametrium.
Endocervicosis. Deeply located glands lined by mucus-producing columnar cells similar to those of normal endocervical glands.

Q: In Endocervicosis of the vagina, the characteristic histologic finding deep within the vaginal stroma is the presence of variably sized glands lined by bland, [...] epithelium.
Vaginal endocervicosis. Vaginal endocervicosis is characterized by bland endocervical-type mucinous glands located deep in the vaginal stroma.
A: mucinous endocervical-type
Back Extra: Endocervicosis of the vagina
- Clinical: Endocervicosis of the vagina is an extremely rare lesion, with only two reports in the literature. One case presented with a painful vaginal mass.
- Micro: Endocervicosis is characterized by variably sized and shaped glands lined by bland mucinous endocervical-type epithelium, located deep within the vaginal stroma.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of endocervicosis of the vagina.
Reference Gallery:
Vaginal endocervicosis. Vaginal endocervicosis is characterized by bland endocervical-type mucinous glands located deep in the vaginal stroma.

Q: Microscopically, an Endocervical Polyp consists of fibrovascular tissue lined by benign [...] with glands permeating the central stroma.
Endocervical polyp. An example with pronounced cystic glands.
Endocervical polyp. An example with pronounced cystic glands.
A: endocervical-type epithelium
Back Extra: Endocervical Polyp
- Clinical: Endocervical polyp is usually asymptomatic but may present with vaginal bleeding, especially postcoital, and/or discharge.
- Micro: Endocervical polyps are composed of fibrovascular tissue lined by benign endocervical-type epithelium with glands permeating the central stroma.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of endocervical polyps.
Reference Gallery:
Endocervical polyp. An example with pronounced cystic glands.
Endocervical polyp. An example with pronounced cystic glands.
Endocervical polyp. An example with pronounced cystic glands (higher-power view of Fig. #18006).

Q: As prominently featured in some histologic sections, the glands permeating the fibrovascular stroma of an Endocervical Polyp can undergo pronounced [...] change.
Endocervical polyp. An example with pronounced cystic glands.
Endocervical polyp. An example with pronounced cystic glands (higher-power view of Fig. #18006).
A: cystic
Back Extra: Endocervical Polyp
- Clinical: Endocervical polyp is usually asymptomatic but may present with vaginal bleeding, especially postcoital, and/or discharge.
- Micro: Endocervical polyps are composed of fibrovascular tissue lined by benign endocervical-type epithelium with glands permeating the central stroma.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of endocervical polyps.
Reference Gallery:
Endocervical polyp. An example with pronounced cystic glands.
Endocervical polyp. An example with pronounced cystic glands.
Endocervical polyp. An example with pronounced cystic glands (higher-power view of Fig. #18006).

Q: Microscopically, Mesonephric Remnants and Hyperplasia classically present as simple tubules lined by bland cuboidal cells containing characteristic intraluminal [...].
Mesonephric remnant. Simple tubules lined by cuboidal cells with bland nuclei, usually with intraluminal eosinophilic secretions.
A: eosinophilic secretions
Back Extra: Mesonephric Remnants and Hyperplasia
- Clinical: Mesonephric remnants and hyperplasia are usually incidental findings, but hyperplasia may present with abnormal cervical cytology or as a mass.
- Micro: Mesonephric remnants consist of tubules lined by cuboidal cells with bland nuclei and eosinophilic secretions. Hyperplasia shows proliferations of these tubules, often in a lobular, diffuse, ductal, or mixed pattern.
- Ancillary: CD10, calretinin, GATA3, TTF1, and PAX8 are frequently positive in mesonephric remnants and hyperplasia, while ER/PR and p16 are negative.
Reference Gallery:
Mesonephric remnant. Simple tubules lined by cuboidal cells with bland nuclei, usually with intraluminal eosinophilic secretions.
Mesonephric hyperplasia, lobular type. The lesion shows rounded aggregates of mesonephric tubules.
Mesonephric hyperplasia, ductal type. The lesion shows a proliferation of small tubules surrounding a central duct.

Q: Rounded aggregates of small tubules (lobular pattern) or proliferations of small tubules surrounding a central duct (ductal pattern) are characteristic architectural features of [...].
Mesonephric hyperplasia, lobular type. The lesion shows rounded aggregates of mesonephric tubules.
Mesonephric hyperplasia, ductal type. The lesion shows a proliferation of small tubules surrounding a central duct.
A: Mesonephric Remnants and Hyperplasia
Back Extra: Mesonephric Remnants and Hyperplasia
- Clinical: Mesonephric remnants and hyperplasia are usually incidental findings, but hyperplasia may present with abnormal cervical cytology or as a mass.
- Micro: Mesonephric remnants consist of tubules lined by cuboidal cells with bland nuclei and eosinophilic secretions. Hyperplasia shows proliferations of these tubules, often in a lobular, diffuse, ductal, or mixed pattern.
- Ancillary: CD10, calretinin, GATA3, TTF1, and PAX8 are frequently positive in mesonephric remnants and hyperplasia, while ER/PR and p16 are negative.
Reference Gallery:
Mesonephric remnant. Simple tubules lined by cuboidal cells with bland nuclei, usually with intraluminal eosinophilic secretions.
Mesonephric hyperplasia, lobular type. The lesion shows rounded aggregates of mesonephric tubules.
Mesonephric hyperplasia, ductal type. The lesion shows a proliferation of small tubules surrounding a central duct.

Q: Microscopically, the presence of a superficially located, dense, and polymorphous lymphoid infiltrate containing numerous immunoblasts is characteristic of [...].
Reactive lymphoid hyperplasia. Dense superficial lymphoid infiltrate is characteristic.
Reactive lymphoid hyperplasia. High-power view shows numerous immunoblasts.
A: Florid Reactive Lymphoid Hyperplasia
Back Extra: Florid Reactive Lymphoid Hyperplasia
- Clinical: Florid reactive lymphoid hyperplasia almost always occurs in premenopausal women and may present with vaginal or postcoital bleeding.
- Micro: The lesion is superficially located and composed of a polymorphous infiltrate of lymphoid cells, including immunoblasts, plasma cells, and neutrophils.
- Ancillary: Immunostaining reveals a mixture of B cells, T cells, and polytypic plasma cells, but ancillary studies are not clinically relevant for diagnosis.
Reference Gallery:
Reactive lymphoid hyperplasia. Dense superficial lymphoid infiltrate is characteristic.
Reactive lymphoid hyperplasia. High-power view shows numerous immunoblasts.
Reactive lymphoid hyperplasia of endometrium. Endometrial tissue with dense atypical lymphoid infiltrate, characteristic of reactive lymphoid hyperplasia.

Q: In a premenopausal woman presenting with vaginal bleeding, an endometrial biopsy showing a dense, atypical lymphoid infiltrate is highly suggestive of [...].
Reactive lymphoid hyperplasia of endometrium. Endometrial tissue with dense atypical lymphoid infiltrate, characteristic of reactive lymphoid hyperplasia.
A: Florid Reactive Lymphoid Hyperplasia
Back Extra: Florid Reactive Lymphoid Hyperplasia
- Clinical: Florid reactive lymphoid hyperplasia almost always occurs in premenopausal women and may present with vaginal or postcoital bleeding.
- Micro: The lesion is superficially located and composed of a polymorphous infiltrate of lymphoid cells, including immunoblasts, plasma cells, and neutrophils.
- Ancillary: Immunostaining reveals a mixture of B cells, T cells, and polytypic plasma cells, but ancillary studies are not clinically relevant for diagnosis.
Reference Gallery:
Reactive lymphoid hyperplasia. Dense superficial lymphoid infiltrate is characteristic.
Reactive lymphoid hyperplasia. High-power view shows numerous immunoblasts.
Reactive lymphoid hyperplasia of endometrium. Endometrial tissue with dense atypical lymphoid infiltrate, characteristic of reactive lymphoid hyperplasia.

Q: Histologically, Diffuse Laminar Endocervical Hyperplasia features a well-demarcated, [...] proliferation of irregularly shaped, angulated, or star-shaped glands.
Diffuse laminar endocervical hyperplasia. Well-delineated laminar proliferation of irregularly shaped endocervical glands with associated inflammation.
A: laminar
Back Extra: Diffuse Laminar Endocervical Hyperplasia
- Clinical: Patients may present with mucoid watery discharge, over a wide age range, with a mean patient age in the fourth decade of life.
- Micro: There is a well-demarcated diffuse proliferation of typically round to oval but often irregular, angulated, or star-shaped endocervical glands with a dense acute and chronic inflammatory infiltrate.
- Ancillary: Ancillary studies are not clinically relevant.
Reference Gallery:
Diffuse laminar endocervical hyperplasia. Well-delineated laminar proliferation of irregularly shaped endocervical glands with associated inflammation.
Diffuse laminar endocervical hyperplasia. Reactive nuclear enlargement with chromatin clearing and nucleoli may be seen in association with periglandular stromal oedema and chronic inflammation.

Q: In Diffuse Laminar Endocervical Hyperplasia, the stroma surrounding the hyperplastic glands typically demonstrates chronic inflammation and prominent periglandular [...].
Diffuse laminar endocervical hyperplasia. Reactive nuclear enlargement with chromatin clearing and nucleoli may be seen in association with periglandular stromal oedema and chronic inflammation.
A: edema
Back Extra: Diffuse Laminar Endocervical Hyperplasia
- Clinical: Patients may present with mucoid watery discharge, over a wide age range, with a mean patient age in the fourth decade of life.
- Micro: There is a well-demarcated diffuse proliferation of typically round to oval but often irregular, angulated, or star-shaped endocervical glands with a dense acute and chronic inflammatory infiltrate.
- Ancillary: Ancillary studies are not clinically relevant.
Reference Gallery:
Diffuse laminar endocervical hyperplasia. Well-delineated laminar proliferation of irregularly shaped endocervical glands with associated inflammation.
Diffuse laminar endocervical hyperplasia. Reactive nuclear enlargement with chromatin clearing and nucleoli may be seen in association with periglandular stromal oedema and chronic inflammation.

Q: Microscopically, Lobular Endocervical Glandular Hyperplasia is classically characterized by a central [...] surrounded by a lobular proliferation of small to medium-sized glands.
Lobular endocervical glandular hyperplasia. A central cleft is surrounded by a lobular proliferation of small to medium-sized glands.
A: cleft-like space
Back Extra: Lobular Endocervical Glandular Hyperplasia
- Clinical: Patients with lobular endocervical glandular hyperplasia may present with mucoid watery discharge, and the condition typically affects reproductive-age women.
- Micro: Lobular endocervical glandular hyperplasia is characterized by a central cleft-like space surrounded by a lobular proliferation of small to medium-sized glands with tall columnar mucinous epithelium.
- Ancillary: Genetic mutations in GNAS (42%), KRAS (5%), and STK11 (10%) can be seen in lobular endocervical glandular hyperplasia, but these are not clinically relevant for diagnosis.
Reference Gallery:
Lobular endocervical glandular hyperplasia. A central cleft is surrounded by a lobular proliferation of small to medium-sized glands.
Lobular endocervical glandular hyperplasia. Glands are lined by tall columnar mucinous epithelium with bland, basally located nuclei.
Lobular endocervical glandular hyperplasia. Atypical lobular endocervical glandular hyperplasia. Architectural atypia and nuclear atypia are required for diagnosis.

Q: In Lobular Endocervical Glandular Hyperplasia, the proliferating glands are typically lined by tall columnar [...] with bland, basally located nuclei.
Lobular endocervical glandular hyperplasia. Glands are lined by tall columnar mucinous epithelium with bland, basally located nuclei.
A: mucinous epithelium
Back Extra: Lobular Endocervical Glandular Hyperplasia
- Clinical: Patients with lobular endocervical glandular hyperplasia may present with mucoid watery discharge, and the condition typically affects reproductive-age women.
- Micro: Lobular endocervical glandular hyperplasia is characterized by a central cleft-like space surrounded by a lobular proliferation of small to medium-sized glands with tall columnar mucinous epithelium.
- Ancillary: Genetic mutations in GNAS (42%), KRAS (5%), and STK11 (10%) can be seen in lobular endocervical glandular hyperplasia, but these are not clinically relevant for diagnosis.
Reference Gallery:
Lobular endocervical glandular hyperplasia. A central cleft is surrounded by a lobular proliferation of small to medium-sized glands.
Lobular endocervical glandular hyperplasia. Glands are lined by tall columnar mucinous epithelium with bland, basally located nuclei.
Lobular endocervical glandular hyperplasia. Atypical lobular endocervical glandular hyperplasia. Architectural atypia and nuclear atypia are required for diagnosis.

Q: To diagnose the atypical variant of Lobular Endocervical Glandular Hyperplasia, pathologists must identify both architectural and [...] atypia.
Lobular endocervical glandular hyperplasia. Atypical lobular endocervical glandular hyperplasia. Architectural atypia and nuclear atypia are required for diagnosis.
A: nuclear
Back Extra: Lobular Endocervical Glandular Hyperplasia
- Clinical: Patients with lobular endocervical glandular hyperplasia may present with mucoid watery discharge, and the condition typically affects reproductive-age women.
- Micro: Lobular endocervical glandular hyperplasia is characterized by a central cleft-like space surrounded by a lobular proliferation of small to medium-sized glands with tall columnar mucinous epithelium.
- Ancillary: Genetic mutations in GNAS (42%), KRAS (5%), and STK11 (10%) can be seen in lobular endocervical glandular hyperplasia, but these are not clinically relevant for diagnosis.
Reference Gallery:
Lobular endocervical glandular hyperplasia. A central cleft is surrounded by a lobular proliferation of small to medium-sized glands.
Lobular endocervical glandular hyperplasia. Glands are lined by tall columnar mucinous epithelium with bland, basally located nuclei.
Lobular endocervical glandular hyperplasia. Atypical lobular endocervical glandular hyperplasia. Architectural atypia and nuclear atypia are required for diagnosis.

Q: Histologically, microglandular hyperplasia features clusters of crowded mucinous glands that frequently demonstrate prominent [...] along with reserve cell hyperplasia.
Microglandular hyperplasia. The mucinous cells show subnuclear vacuoles and there is associated reserve cell hyperplasia along the base. Some glands show luminal neutrophils.
A: subnuclear vacuoles
Back Extra: Microglandular Hyperplasia
- Clinical: Microglandular hyperplasia is usually an incidental finding, or it may present with contact bleeding, and is typically identified in women of reproductive age, often associated with pregnancy and progestogen therapy.
- Micro: There are clusters of crowded small glands lined by cuboidal to columnar mucinous epithelium, with subnuclear vacuolation and reserve cell hyperplasia often present. The nuclei are uniform, with absent or scant mitoses.
- Ancillary: Immunohistochemistry is not necessary for diagnosis, but the glandular epithelium is usually positive for ER, PAX2, and cyclin D1 and negative for p16, vimentin, and CEA, with a Ki-67 proliferation index of < 10%.
Reference Gallery:
Microglandular hyperplasia. Closely packed variably sized glands lined by mucinous epithelium are separated by scant, focally inflamed stroma.
Microglandular hyperplasia. The mucinous cells show subnuclear vacuoles and there is associated reserve cell hyperplasia along the base. Some glands show luminal neutrophils.

Q: The benign cervical lesion shown in the images, characterized by closely packed mucinous glands, luminal neutrophils, and an absence of significant atypia or mitoses, is [...].
Microglandular hyperplasia. Closely packed variably sized glands lined by mucinous epithelium are separated by scant, focally inflamed stroma.
Microglandular hyperplasia. The mucinous cells show subnuclear vacuoles and there is associated reserve cell hyperplasia along the base. Some glands show luminal neutrophils.
A: microglandular hyperplasia
Back Extra: Microglandular Hyperplasia
- Clinical: Microglandular hyperplasia is usually an incidental finding, or it may present with contact bleeding, and is typically identified in women of reproductive age, often associated with pregnancy and progestogen therapy.
- Micro: There are clusters of crowded small glands lined by cuboidal to columnar mucinous epithelium, with subnuclear vacuolation and reserve cell hyperplasia often present. The nuclei are uniform, with absent or scant mitoses.
- Ancillary: Immunohistochemistry is not necessary for diagnosis, but the glandular epithelium is usually positive for ER, PAX2, and cyclin D1 and negative for p16, vimentin, and CEA, with a Ki-67 proliferation index of < 10%.
Reference Gallery:
Microglandular hyperplasia. Closely packed variably sized glands lined by mucinous epithelium are separated by scant, focally inflamed stroma.
Microglandular hyperplasia. The mucinous cells show subnuclear vacuoles and there is associated reserve cell hyperplasia along the base. Some glands show luminal neutrophils.

Q: Histologically, Müllerian Papilloma is characterized by finely branching [...] lined by a single layer of benign cuboidal to columnar epithelial cells.
Müllerian papilloma. The lesion is composed of finely branching fibrous papillae lined by a single layer of cuboidal to columnar epithelial cells.
A: fibrous papillae
Back Extra: Müllerian Papilloma
- Clinical: Müllerian papilloma is associated with vaginal bleeding or discharge and occurs almost exclusively in children, typically aged 2–5 years.
- Micro: Finely branching fibrous papillae are lined by a single layer of benign cuboidal to columnar epithelial cells. Squamous metaplasia or hobnail-type cells may be present, but cytology is bland without atypia.
- Ancillary: Ancillary studies are not clinically relevant for Müllerian papilloma.
Reference Gallery:
Müllerian papilloma. The lesion is composed of finely branching fibrous papillae lined by a single layer of cuboidal to columnar epithelial cells.

Q: Clinically, Müllerian Papilloma classically presents with vaginal bleeding or discharge and occurs almost exclusively in [...] (typically aged 2–5 years).
Müllerian papilloma. The lesion is composed of finely branching fibrous papillae lined by a single layer of cuboidal to columnar epithelial cells.
A: young children
Back Extra: Müllerian Papilloma
- Clinical: Müllerian papilloma is associated with vaginal bleeding or discharge and occurs almost exclusively in children, typically aged 2–5 years.
- Micro: Finely branching fibrous papillae are lined by a single layer of benign cuboidal to columnar epithelial cells. Squamous metaplasia or hobnail-type cells may be present, but cytology is bland without atypia.
- Ancillary: Ancillary studies are not clinically relevant for Müllerian papilloma.
Reference Gallery:
Müllerian papilloma. The lesion is composed of finely branching fibrous papillae lined by a single layer of cuboidal to columnar epithelial cells.

Q: Histologically, [...] is characterized by small, bland, rounded nests of monomorphic basaloid cells with central cystic change or glandular differentiation, typically lacking a significant stromal reaction.
Adenoid basal carcinoma. This tumour shows a proliferation of small rounded nests of basaloid cells with some glandular differentiation. This case also shows overlying high-grade squamous intraepithelial lesion.
Adenoid basal carcinoma composed of nests of bland basaloid cells with central cystic change. There is a lack of significant stromal reaction to the tumour nests.
A: Adenoid Basal Carcinoma
Back Extra: Adenoid Basal Carcinoma
- Clinical: Patients are generally asymptomatic and the tumour is usually discovered incidentally during management of an abnormal Pap test结果.
- Micro: Small, bland, well-differentiated, rounded nests or cords of monomorphic basaloid cells with scant cytoplasm and peripheral palisading, cystic change, or glandular/squamous differentiation.
- Ancillary: Tumour cells are positive for broad-spectrum cytokeratins, p63, and p16; high-risk HPV is commonly detected.
Reference Gallery:
Adenoid basal carcinoma. This tumour shows a proliferation of small rounded nests of basaloid cells with some glandular differentiation. This case also shows overlying high-grade squamous intraepithelial lesion.
Adenoid basal carcinoma composed of nests of bland basaloid cells with central cystic change. There is a lack of significant stromal reaction to the tumour nests.

Q: Because patients with Adenoid Basal Carcinoma are generally asymptomatic, the tumor is often discovered incidentally during the workup of an abnormal Pap test, frequently alongside an overlying [...] (HSIL).
Adenoid basal carcinoma. This tumour shows a proliferation of small rounded nests of basaloid cells with some glandular differentiation. This case also shows overlying high-grade squamous intraepithelial lesion.
A: high-grade squamous intraepithelial lesion
Back Extra: Adenoid Basal Carcinoma
- Clinical: Patients are generally asymptomatic and the tumour is usually discovered incidentally during management of an abnormal Pap test结果.
- Micro: Small, bland, well-differentiated, rounded nests or cords of monomorphic basaloid cells with scant cytoplasm and peripheral palisading, cystic change, or glandular/squamous differentiation.
- Ancillary: Tumour cells are positive for broad-spectrum cytokeratins, p63, and p16; high-risk HPV is commonly detected.
Reference Gallery:
Adenoid basal carcinoma. This tumour shows a proliferation of small rounded nests of basaloid cells with some glandular differentiation. This case also shows overlying high-grade squamous intraepithelial lesion.
Adenoid basal carcinoma composed of nests of bland basaloid cells with central cystic change. There is a lack of significant stromal reaction to the tumour nests.

Q: In the mesonephric variant of Carcinosarcoma of the uterine cervix, histologic examination reveals a biphasic tumor consisting of a relatively low-grade epithelial component admixed with a high-grade [...] component.
Carcinosarcoma, mesonephric type. Tumour composed of a relatively low-grade–appearing epithelial component admixed with a high-grade sarcomatous component. Areas of typical mesonephric carcinoma were present (not shown).
A: sarcomatous
Back Extra: Carcinosarcoma of the uterine cervix
- Clinical: Cervical carcinosarcoma occurs mostly in postmenopausal women and presents as a large polypoid mass protruding from the cervical os.
- Micro: The carcinomatous component can be represented by a subtype seen in primary cervical epithelial malignancy, and the mesenchymal component is often homologous but can occasionally show heterologous differentiation.
- Ancillary: The epithelial component is positive for CD10 and GATA3, and an osteosarcoma component can be confirmed with SATB2.
Reference Gallery:
Carcinosarcoma, mesonephric type. Tumour composed of a relatively low-grade–appearing epithelial component admixed with a high-grade sarcomatous component. Areas of typical mesonephric carcinoma were present (not shown).

Q: Histologically, a cervical tumor demonstrating deep wall invasion and composed of tubules and glands lined by a monolayer of cuboidal cells set within a myxohyaline stroma is highly characteristic of [...].
Clear cell carcinoma of cervix, HPV-independent. The tumour invades into the inner portion of the cervical wall.
Clear cell carcinoma of cervix, HPV-independent. Tubules and glands lined by a monolayer of cuboidal cells with uniform nuclei are present in myxohyaline stroma.
A: Clear Cell Adenocarcinoma, HPV-independent, of the Uterine Cervix
Back Extra: Clear Cell Adenocarcinoma, HPV-independent, of the Uterine Cervix
- Clinical: Clear cell adenocarcinomas of the cervix are rare, accounting for 3–4% of cervical adenocarcinomas, and can occur as sporadic tumours or in association with in utero diethylstilbestrol (DES) exposure.
- Micro: The tumour cells are arranged in a tubulocystic, papillary, and/or solid architecture, with clear or eosinophilic cytoplasm, prominent cytoplasmic boundaries, and hyperchromatic nuclei.
- Ancillary: Immunohistochemically, the tumours can be diffusely positive for p16 despite an absence of high-risk HPV infection, and are usually negative for ER and GATA3.
Reference Gallery:
Clear cell carcinoma of cervix, HPV-independent. The tumour invades into the inner portion of the cervical wall.
Clear cell carcinoma of cervix, HPV-independent. Tubules and glands lined by a monolayer of cuboidal cells with uniform nuclei are present in myxohyaline stroma.

Q: A key architectural and stromal feature of Clear Cell Adenocarcinoma, HPV-independent, of the Uterine Cervix is the presence of cuboidal to clear tumor cells arranged in a tubulocystic, papillary, or solid pattern, often embedded within a distinct [...] stroma.
Clear cell carcinoma of cervix, HPV-independent. Tubules and glands lined by a monolayer of cuboidal cells with uniform nuclei are present in myxohyaline stroma.
A: myxohyaline
Back Extra: Clear Cell Adenocarcinoma, HPV-independent, of the Uterine Cervix
- Clinical: Clear cell adenocarcinomas of the cervix are rare, accounting for 3–4% of cervical adenocarcinomas, and can occur as sporadic tumours or in association with in utero diethylstilbestrol (DES) exposure.
- Micro: The tumour cells are arranged in a tubulocystic, papillary, and/or solid architecture, with clear or eosinophilic cytoplasm, prominent cytoplasmic boundaries, and hyperchromatic nuclei.
- Ancillary: Immunohistochemically, the tumours can be diffusely positive for p16 despite an absence of high-risk HPV infection, and are usually negative for ER and GATA3.
Reference Gallery:
Clear cell carcinoma of cervix, HPV-independent. The tumour invades into the inner portion of the cervical wall.
Clear cell carcinoma of cervix, HPV-independent. Tubules and glands lined by a monolayer of cuboidal cells with uniform nuclei are present in myxohyaline stroma.

Q: [...] is a rare primary endocervical neoplasm that presents with well-formed glands, bland vesicular nuclei, and a characteristic negativity for p16 and high-risk HPV.
Endometrioid adenocarcinoma of cervix. High-power view of endometrioid adenocarcinoma of cervix composed of well-formed glands, tumour-infiltrating lymphocytes, round open vesicular nuclei, and minimal mitoses or apoptotic bodies. HPV mRNA in situ hybridization and p16 were negative (not shown).
A: Endometrioid Adenocarcinoma of the Uterine Cervix
Back Extra: Endometrioid Adenocarcinoma of the Uterine Cervix
- Clinical: Primary endometrioid adenocarcinoma of the cervix is rare, accounting for no more than 1% of all primary endocervical adenocarcinomas. Symptoms may include vaginal bleeding and nonspecific pelvic symptoms.
- Micro: The endometrioid subtype must present confirmatory endometrioid features: at least focal low-grade endometrioid glands lined by columnar cells with light eosinophilic cytoplasm and pseudostratified bland nuclei.
- Ancillary: HPV negativity is a key finding, and ancillary studies may include p16 and/or mRNA-based high-risk HPV in situ hybridization to ascertain HPV-associated status.
Reference Gallery:
Endometrioid adenocarcinoma of cervix. High-power view of endometrioid adenocarcinoma of cervix composed of well-formed glands, tumour-infiltrating lymphocytes, round open vesicular nuclei, and minimal mitoses or apoptotic bodies. HPV mRNA in situ hybridization and p16 were negative (not shown).

Q: Endometrioid Adenocarcinoma of the Uterine Cervix (pictured) features low-grade endometrioid glands with tumor-infiltrating lymphocytes; an essential ancillary finding is its negativity for [...].
Endometrioid adenocarcinoma of cervix. High-power view of endometrioid adenocarcinoma of cervix composed of well-formed glands, tumour-infiltrating lymphocytes, round open vesicular nuclei, and minimal mitoses or apoptotic bodies. HPV mRNA in situ hybridization and p16 were negative (not shown).
A: human papillomavirus (HPV)
Back Extra: Endometrioid Adenocarcinoma of the Uterine Cervix
- Clinical: Primary endometrioid adenocarcinoma of the cervix is rare, accounting for no more than 1% of all primary endocervical adenocarcinomas. Symptoms may include vaginal bleeding and nonspecific pelvic symptoms.
- Micro: The endometrioid subtype must present confirmatory endometrioid features: at least focal low-grade endometrioid glands lined by columnar cells with light eosinophilic cytoplasm and pseudostratified bland nuclei.
- Ancillary: HPV negativity is a key finding, and ancillary studies may include p16 and/or mRNA-based high-risk HPV in situ hybridization to ascertain HPV-associated status.
Reference Gallery:
Endometrioid adenocarcinoma of cervix. High-power view of endometrioid adenocarcinoma of cervix composed of well-formed glands, tumour-infiltrating lymphocytes, round open vesicular nuclei, and minimal mitoses or apoptotic bodies. HPV mRNA in situ hybridization and p16 were negative (not shown).

Q: On histology, Epithelioid Trophoblastic Tumor forms nests and cords containing characteristic [...] material, which can mimic keratinizing squamous cell carcinoma.
Epithelioid trophoblastic tumour. Eosinophilic hyaline-like material within tumour cell nests may simulate keratinizing squamous cell carcinoma.
A: eosinophilic hyaline-like
Back Extra: Epithelioid Trophoblastic Tumour
- Clinical: Vaginal bleeding is the most common symptom, and serum hCG is mildly to moderately elevated in 80% of cases.
- Micro: Tumour cells form nests or cords with eosinophilic hyaline-like material and extensive necrosis.
- Ancillary: Diffuse expression of p63 and Ki-67 proliferation index > 10%.
Reference Gallery:
Epithelioid trophoblastic tumour. There is a destructive nodular mass lesion.
Epithelioid trophoblastic tumour. There is a proliferation of relatively uniform cells with geographical tumour cell necrosis.
Epithelioid trophoblastic tumour. There is often calcification.
Epithelioid trophoblastic tumour. Tumour cells colonizing cervical mucosal epithelium may simulate a high-grade squamous intraepithelial lesion.
Epithelioid trophoblastic tumour. Eosinophilic hyaline-like material within tumour cell nests may simulate keratinizing squamous cell carcinoma.
Epithelioid trophoblastic tumour. Presence of decidualized benign stromal cells around tumour nests.
Epithelioid trophoblastic tumour. Diffuse expression of p63 in tumour cells.
Epithelioid trophoblastic tumour. Ki-67 proliferation index of > 10%.
Epithelioid trophoblastic tumour. A 49-year-old woman (gravida 4 para 4) presented with vaginal bleeding and a large mass measuring 12.2 × 8.7 × 8.5 cm, involving the uterus and cervix. Serum β-hCG at presentation was 24,310 IU/L. She received 7 cycles of chemotherapy, and within 6 months there was a dramatic reduction in the size (3.7 cm) of the lesion, and serum β-hCG dropped to 6 IU/L. Hysterectomy with bilateral salpingo-oophorectomy was performed. A homogenous tan-grey tumour measuring 35 mm in maximum dimension is present in the anterior lower uterine segment, extending to the cervix with a peripheral rim of yellowish-brown necrosis. Histologically, the tumour cells invade beyond the macroscopic confines of the visible tumour mass and extend to < 1 mm from the parametrial/paracervical margin.

Q: Immunohistochemical staining for Epithelioid Trophoblastic Tumor characteristically demonstrates diffuse expression of [...], as well as a Ki-67 proliferation index > 10%.
Epithelioid trophoblastic tumour. Diffuse expression of p63 in tumour cells.
Epithelioid trophoblastic tumour. Ki-67 proliferation index of > 10%.
A: p63
Back Extra: Epithelioid Trophoblastic Tumour
- Clinical: Vaginal bleeding is the most common symptom, and serum hCG is mildly to moderately elevated in 80% of cases.
- Micro: Tumour cells form nests or cords with eosinophilic hyaline-like material and extensive necrosis.
- Ancillary: Diffuse expression of p63 and Ki-67 proliferation index > 10%.
Reference Gallery:
Epithelioid trophoblastic tumour. There is a destructive nodular mass lesion.
Epithelioid trophoblastic tumour. There is a proliferation of relatively uniform cells with geographical tumour cell necrosis.
Epithelioid trophoblastic tumour. There is often calcification.
Epithelioid trophoblastic tumour. Tumour cells colonizing cervical mucosal epithelium may simulate a high-grade squamous intraepithelial lesion.
Epithelioid trophoblastic tumour. Eosinophilic hyaline-like material within tumour cell nests may simulate keratinizing squamous cell carcinoma.
Epithelioid trophoblastic tumour. Presence of decidualized benign stromal cells around tumour nests.
Epithelioid trophoblastic tumour. Diffuse expression of p63 in tumour cells.
Epithelioid trophoblastic tumour. Ki-67 proliferation index of > 10%.
Epithelioid trophoblastic tumour. A 49-year-old woman (gravida 4 para 4) presented with vaginal bleeding and a large mass measuring 12.2 × 8.7 × 8.5 cm, involving the uterus and cervix. Serum β-hCG at presentation was 24,310 IU/L. She received 7 cycles of chemotherapy, and within 6 months there was a dramatic reduction in the size (3.7 cm) of the lesion, and serum β-hCG dropped to 6 IU/L. Hysterectomy with bilateral salpingo-oophorectomy was performed. A homogenous tan-grey tumour measuring 35 mm in maximum dimension is present in the anterior lower uterine segment, extending to the cervix with a peripheral rim of yellowish-brown necrosis. Histologically, the tumour cells invade beyond the macroscopic confines of the visible tumour mass and extend to < 1 mm from the parametrial/paracervical margin.

Q: A characteristic microscopic finding in Epithelioid Trophoblastic Tumor is a proliferation of relatively uniform cells with distinct geographical [...] and frequent calcifications.
Epithelioid trophoblastic tumour. There is a proliferation of relatively uniform cells with geographical tumour cell necrosis.
Epithelioid trophoblastic tumour. There is often calcification.
A: necrosis
Back Extra: Epithelioid Trophoblastic Tumour
- Clinical: Vaginal bleeding is the most common symptom, and serum hCG is mildly to moderately elevated in 80% of cases.
- Micro: Tumour cells form nests or cords with eosinophilic hyaline-like material and extensive necrosis.
- Ancillary: Diffuse expression of p63 and Ki-67 proliferation index > 10%.
Reference Gallery:
Epithelioid trophoblastic tumour. There is a destructive nodular mass lesion.
Epithelioid trophoblastic tumour. There is a proliferation of relatively uniform cells with geographical tumour cell necrosis.
Epithelioid trophoblastic tumour. There is often calcification.
Epithelioid trophoblastic tumour. Tumour cells colonizing cervical mucosal epithelium may simulate a high-grade squamous intraepithelial lesion.
Epithelioid trophoblastic tumour. Eosinophilic hyaline-like material within tumour cell nests may simulate keratinizing squamous cell carcinoma.
Epithelioid trophoblastic tumour. Presence of decidualized benign stromal cells around tumour nests.
Epithelioid trophoblastic tumour. Diffuse expression of p63 in tumour cells.
Epithelioid trophoblastic tumour. Ki-67 proliferation index of > 10%.
Epithelioid trophoblastic tumour. A 49-year-old woman (gravida 4 para 4) presented with vaginal bleeding and a large mass measuring 12.2 × 8.7 × 8.5 cm, involving the uterus and cervix. Serum β-hCG at presentation was 24,310 IU/L. She received 7 cycles of chemotherapy, and within 6 months there was a dramatic reduction in the size (3.7 cm) of the lesion, and serum β-hCG dropped to 6 IU/L. Hysterectomy with bilateral salpingo-oophorectomy was performed. A homogenous tan-grey tumour measuring 35 mm in maximum dimension is present in the anterior lower uterine segment, extending to the cervix with a peripheral rim of yellowish-brown necrosis. Histologically, the tumour cells invade beyond the macroscopic confines of the visible tumour mass and extend to < 1 mm from the parametrial/paracervical margin.

Q: Presenting classically with a watery vaginal discharge, [...] features infiltrative mucinous glands composed of cells with distinct cell borders, abundant clear to pale eosinophilic cytoplasm, and a lack of HPV association.
Gastric-type endocervical adenocarcinoma. Irregularly shaped, infiltrative mucinous glands and tumour clusters with evident nuclear atypia.
Gastric-type endocervical adenocarcinoma. Tumoural glands are composed of mucinous cells with ample granular to foamy cytoplasm and distinct cell borders.
A: Adenocarcinoma, HPV-independent, gastric type, of the uterine cervix
Back Extra: Adenocarcinoma, HPV-independent, gastric type, of the uterine cervix
- Clinical: Adenocarcinoma, HPV-independent, gastric type, of the uterine cervix is characterized by bleeding and watery vaginal discharge, commonly affecting women aged 50-55 years.
- Micro: The hallmark feature is glandular cells with abundant clear or pale eosinophilic cytoplasm, distinct cell borders, and neutral mucins.
- Ancillary: Immunohistochemical markers such as HIK1083, MUC6, PAX8, CAIX, CEA, and CK7 are frequently positive, while HPV testing is negative.
Reference Gallery:
Gastric-type endocervical adenocarcinoma. Irregularly shaped, infiltrative mucinous glands and tumour clusters with evident nuclear atypia.
Gastric-type endocervical adenocarcinoma. Tumoural glands are composed of mucinous cells with ample granular to foamy cytoplasm and distinct cell borders.
Gastric-type endocervical adenocarcinoma. Poorly differentiated areas display frank infiltration and severe atypia. Notice the relatively abundant eosinophilic to vacuolated cytoplasm.
Gastric-type endocervical adenocarcinoma, minimal deviation type. Proliferation of very well-differentiated glands with smooth contours, haphazardly distributed.
Gastric-type endocervical adenocarcinoma, minimal deviation type. Glands are composed of tall columnar epithelium with abundant pale and foamy cytoplasm and distinct cell borders (compare with normal endocervical gland, top centre). Nuclear atypia (left aspect) can be encountered, but is usually a focal finding.

Q: Adenocarcinoma, HPV-independent, gastric type, of the uterine cervix encompasses an exceptionally well-differentiated variant known as the [...] type, which is morphologically characterized by a proliferation of haphazardly distributed glands with deceptively smooth contours.
Gastric-type endocervical adenocarcinoma, minimal deviation type. Proliferation of very well-differentiated glands with smooth contours, haphazardly distributed.
Gastric-type endocervical adenocarcinoma, minimal deviation type. Glands are composed of tall columnar epithelium with abundant pale and foamy cytoplasm and distinct cell borders (compare with normal endocervical gland, top centre). Nuclear atypia (left aspect) can be encountered, but is usually a focal finding.
A: minimal deviation
Back Extra: Adenocarcinoma, HPV-independent, gastric type, of the uterine cervix
- Clinical: Adenocarcinoma, HPV-independent, gastric type, of the uterine cervix is characterized by bleeding and watery vaginal discharge, commonly affecting women aged 50-55 years.
- Micro: The hallmark feature is glandular cells with abundant clear or pale eosinophilic cytoplasm, distinct cell borders, and neutral mucins.
- Ancillary: Immunohistochemical markers such as HIK1083, MUC6, PAX8, CAIX, CEA, and CK7 are frequently positive, while HPV testing is negative.
Reference Gallery:
Gastric-type endocervical adenocarcinoma. Irregularly shaped, infiltrative mucinous glands and tumour clusters with evident nuclear atypia.
Gastric-type endocervical adenocarcinoma. Tumoural glands are composed of mucinous cells with ample granular to foamy cytoplasm and distinct cell borders.
Gastric-type endocervical adenocarcinoma. Poorly differentiated areas display frank infiltration and severe atypia. Notice the relatively abundant eosinophilic to vacuolated cytoplasm.
Gastric-type endocervical adenocarcinoma, minimal deviation type. Proliferation of very well-differentiated glands with smooth contours, haphazardly distributed.
Gastric-type endocervical adenocarcinoma, minimal deviation type. Glands are composed of tall columnar epithelium with abundant pale and foamy cytoplasm and distinct cell borders (compare with normal endocervical gland, top centre). Nuclear atypia (left aspect) can be encountered, but is usually a focal finding.

Q: Microscopically, Adenocarcinoma, HPV-associated, of the uterine cervix is typically characterized by irregular and confluent glands with elongated, hyperchromatic nuclei, and conspicuous [...].
HPV-associated endocervical adenocarcinoma, usual type. Irregular and confluent glands composed of mucin-depleted cells, which show indistinct cytoplasm and elongated, pseudostratified, hyperchromatic nuclei. Conspicuous apical mitoses and apoptoses are present.
HPV-associated endocervical adenocarcinoma, mucinous NOS (endocervical) type. Irregular glands lined by columnar mucinous epithelium displaying evident nuclear hyperchromasia, mitoses, and apoptoses.
A: apical mitoses and apoptoses
Back Extra: Adenocarcinoma, HPV-associated, of the uterine cervix
- Clinical: Adenocarcinoma, HPV-associated, of the uterine cervix presents with abnormal uterine bleeding and/or a mass, and is often detected through cytology screening. The mean patient age at presentation is 40–42 years.
- Micro: HPV-associated endocervical adenocarcinoma is characterized by irregular and confluent glands with elongated, hyperchromatic nuclei, and conspicuous apical mitoses and apoptoses.
- Ancillary: p16 immunohistochemistry is an effective (yet flawed) indirect test for HR-HPV infection, showing diffuse block-type or every-cell staining in approximately 95% of cases.
Reference Gallery:
HPV-associated endocervical adenocarcinoma, usual type. Irregular and confluent glands composed of mucin-depleted cells, which show indistinct cytoplasm and elongated, pseudostratified, hyperchromatic nuclei. Conspicuous apical mitoses and apoptoses are present.
HPV-associated endocervical adenocarcinoma, mucinous NOS (endocervical) type. Irregular glands lined by columnar mucinous epithelium displaying evident nuclear hyperchromasia, mitoses, and apoptoses.
HPV-associated endocervical adenocervical adenocarcinoma, mucinous NOS (endocervical) type. Cribriform proliferation composed of columnar mucinous epithelium displaying evident nuclear hyperchromasia.
HPV-associated endocervical adenocarcinoma, invasive stratified mucin-producing type. Invasive proliferation of solid nests in an inflamed stroma. Tumour nests are composed of mucinous epithelial cells forming aggregates.
HPV-associated endocervical adenocarcinoma, invasive stratified mucin-producing type. Tumour cells arranged in nests and aggregates. Notice the mucinous cytoplasm throughout the lesion.
HPV-associated endocervical adenocarcinoma, villoglandular type. Tumour with predominant exophytic papillary growth. Papillae are lined by mucin-depleted (usual-type) epithelium with nuclear hyperchromasia.
HPV-associated endocervical adenocarcinoma. Pattern A. Well-differentiated proliferation composed of well-formed glands, some vaguely lobulated. Note the absence of infiltrative glands, confluence, non–gland-forming tumour, stromal desmoplasia, and lymphatic vascular invasion.
HPV-associated endocervical adenocarcinoma. Pattern B HPV-associated invasive endocervical adenocarcinoma. Infiltrative (angulated, incomplete) glands eliciting inflammation and stromal desmoplasia, originating from well-demarcated (pattern A) glands.
Pattern C HPV-associated invasive endocervical adenocarcinoma. Invasive tumour composed of irregular, angulated, and elongated (rather than round and smooth-contoured) glands.
Pattern C HPV-associated invasive endocervical adenocarcinoma. Irregular glands and tumour cell clusters eliciting a significant stromal desmoplastic reaction.
HPV-associated endocervical adenocarcinoma. Pattern A. The lesion, although clearly invasive given its marked glandular density, retains a clustered and vaguely lobulated architecture and lacks destructive infiltration.
HPV-associated endocervical adenocarcinoma. Pattern B. Irregular nests and glands arising from well-formed glands, in a background of dense inflammation.

Q: Presenting typically at a mean age of 40–42 years with abnormal uterine bleeding or a mass, a malignancy characterized microscopically by irregular, confluent glands with hyperchromatic nuclei is most likely [...].
HPV-associated endocervical adenocarcinoma, usual type. Irregular and confluent glands composed of mucin-depleted cells, which show indistinct cytoplasm and elongated, pseudostratified, hyperchromatic nuclei. Conspicuous apical mitoses and apoptoses are present.
Pattern C HPV-associated invasive endocervical adenocarcinoma. Invasive tumour composed of irregular, angulated, and elongated (rather than round and smooth-contoured) glands.
A: Adenocarcinoma, HPV-associated, of the uterine cervix
Back Extra: Adenocarcinoma, HPV-associated, of the uterine cervix
- Clinical: Adenocarcinoma, HPV-associated, of the uterine cervix presents with abnormal uterine bleeding and/or a mass, and is often detected through cytology screening. The mean patient age at presentation is 40–42 years.
- Micro: HPV-associated endocervical adenocarcinoma is characterized by irregular and confluent glands with elongated, hyperchromatic nuclei, and conspicuous apical mitoses and apoptoses.
- Ancillary: p16 immunohistochemistry is an effective (yet flawed) indirect test for HR-HPV infection, showing diffuse block-type or every-cell staining in approximately 95% of cases.
Reference Gallery:
HPV-associated endocervical adenocarcinoma, usual type. Irregular and confluent glands composed of mucin-depleted cells, which show indistinct cytoplasm and elongated, pseudostratified, hyperchromatic nuclei. Conspicuous apical mitoses and apoptoses are present.
HPV-associated endocervical adenocarcinoma, mucinous NOS (endocervical) type. Irregular glands lined by columnar mucinous epithelium displaying evident nuclear hyperchromasia, mitoses, and apoptoses.
HPV-associated endocervical adenocervical adenocarcinoma, mucinous NOS (endocervical) type. Cribriform proliferation composed of columnar mucinous epithelium displaying evident nuclear hyperchromasia.
HPV-associated endocervical adenocarcinoma, invasive stratified mucin-producing type. Invasive proliferation of solid nests in an inflamed stroma. Tumour nests are composed of mucinous epithelial cells forming aggregates.
HPV-associated endocervical adenocarcinoma, invasive stratified mucin-producing type. Tumour cells arranged in nests and aggregates. Notice the mucinous cytoplasm throughout the lesion.
HPV-associated endocervical adenocarcinoma, villoglandular type. Tumour with predominant exophytic papillary growth. Papillae are lined by mucin-depleted (usual-type) epithelium with nuclear hyperchromasia.
HPV-associated endocervical adenocarcinoma. Pattern A. Well-differentiated proliferation composed of well-formed glands, some vaguely lobulated. Note the absence of infiltrative glands, confluence, non–gland-forming tumour, stromal desmoplasia, and lymphatic vascular invasion.
HPV-associated endocervical adenocarcinoma. Pattern B HPV-associated invasive endocervical adenocarcinoma. Infiltrative (angulated, incomplete) glands eliciting inflammation and stromal desmoplasia, originating from well-demarcated (pattern A) glands.
Pattern C HPV-associated invasive endocervical adenocarcinoma. Invasive tumour composed of irregular, angulated, and elongated (rather than round and smooth-contoured) glands.
Pattern C HPV-associated invasive endocervical adenocarcinoma. Irregular glands and tumour cell clusters eliciting a significant stromal desmoplastic reaction.
HPV-associated endocervical adenocarcinoma. Pattern A. The lesion, although clearly invasive given its marked glandular density, retains a clustered and vaguely lobulated architecture and lacks destructive infiltration.
HPV-associated endocervical adenocarcinoma. Pattern B. Irregular nests and glands arising from well-formed glands, in a background of dense inflammation.

Q: Nodular-stage Kaposi Sarcoma is characterized by a prominent dermal proliferation of plump, uniform spindle cells forming characteristic [...] containing erythrocytes.
Kaposi sarcoma. Nodular-stage Kaposi sarcoma. There is prominent expansion of the dermis by a cellular proliferation of spindle cells, with small areas of haemorrhage. Ectatic vessels and small slit-like spaces containing erythrocytes are also discernible.
Kaposi sarcoma. Nodular-stage Kaposi sarcoma. The cells are plump but uniform, with elongated ovoid to spindled vesicular nuclei. Small vascular spaces are interspersed, along with haemosiderin-laden macrophages.
A: slit-like spaces
Back Extra: Kaposi Sarcoma
- Clinical: Vulvar Kaposi sarcoma often manifests as bluish-red single or multiple masses or exophytic indurated nodules, and can be asymptomatic or associated with pain or pruritus.
- Micro: Nodular-stage Kaposi sarcoma is characterized by prominent expansion of the dermis with cellular proliferation of spindle cells, small areas of haemorrhage, and ectatic vessels.
- Ancillary: HHV8 immunohistochemistry is almost invariably positive in Kaposi sarcoma and is crucial for diagnosis.
Reference Gallery:
Kaposi sarcoma. Nodular-stage Kaposi sarcoma. There is prominent expansion of the dermis by a cellular proliferation of spindle cells, with small areas of haemorrhage. Ectatic vessels and small slit-like spaces containing erythrocytes are also discernible.
Kaposi sarcoma. Nodular-stage Kaposi sarcoma. The cells are plump but uniform, with elongated ovoid to spindled vesicular nuclei. Small vascular spaces are interspersed, along with haemosiderin-laden macrophages.
Kaposi sarcoma. Occasional hyaline globules are noted; these can be intracellular or extracellular.
Kaposi sarcoma. Tumour cell nuclei show strong expression of HHV8 in spindle cells.

Q: In addition to hemosiderin-laden macrophages and small areas of hemorrhage, microscopic examination of Kaposi Sarcoma often reveals the presence of intra- or extracellular [...].
Kaposi sarcoma. Occasional hyaline globules are noted; these can be intracellular or extracellular.
A: hyaline globules
Back Extra: Kaposi Sarcoma
- Clinical: Vulvar Kaposi sarcoma often manifests as bluish-red single or multiple masses or exophytic indurated nodules, and can be asymptomatic or associated with pain or pruritus.
- Micro: Nodular-stage Kaposi sarcoma is characterized by prominent expansion of the dermis with cellular proliferation of spindle cells, small areas of haemorrhage, and ectatic vessels.
- Ancillary: HHV8 immunohistochemistry is almost invariably positive in Kaposi sarcoma and is crucial for diagnosis.
Reference Gallery:
Kaposi sarcoma. Nodular-stage Kaposi sarcoma. There is prominent expansion of the dermis by a cellular proliferation of spindle cells, with small areas of haemorrhage. Ectatic vessels and small slit-like spaces containing erythrocytes are also discernible.
Kaposi sarcoma. Nodular-stage Kaposi sarcoma. The cells are plump but uniform, with elongated ovoid to spindled vesicular nuclei. Small vascular spaces are interspersed, along with haemosiderin-laden macrophages.
Kaposi sarcoma. Occasional hyaline globules are noted; these can be intracellular or extracellular.
Kaposi sarcoma. Tumour cell nuclei show strong expression of HHV8 in spindle cells.

Q: Immunohistochemistry is crucial for confirming the diagnosis of Kaposi Sarcoma, as the neoplastic spindle cells invariably show strong nuclear expression for [...].
Kaposi sarcoma. Tumour cell nuclei show strong expression of HHV8 in spindle cells.
A: HHV8
Back Extra: Kaposi Sarcoma
- Clinical: Vulvar Kaposi sarcoma often manifests as bluish-red single or multiple masses or exophytic indurated nodules, and can be asymptomatic or associated with pain or pruritus.
- Micro: Nodular-stage Kaposi sarcoma is characterized by prominent expansion of the dermis with cellular proliferation of spindle cells, small areas of haemorrhage, and ectatic vessels.
- Ancillary: HHV8 immunohistochemistry is almost invariably positive in Kaposi sarcoma and is crucial for diagnosis.
Reference Gallery:
Kaposi sarcoma. Nodular-stage Kaposi sarcoma. There is prominent expansion of the dermis by a cellular proliferation of spindle cells, with small areas of haemorrhage. Ectatic vessels and small slit-like spaces containing erythrocytes are also discernible.
Kaposi sarcoma. Nodular-stage Kaposi sarcoma. The cells are plump but uniform, with elongated ovoid to spindled vesicular nuclei. Small vascular spaces are interspersed, along with haemosiderin-laden macrophages.
Kaposi sarcoma. Occasional hyaline globules are noted; these can be intracellular or extracellular.
Kaposi sarcoma. Tumour cell nuclei show strong expression of HHV8 in spindle cells.

Q: In Adenocarcinoma, HPV-independent, mesonephric type, of the uterine cervix, the classic microscopic pattern features back-to-back tubules lined by cuboidal cells that characteristically contain [...].
Mesonephric carcinoma. Classic tubular and ductal patterns. The tubules are lined by cuboidal cells and contain dense eosinophilic secretions, as well as focal intraluminal necrotic debris. The ductal pattern comprises angulated glands that are lined with columnar cells.
A: dense eosinophilic secretions
Back Extra: Adenocarcinoma, HPV-independent, mesonephric type, of the uterine cervix
- Clinical: Adenocarcinoma, HPV-independent, mesonephric type, of the uterine cervix typically presents in patients around the age of 53 years with symptoms such as abnormal vaginal bleeding, abdominal pain, and uterine prolapse.
- Micro: The classic microscopic pattern includes back-to-back tubules lined by cuboidal cells with dense eosinophilic secretions and angulated glands lined by columnar cells.
- Ancillary: Tumors are positive for GATA3, PAX8, and CD10 (luminal staining pattern) but negative for ER, napsin A, and AMACR. They often harbor KRAS mutations and gain in chromosome 1q.
Reference Gallery:
Mesonephric carcinoma. Classic tubular and ductal patterns. The tubules are lined by cuboidal cells and contain dense eosinophilic secretions, as well as focal intraluminal necrotic debris. The ductal pattern comprises angulated glands that are lined with columnar cells.

Q: The microscopic ductal pattern of Adenocarcinoma, HPV-independent, mesonephric type, of the uterine cervix typically comprises [...] glands lined by columnar cells, which are often seen alongside tubular formations.
Mesonephric carcinoma. Classic tubular and ductal patterns. The tubules are lined by cuboidal cells and contain dense eosinophilic secretions, as well as focal intraluminal necrotic debris. The ductal pattern comprises angulated glands that are lined with columnar cells.
A: angulated
Back Extra: Adenocarcinoma, HPV-independent, mesonephric type, of the uterine cervix
- Clinical: Adenocarcinoma, HPV-independent, mesonephric type, of the uterine cervix typically presents in patients around the age of 53 years with symptoms such as abnormal vaginal bleeding, abdominal pain, and uterine prolapse.
- Micro: The classic microscopic pattern includes back-to-back tubules lined by cuboidal cells with dense eosinophilic secretions and angulated glands lined by columnar cells.
- Ancillary: Tumors are positive for GATA3, PAX8, and CD10 (luminal staining pattern) but negative for ER, napsin A, and AMACR. They often harbor KRAS mutations and gain in chromosome 1q.
Reference Gallery:
Mesonephric carcinoma. Classic tubular and ductal patterns. The tubules are lined by cuboidal cells and contain dense eosinophilic secretions, as well as focal intraluminal necrotic debris. The ductal pattern comprises angulated glands that are lined with columnar cells.

Q: Carcinoma admixed with neuroendocrine carcinoma is most frequently found in the [...], often presenting similarly to pure neuroendocrine carcinomas.
Cervical mixed small cell neuroendocrine carcinoma (SCNEC) and adenocarcinoma. Low-power view of cervical mixed SCNEC (left) and adenocarcinoma (right).
A: uterine cervix
Back Extra: Carcinoma admixed with neuroendocrine carcinoma
- Clinical: Carcinoma admixed with neuroendocrine carcinoma is most frequently found in the uterine cervix and has a similar clinical presentation to pure neuroendocrine carcinomas.
- Micro: In the cervix, the non-neuroendocrine component is usually an adenocarcinoma of the usual HPV-associated type, while the neuroendocrine component is typically small cell or large cell carcinoma.
- Ancillary: Immunohistochemistry is crucial for identifying the components, with the neuroendocrine component being positive for synaptophysin and the non-neuroendocrine component being negative.
Reference Gallery:
Cervical mixed small cell neuroendocrine carcinoma (SCNEC) and adenocarcinoma. Cervical mixed SCNEC (left) and adenocarcinoma (right).
Cervical mixed small cell neuroendocrine carcinoma (SCNEC) and adenocarcinoma. Low-power view of cervical mixed SCNEC (left) and adenocarcinoma (right).
Cervical mixed small cell neuroendocrine carcinoma (SCNEC) and adenocarcinoma. The neuroendocrine carcinoma (left) is immunoreactive with synaptophysin while the adenocarcinoma component (right) is negative.

Q: In the uterine cervix, the non-neuroendocrine component of Carcinoma admixed with neuroendocrine carcinoma is most commonly an HPV-associated [...].
Cervical mixed small cell neuroendocrine carcinoma (SCNEC) and adenocarcinoma. Cervical mixed SCNEC (left) and adenocarcinoma (right).
Cervical mixed small cell neuroendocrine carcinoma (SCNEC) and adenocarcinoma. Low-power view of cervical mixed SCNEC (left) and adenocarcinoma (right).
A: adenocarcinoma
Back Extra: Carcinoma admixed with neuroendocrine carcinoma
- Clinical: Carcinoma admixed with neuroendocrine carcinoma is most frequently found in the uterine cervix and has a similar clinical presentation to pure neuroendocrine carcinomas.
- Micro: In the cervix, the non-neuroendocrine component is usually an adenocarcinoma of the usual HPV-associated type, while the neuroendocrine component is typically small cell or large cell carcinoma.
- Ancillary: Immunohistochemistry is crucial for identifying the components, with the neuroendocrine component being positive for synaptophysin and the non-neuroendocrine component being negative.
Reference Gallery:
Cervical mixed small cell neuroendocrine carcinoma (SCNEC) and adenocarcinoma. Cervical mixed SCNEC (left) and adenocarcinoma (right).
Cervical mixed small cell neuroendocrine carcinoma (SCNEC) and adenocarcinoma. Low-power view of cervical mixed SCNEC (left) and adenocarcinoma (right).
Cervical mixed small cell neuroendocrine carcinoma (SCNEC) and adenocarcinoma. The neuroendocrine carcinoma (left) is immunoreactive with synaptophysin while the adenocarcinoma component (right) is negative.

Q: To confirm the distinct components in Carcinoma admixed with neuroendocrine carcinoma, the neuroendocrine component will characteristically show immunoreactivity for [...], while the non-neuroendocrine component remains negative.
Cervical mixed small cell neuroendocrine carcinoma (SCNEC) and adenocarcinoma. The neuroendocrine carcinoma (left) is immunoreactive with synaptophysin while the adenocarcinoma component (right) is negative.
A: synaptophysin
Back Extra: Carcinoma admixed with neuroendocrine carcinoma
- Clinical: Carcinoma admixed with neuroendocrine carcinoma is most frequently found in the uterine cervix and has a similar clinical presentation to pure neuroendocrine carcinomas.
- Micro: In the cervix, the non-neuroendocrine component is usually an adenocarcinoma of the usual HPV-associated type, while the neuroendocrine component is typically small cell or large cell carcinoma.
- Ancillary: Immunohistochemistry is crucial for identifying the components, with the neuroendocrine component being positive for synaptophysin and the non-neuroendocrine component being negative.
Reference Gallery:
Cervical mixed small cell neuroendocrine carcinoma (SCNEC) and adenocarcinoma. Cervical mixed SCNEC (left) and adenocarcinoma (right).
Cervical mixed small cell neuroendocrine carcinoma (SCNEC) and adenocarcinoma. Low-power view of cervical mixed SCNEC (left) and adenocarcinoma (right).
Cervical mixed small cell neuroendocrine carcinoma (SCNEC) and adenocarcinoma. The neuroendocrine carcinoma (left) is immunoreactive with synaptophysin while the adenocarcinoma component (right) is negative.

Q: Histologically, Large Cell Neuroendocrine Carcinoma (LCNEC) typically exhibits a diffuse growth pattern composed of large cells with prominent nucleoli, abundant cytoplasm, and frequent areas of [...].
Large cell neuroendocrine carcinoma (LCNEC). This cervical tumour is composed of cells with prominent nucleoli, abundant cytoplasm, and areas of necrosis.
Large cell neuroendocrine carcinoma (LCNEC). This tumour exhibits a diffuse growth pattern of cells with abundant eosinophilic cytoplasm and prominent nucleoli.
A: necrosis
Back Extra: Large Cell Neuroendocrine Carcinoma (LCNEC)
- Clinical: Cervical and endometrial LCNEC typically present with abnormal vaginal bleeding, while ovarian LCNEC presents with symptoms related to an adnexal mass.
- Micro: LCNEC is characterized by large cells with prominent nucleoli, abundant cytoplasm, and areas of necrosis, often with a diffuse growth pattern.
- Ancillary: Expression of at least one neuroendocrine marker (chromogranin, synaptophysin, or CD56) and diffuse block-type p16 immunoreactivity are diagnostic.
Reference Gallery:
Large cell neuroendocrine carcinoma (LCNEC). This cervical tumour is composed of cells with prominent nucleoli, abundant cytoplasm, and areas of necrosis.
Large cell neuroendocrine carcinoma (LCNEC). This cervical tumour exhibits diffuse immunoreactivity with synaptophysin.
Large cell neuroendocrine carcinoma (LCNEC). This tumour exhibits a diffuse growth pattern of cells with abundant eosinophilic cytoplasm and prominent nucleoli.

Q: To confirm the diagnosis of Large Cell Neuroendocrine Carcinoma (LCNEC), the tumor must demonstrate diffuse block-type p16 immunoreactivity along with the expression of at least one neuroendocrine marker, such as chromogranin, CD56, or [...].
Large cell neuroendocrine carcinoma (LCNEC). This cervical tumour exhibits diffuse immunoreactivity with synaptophysin.
A: synaptophysin
Back Extra: Large Cell Neuroendocrine Carcinoma (LCNEC)
- Clinical: Cervical and endometrial LCNEC typically present with abnormal vaginal bleeding, while ovarian LCNEC presents with symptoms related to an adnexal mass.
- Micro: LCNEC is characterized by large cells with prominent nucleoli, abundant cytoplasm, and areas of necrosis, often with a diffuse growth pattern.
- Ancillary: Expression of at least one neuroendocrine marker (chromogranin, synaptophysin, or CD56) and diffuse block-type p16 immunoreactivity are diagnostic.
Reference Gallery:
Large cell neuroendocrine carcinoma (LCNEC). This cervical tumour is composed of cells with prominent nucleoli, abundant cytoplasm, and areas of necrosis.
Large cell neuroendocrine carcinoma (LCNEC). This cervical tumour exhibits diffuse immunoreactivity with synaptophysin.
Large cell neuroendocrine carcinoma (LCNEC). This tumour exhibits a diffuse growth pattern of cells with abundant eosinophilic cytoplasm and prominent nucleoli.

Q: A cervical neoplasm demonstrating a nested pattern, focal glandular formation, and relatively uniform nuclei that is positive for synaptophysin and chromogranin is characteristic of a grade 1 [...].
Neuroendocrine tumour (NET) of cervix, grade 1. Nested pattern, focal glandular formation, and cells with a moderate amount of cytoplasm and relatively uniform nuclei.
A: neuroendocrine tumor
Back Extra: Neuroendocrine Tumour
- Clinical: Patients with cervical Neuroendocrine Tumours may present with abnormal cervical smear, vaginal bleeding, and a visible cervical lesion.
- Micro: Grade 1 Neuroendocrine Tumours show a nested and glandular pattern with uniform nuclei, while grade 2 tumours exhibit nested and trabecular patterns with variable nuclei and mitotic figures.
- Ancillary: Immunohistochemical markers (synaptophysin, chromogranin, CD56) are crucial for confirming neuroendocrine differentiation in Neuroendocrine Tumours.
Reference Gallery:
Neuroendocrine tumour (NET) of cervix, grade 1. Nested pattern, focal glandular formation, and cells with a moderate amount of cytoplasm and relatively uniform nuclei.
Neuroendocrine tumour (NET) of cervix, grade 2. Nested and trabecular patterns, cells with a moderate amount of cytoplasm, variable nuclei, and mitotic figures.

Q: A grade 2 neuroendocrine tumor of the cervix is distinguished by the presence of a nested and [...] architectural pattern, variable nuclei, and prominent mitotic figures.
Neuroendocrine tumour (NET) of cervix, grade 2. Nested and trabecular patterns, cells with a moderate amount of cytoplasm, variable nuclei, and mitotic figures.
A: trabecular
Back Extra: Neuroendocrine Tumour
- Clinical: Patients with cervical Neuroendocrine Tumours may present with abnormal cervical smear, vaginal bleeding, and a visible cervical lesion.
- Micro: Grade 1 Neuroendocrine Tumours show a nested and glandular pattern with uniform nuclei, while grade 2 tumours exhibit nested and trabecular patterns with variable nuclei and mitotic figures.
- Ancillary: Immunohistochemical markers (synaptophysin, chromogranin, CD56) are crucial for confirming neuroendocrine differentiation in Neuroendocrine Tumours.
Reference Gallery:
Neuroendocrine tumour (NET) of cervix, grade 1. Nested pattern, focal glandular formation, and cells with a moderate amount of cytoplasm and relatively uniform nuclei.
Neuroendocrine tumour (NET) of cervix, grade 2. Nested and trabecular patterns, cells with a moderate amount of cytoplasm, variable nuclei, and mitotic figures.

Q: Histologically, Small Cell Neuroendocrine Carcinoma is characterized by sheets of cells with scant cytoplasm, hyperchromatic nuclei, abundant mitotic activity, and characteristic [...].
Small cell neuroendocrine carcinoma (SCNEC). This cervical lesion is composed of cells with hyperchromatic nuclei, scant cytoplasm, and abundant mitotic activity. There is nuclear moulding in areas.
Small cell neuroendocrine carcinoma (SCNEC). Low-power view exhibiting a diffuse population of cells with scant cytoplasm.
A: nuclear molding
Back Extra: Small Cell Neuroendocrine Carcinoma
- Clinical: Small cell neuroendocrine carcinoma (SCNEC) of the cervix typically presents with abnormal vaginal bleeding and is diagnosed at a mean age of 48.1 years.
- Micro: SCNEC is characterized by sheets of highly atypical cells with scant cytoplasm, hyperchromatic nuclei, nuclear moulding, and abundant mitotic activity.
- Ancillary: Immunohistochemical markers such as synaptophysin and chromogranin are crucial for diagnosing SCNEC, with synaptophysin being the most consistently expressed marker.
Reference Gallery:
Small cell neuroendocrine carcinoma (SCNEC). This cervical lesion is composed of cells with hyperchromatic nuclei, scant cytoplasm, and abundant mitotic activity. There is nuclear moulding in areas.
Small cell neuroendocrine carcinoma (SCNEC). Low-power view exhibiting a diffuse population of cells with scant cytoplasm.
Small cell neuroendocrine carcinoma (SCNEC). This lesion exhibits diffuse block-type immunoreactivity with p16.
Small cell neuroendocrine carcinoma (SCNEC). There is diffuse positive staining with synaptophysin.

Q: In Small Cell Neuroendocrine Carcinoma, the most consistently expressed immunohistochemical neuroendocrine marker is [...].
Small cell neuroendocrine carcinoma (SCNEC). There is diffuse positive staining with synaptophysin.
A: synaptophysin
Back Extra: Small Cell Neuroendocrine Carcinoma
- Clinical: Small cell neuroendocrine carcinoma (SCNEC) of the cervix typically presents with abnormal vaginal bleeding and is diagnosed at a mean age of 48.1 years.
- Micro: SCNEC is characterized by sheets of highly atypical cells with scant cytoplasm, hyperchromatic nuclei, nuclear moulding, and abundant mitotic activity.
- Ancillary: Immunohistochemical markers such as synaptophysin and chromogranin are crucial for diagnosing SCNEC, with synaptophysin being the most consistently expressed marker.
Reference Gallery:
Small cell neuroendocrine carcinoma (SCNEC). This cervical lesion is composed of cells with hyperchromatic nuclei, scant cytoplasm, and abundant mitotic activity. There is nuclear moulding in areas.
Small cell neuroendocrine carcinoma (SCNEC). Low-power view exhibiting a diffuse population of cells with scant cytoplasm.
Small cell neuroendocrine carcinoma (SCNEC). This lesion exhibits diffuse block-type immunoreactivity with p16.
Small cell neuroendocrine carcinoma (SCNEC). There is diffuse positive staining with synaptophysin.

Q: Cervical Small Cell Neuroendocrine Carcinoma typically exhibits diffuse, block-type immunoreactivity for [...].
Small cell neuroendocrine carcinoma (SCNEC). This lesion exhibits diffuse block-type immunoreactivity with p16.
A: p16
Back Extra: Small Cell Neuroendocrine Carcinoma
- Clinical: Small cell neuroendocrine carcinoma (SCNEC) of the cervix typically presents with abnormal vaginal bleeding and is diagnosed at a mean age of 48.1 years.
- Micro: SCNEC is characterized by sheets of highly atypical cells with scant cytoplasm, hyperchromatic nuclei, nuclear moulding, and abundant mitotic activity.
- Ancillary: Immunohistochemical markers such as synaptophysin and chromogranin are crucial for diagnosing SCNEC, with synaptophysin being the most consistently expressed marker.
Reference Gallery:
Small cell neuroendocrine carcinoma (SCNEC). This cervical lesion is composed of cells with hyperchromatic nuclei, scant cytoplasm, and abundant mitotic activity. There is nuclear moulding in areas.
Small cell neuroendocrine carcinoma (SCNEC). Low-power view exhibiting a diffuse population of cells with scant cytoplasm.
Small cell neuroendocrine carcinoma (SCNEC). This lesion exhibits diffuse block-type immunoreactivity with p16.
Small cell neuroendocrine carcinoma (SCNEC). There is diffuse positive staining with synaptophysin.

Q: In Squamous Cell Carcinoma, HPV-associated, of the uterine cervix, ancillary immunohistochemical testing almost always demonstrates strong and diffuse overexpression of [...].
Non-keratinizing squamous cell carcinoma. Strong and diffuse p16 overexpression is present in almost all HPV-associated squamous cell carcinomas.
A: p16
Back Extra: Squamous Cell Carcinoma, HPV-associated, of the uterine cervix
- Clinical: The average age at diagnosis in women from high-income countries is in the sixth decade of life (median age: 51 years).
- Micro: Non-keratinizing squamous cell carcinomas are characterized by infiltrative nests of squamous cells without keratinization, while keratinizing variants show presence of keratin pearls.
- Ancillary: Strong and diffuse p16 overexpression is a key finding in almost all HPV-associated squamous cell carcinomas of the uterine cervix.
Reference Gallery:
Non-keratinizing squamous cell carcinoma. This is characterized by infiltrative nests of squamous cells without keratinization.
Non-keratinizing squamous cell carcinoma. Strong and diffuse p16 overexpression is present in almost all HPV-associated squamous cell carcinomas.
Keratinizing squamous cell carcinoma. Keratinizing squamous cell carcinoma shows formation of keratin pearls or marked individual cell keratinization.
Papillary squamous cell carcinoma. The tumour is characterized by the presence of fibrovascular cores lined by multilayered atypical epithelium.
Non-keratinizing squamous cell carcinoma. Cytology: large syncytial aggregates of tumour cells with karrhyorectic debris along the edges (SurePath).
Keratinizing squamous cell carcinoma. Heavily keratinized cells with N:C ratios ranging from low to high, with hyperchromatic nuclei (ThinPrep).
Keratinizing squamous cell carcinoma. Severely atypical keratinized squamous cells with necrotic background.

Q: The keratinizing variant of Squamous Cell Carcinoma, HPV-associated, of the uterine cervix is histologically distinguished from the non-keratinizing variant by the presence of prominent [...].
Non-keratinizing squamous cell carcinoma. This is characterized by infiltrative nests of squamous cells without keratinization.
Keratinizing squamous cell carcinoma. Keratinizing squamous cell carcinoma shows formation of keratin pearls or marked individual cell keratinization.
A: keratin pearls
Back Extra: Squamous Cell Carcinoma, HPV-associated, of the uterine cervix
- Clinical: The average age at diagnosis in women from high-income countries is in the sixth decade of life (median age: 51 years).
- Micro: Non-keratinizing squamous cell carcinomas are characterized by infiltrative nests of squamous cells without keratinization, while keratinizing variants show presence of keratin pearls.
- Ancillary: Strong and diffuse p16 overexpression is a key finding in almost all HPV-associated squamous cell carcinomas of the uterine cervix.
Reference Gallery:
Non-keratinizing squamous cell carcinoma. This is characterized by infiltrative nests of squamous cells without keratinization.
Non-keratinizing squamous cell carcinoma. Strong and diffuse p16 overexpression is present in almost all HPV-associated squamous cell carcinomas.
Keratinizing squamous cell carcinoma. Keratinizing squamous cell carcinoma shows formation of keratin pearls or marked individual cell keratinization.
Papillary squamous cell carcinoma. The tumour is characterized by the presence of fibrovascular cores lined by multilayered atypical epithelium.
Non-keratinizing squamous cell carcinoma. Cytology: large syncytial aggregates of tumour cells with karrhyorectic debris along the edges (SurePath).
Keratinizing squamous cell carcinoma. Heavily keratinized cells with N:C ratios ranging from low to high, with hyperchromatic nuclei (ThinPrep).
Keratinizing squamous cell carcinoma. Severely atypical keratinized squamous cells with necrotic background.

Q: Cytologic preparations showing heavily keratinized atypical cells with hyperchromatic nuclei on a necrotic background are characteristic of the keratinizing variant of [...].
Keratinizing squamous cell carcinoma. Heavily keratinized cells with N:C ratios ranging from low to high, with hyperchromatic nuclei (ThinPrep).
Keratinizing squamous cell carcinoma. Severely atypical keratinized squamous cells with necrotic background.
A: Squamous Cell Carcinoma, HPV-associated, of the uterine cervix
Back Extra: Squamous Cell Carcinoma, HPV-associated, of the uterine cervix
- Clinical: The average age at diagnosis in women from high-income countries is in the sixth decade of life (median age: 51 years).
- Micro: Non-keratinizing squamous cell carcinomas are characterized by infiltrative nests of squamous cells without keratinization, while keratinizing variants show presence of keratin pearls.
- Ancillary: Strong and diffuse p16 overexpression is a key finding in almost all HPV-associated squamous cell carcinomas of the uterine cervix.
Reference Gallery:
Non-keratinizing squamous cell carcinoma. This is characterized by infiltrative nests of squamous cells without keratinization.
Non-keratinizing squamous cell carcinoma. Strong and diffuse p16 overexpression is present in almost all HPV-associated squamous cell carcinomas.
Keratinizing squamous cell carcinoma. Keratinizing squamous cell carcinoma shows formation of keratin pearls or marked individual cell keratinization.
Papillary squamous cell carcinoma. The tumour is characterized by the presence of fibrovascular cores lined by multilayered atypical epithelium.
Non-keratinizing squamous cell carcinoma. Cytology: large syncytial aggregates of tumour cells with karrhyorectic debris along the edges (SurePath).
Keratinizing squamous cell carcinoma. Heavily keratinized cells with N:C ratios ranging from low to high, with hyperchromatic nuclei (ThinPrep).
Keratinizing squamous cell carcinoma. Severely atypical keratinized squamous cells with necrotic background.

Q: Histologically, Adenocarcinoma in situ, HPV-associated, of the uterine cervix is characterized by columnar cells with hyperchromatic nuclei, depleted mucin, and characteristic apical mitotic figures often referred to as [...].
Adenocarcinoma in situ. A typical example of adenocarcinoma in situ, with depleted mucin, non-uniform epithelial thickness, variable nuclear spacing, nuclear hyperchromasia, apoptosis, and mitoses.
A: floating mitoses
Back Extra: Adenocarcinoma in situ, HPV-associated, of the uterine cervix
- Clinical: The most common presentation of {{Adenocarcinoma in situ, HPV-associated, of the uterine cervix}} is abnormal cervical cytology showing atypical endocervical glandular cells, often associated with high-grade squamous intraepithelial lesions (HSILs).
- Micro: {{Adenocarcinoma in situ, HPV-associated, of the uterine cervix}} is characterized by columnar cells with depleted mucin, hyperchromatic nuclei, and apical mitotic figures (floating mitoses).
- Ancillary: p16 is overexpressed in nearly all cases of {{Adenocarcinoma in situ, HPV-associated, of the uterine cervix}}, with strong block-type staining.
Reference Gallery:
Adenocarcinoma in situ. A typical example of adenocarcinoma in situ, with depleted mucin, non-uniform epithelial thickness, variable nuclear spacing, nuclear hyperchromasia, apoptosis, and mitoses.
Adenocarcinoma in situ. Adenocarcinoma in situ with intestinal differentiation.
Adenocarcinoma in situ. Adenocarcinoma in situ with more-uniform nuclear features and a pseudostratified epithelium (lower) misleadingly resembling endometrioid differentiation.
Superficial (early) adenocarcinoma in situ. Note the bland appearance of the endocervical papillae. Overt diagnostic nuclear features are seen at the right of the field.
Superficial adenocarcinoma in situ. p16 staining of the field depicted in Fig. #10481 is strong and diffuse.
Superficial (early) adenocarcinoma in situ. Higher magnification of the field shown in Fig. #10481 shows some isolated nuclear atypia but an absence of mitotic activity or apoptosis.
Adenocarcinoma in situ. Intraepithelial, stratified mucinous neoplastic cells constitute stratified mucin-producing intraepithelial lesion.
Adenocarcinoma in situ. p16 shows block-type staining in adenocarcinoma in situ, patchy staining in tuboendometrioid metaplasia (bottom), and no staining in normal endocervical epithelium (right).
Adenocarcinoma in situ. Endocervical adenocarcinoma in situ. A crowded strip of endocervical cells with feathering, palisading, and elongated and irregular nuclei (SurePath).
Adenocarcinoma in situ. Liquid-based cervical cytology shows a cluster of crowded glandular cells with overlapping of hyperchromatic nuclei. Nuclear protrusion at cluster margins (feathering) is a prominent feature.
Adenocarcinoma in situ. Liquid-based cervical cytology shows clusters of crowded glandular cells with loss of the typical endocervical honeycomb pattern and with overlapping of nuclei. The glandular epithelial cells display an increased N:C ratio and obvious feathering.

Q: Immunohistochemistry for p16 in Adenocarcinoma in situ, HPV-associated, of the uterine cervix classically demonstrates [...] staining, which helps differentiate it from the patchy staining seen in normal endocervix or tuboendometrioid metaplasia.
Adenocarcinoma in situ. p16 shows block-type staining in adenocarcinoma in situ, patchy staining in tuboendometrioid metaplasia (bottom), and no staining in normal endocervical epithelium (right).
A: strong block-type
Back Extra: Adenocarcinoma in situ, HPV-associated, of the uterine cervix
- Clinical: The most common presentation of {{Adenocarcinoma in situ, HPV-associated, of the uterine cervix}} is abnormal cervical cytology showing atypical endocervical glandular cells, often associated with high-grade squamous intraepithelial lesions (HSILs).
- Micro: {{Adenocarcinoma in situ, HPV-associated, of the uterine cervix}} is characterized by columnar cells with depleted mucin, hyperchromatic nuclei, and apical mitotic figures (floating mitoses).
- Ancillary: p16 is overexpressed in nearly all cases of {{Adenocarcinoma in situ, HPV-associated, of the uterine cervix}}, with strong block-type staining.
Reference Gallery:
Adenocarcinoma in situ. A typical example of adenocarcinoma in situ, with depleted mucin, non-uniform epithelial thickness, variable nuclear spacing, nuclear hyperchromasia, apoptosis, and mitoses.
Adenocarcinoma in situ. Adenocarcinoma in situ with intestinal differentiation.
Adenocarcinoma in situ. Adenocarcinoma in situ with more-uniform nuclear features and a pseudostratified epithelium (lower) misleadingly resembling endometrioid differentiation.
Superficial (early) adenocarcinoma in situ. Note the bland appearance of the endocervical papillae. Overt diagnostic nuclear features are seen at the right of the field.
Superficial adenocarcinoma in situ. p16 staining of the field depicted in Fig. #10481 is strong and diffuse.
Superficial (early) adenocarcinoma in situ. Higher magnification of the field shown in Fig. #10481 shows some isolated nuclear atypia but an absence of mitotic activity or apoptosis.
Adenocarcinoma in situ. Intraepithelial, stratified mucinous neoplastic cells constitute stratified mucin-producing intraepithelial lesion.
Adenocarcinoma in situ. p16 shows block-type staining in adenocarcinoma in situ, patchy staining in tuboendometrioid metaplasia (bottom), and no staining in normal endocervical epithelium (right).
Adenocarcinoma in situ. Endocervical adenocarcinoma in situ. A crowded strip of endocervical cells with feathering, palisading, and elongated and irregular nuclei (SurePath).
Adenocarcinoma in situ. Liquid-based cervical cytology shows a cluster of crowded glandular cells with overlapping of hyperchromatic nuclei. Nuclear protrusion at cluster margins (feathering) is a prominent feature.
Adenocarcinoma in situ. Liquid-based cervical cytology shows clusters of crowded glandular cells with loss of the typical endocervical honeycomb pattern and with overlapping of nuclei. The glandular epithelial cells display an increased N:C ratio and obvious feathering.

Q: On liquid-based cervical cytology, Adenocarcinoma in situ, HPV-associated, of the uterine cervix typically presents as crowded glandular clusters with hyperchromatic, overlapping nuclei and characteristic nuclear protrusion at the margins, known as [...].
Adenocarcinoma in situ. Liquid-based cervical cytology shows a cluster of crowded glandular cells with overlapping of hyperchromatic nuclei. Nuclear protrusion at cluster margins (feathering) is a prominent feature.
Adenocarcinoma in situ. Liquid-based cervical cytology shows clusters of crowded glandular cells with loss of the typical endocervical honeycomb pattern and with overlapping of nuclei. The glandular epithelial cells display an increased N:C ratio and obvious feathering.
A: feathering
Back Extra: Adenocarcinoma in situ, HPV-associated, of the uterine cervix
- Clinical: The most common presentation of {{Adenocarcinoma in situ, HPV-associated, of the uterine cervix}} is abnormal cervical cytology showing atypical endocervical glandular cells, often associated with high-grade squamous intraepithelial lesions (HSILs).
- Micro: {{Adenocarcinoma in situ, HPV-associated, of the uterine cervix}} is characterized by columnar cells with depleted mucin, hyperchromatic nuclei, and apical mitotic figures (floating mitoses).
- Ancillary: p16 is overexpressed in nearly all cases of {{Adenocarcinoma in situ, HPV-associated, of the uterine cervix}}, with strong block-type staining.
Reference Gallery:
Adenocarcinoma in situ. A typical example of adenocarcinoma in situ, with depleted mucin, non-uniform epithelial thickness, variable nuclear spacing, nuclear hyperchromasia, apoptosis, and mitoses.
Adenocarcinoma in situ. Adenocarcinoma in situ with intestinal differentiation.
Adenocarcinoma in situ. Adenocarcinoma in situ with more-uniform nuclear features and a pseudostratified epithelium (lower) misleadingly resembling endometrioid differentiation.
Superficial (early) adenocarcinoma in situ. Note the bland appearance of the endocervical papillae. Overt diagnostic nuclear features are seen at the right of the field.
Superficial adenocarcinoma in situ. p16 staining of the field depicted in Fig. #10481 is strong and diffuse.
Superficial (early) adenocarcinoma in situ. Higher magnification of the field shown in Fig. #10481 shows some isolated nuclear atypia but an absence of mitotic activity or apoptosis.
Adenocarcinoma in situ. Intraepithelial, stratified mucinous neoplastic cells constitute stratified mucin-producing intraepithelial lesion.
Adenocarcinoma in situ. p16 shows block-type staining in adenocarcinoma in situ, patchy staining in tuboendometrioid metaplasia (bottom), and no staining in normal endocervical epithelium (right).
Adenocarcinoma in situ. Endocervical adenocarcinoma in situ. A crowded strip of endocervical cells with feathering, palisading, and elongated and irregular nuclei (SurePath).
Adenocarcinoma in situ. Liquid-based cervical cytology shows a cluster of crowded glandular cells with overlapping of hyperchromatic nuclei. Nuclear protrusion at cluster margins (feathering) is a prominent feature.
Adenocarcinoma in situ. Liquid-based cervical cytology shows clusters of crowded glandular cells with loss of the typical endocervical honeycomb pattern and with overlapping of nuclei. The glandular epithelial cells display an increased N:C ratio and obvious feathering.

Q: Microscopically, [...] is characterized by cuboidal to columnar cells with distinct cell borders, pale or foamy vacuolated cytoplasm, and varying nuclear atypia (as seen in the gastric-type variant shown).
Gastric-type adenocarcinoma in situ. Note the columnar cells with nuclear atypia.
A: Adenocarcinoma in situ, HPV-independent, of the uterine cervix
Back Extra: Adenocarcinoma in situ, HPV-independent, of the uterine cervix
- Clinical: Adenocarcinoma in situ, HPV-independent, of the uterine cervix can present with abnormal Pap smears or watery discharge and is often found incidentally on hysterectomy or cervical excisions.
- Micro: Characterized by cuboidal to columnar cells with distinct cell borders, eosinophilic to pale and/or foamy vacuolated cytoplasm, and nuclear atypia that ranges from mild to severe.
- Ancillary: Negative/patchy p16 expression, negative HPV testing, and abnormal p53 immunohistochemical staining can support the diagnosis.
Reference Gallery:
Gastric-type adenocarcinoma in situ. Note the columnar cells with nuclear atypia.

Q: Ancillary testing for Adenocarcinoma in situ, HPV-independent, of the uterine cervix classically demonstrates negative or patchy p16 expression, negative HPV testing, and [...] immunohistochemical staining.
Gastric-type adenocarcinoma in situ. Note the columnar cells with nuclear atypia.
A: abnormal p53
Back Extra: Adenocarcinoma in situ, HPV-independent, of the uterine cervix
- Clinical: Adenocarcinoma in situ, HPV-independent, of the uterine cervix can present with abnormal Pap smears or watery discharge and is often found incidentally on hysterectomy or cervical excisions.
- Micro: Characterized by cuboidal to columnar cells with distinct cell borders, eosinophilic to pale and/or foamy vacuolated cytoplasm, and nuclear atypia that ranges from mild to severe.
- Ancillary: Negative/patchy p16 expression, negative HPV testing, and abnormal p53 immunohistochemical staining can support the diagnosis.
Reference Gallery:
Gastric-type adenocarcinoma in situ. Note the columnar cells with nuclear atypia.

Q: Low-grade Squamous Intraepithelial Lesion (CIN 1) is histologically characterized by [...], featuring enlarged, hyperchromatic nuclei surrounded by irregular cytoplasmic halos predominantly in the lower third of the epithelium.
Low-grade squamous intraepithelial lesion (CIN 1). Low-grade squamous intraepithelial lesion (CIN 1) typically demonstrates koilocytic atypia characterized by enlarged, hyperchromatic nuclei surrounded by irregular cytoplasmic halos.
Low-grade squamous intraepithelial lesion (CIN 1). The mucosal surface is notable for koilocytes with enlarged, irregular nuclei and perinuclear haloes.
A: koilocytic atypia
Back Extra: Squamous Intraepithelial Lesion
- Clinical: Cervical Squamous Intraepithelial Lesions (SILs) are asymptomatic and are identified through cytological screening and colposcopy.
- Micro: Low-grade SILs (CIN 1) demonstrate koilocytic atypia and involve the lower third of the epithelium, while high-grade SILs (CIN 2 and CIN 3) show full-thickness basal-type atypia and a high N:C ratio.
- Ancillary: p16 overexpression is a key marker for high-grade SILs, with block-positive staining involving basal keratinocytes and extending beyond the lower third of the epithelium.
Reference Gallery:
High-grade squamous intraepithelial lesion (CIN 3). High-grade squamous intraepithelial lesion involving endocervical glands. High-grade squamous intraepithelial lesion often extends into endocervical glands. This endocervical gland involvement should not be interpreted as invasion.
Low-grade squamous intraepithelial lesion. On cytology, low-grade squamous intraepithelial lesion (CIN 1) cells demonstrate enlarged hyperchromatic nuclei with coarse chromatin and a nuclear size 2–3 times that of a normal intermediate cell. These cells contain abundant cytoplasm, often with a koilocytic halo characterized by an irregular, calligraphy pen–like border.
Low-grade squamous intraepithelial lesion (CIN 1). Low-grade squamous intraepithelial lesion (CIN 1) typically demonstrates koilocytic atypia characterized by enlarged, hyperchromatic nuclei surrounded by irregular cytoplasmic halos.
High-grade squamous intraepithelial lesion (CIN 3). High-grade squamous intraepithelial lesion demonstrates full-thickness basal-type atypia without evidence of maturation.
Low-grade squamous intraepithelial lesion (CIN 1). The mucosal surface is notable for koilocytes with enlarged, irregular nuclei and perinuclear haloes.
Low-grade squamous intraepithelial lesion (CIN 1). p16 staining can be negative (with patchy nuclear and cytoplasmic staining only) or block-positive.
Low-grade squamous intraepithelial lesion (CIN 1). Koilocytes with enlarged, hyperchromatic nuclei and sharply punched-out perinuclear haloes (ThinPrep).
High-grade squamous intraepithelial lesion (CIN 2). Abnormal cells with a high N:C ratio extend above the lower third of the mucosa and exhibit block-positive p16 reactivity (shown in Fig. #13819).
High-grade squamous intraepithelial lesion (CIN 2). Abnormal cells with a high N:C ratio extend above the lower third of the mucosa (see Fig. #13818) and exhibit block-positive p16 reactivity (shown here).
High-grade squamous intraepithelial lesion (CIN 2). The dysplastic cells have a moderately increased N:C ratio (1:1) and nuclei with irregular nuclear contours (ThinPrep Pap).
High-grade squamous intraepithelial lesion (CIN 3). Abnormal cells with a high N:C ratio involve more than two-thirds of the mucosal thickness (see Fig. #16771) and exhibit block-positive p16 reactivity (shown here).
High-grade squamous intraepithelial lesion (CIN 3). Dysplastic cells with a high N:C ratio and irregular, hyperchromatic nuclei (ThinPrep).

Q: High-grade Squamous Intraepithelial Lesion (CIN 3) is distinguished microscopically by the presence of [...] basal-type atypia and a lack of surface maturation.
High-grade squamous intraepithelial lesion (CIN 3). High-grade squamous intraepithelial lesion demonstrates full-thickness basal-type atypia without evidence of maturation.
A: full-thickness
Back Extra: Squamous Intraepithelial Lesion
- Clinical: Cervical Squamous Intraepithelial Lesions (SILs) are asymptomatic and are identified through cytological screening and colposcopy.
- Micro: Low-grade SILs (CIN 1) demonstrate koilocytic atypia and involve the lower third of the epithelium, while high-grade SILs (CIN 2 and CIN 3) show full-thickness basal-type atypia and a high N:C ratio.
- Ancillary: p16 overexpression is a key marker for high-grade SILs, with block-positive staining involving basal keratinocytes and extending beyond the lower third of the epithelium.
Reference Gallery:
High-grade squamous intraepithelial lesion (CIN 3). High-grade squamous intraepithelial lesion involving endocervical glands. High-grade squamous intraepithelial lesion often extends into endocervical glands. This endocervical gland involvement should not be interpreted as invasion.
Low-grade squamous intraepithelial lesion. On cytology, low-grade squamous intraepithelial lesion (CIN 1) cells demonstrate enlarged hyperchromatic nuclei with coarse chromatin and a nuclear size 2–3 times that of a normal intermediate cell. These cells contain abundant cytoplasm, often with a koilocytic halo characterized by an irregular, calligraphy pen–like border.
Low-grade squamous intraepithelial lesion (CIN 1). Low-grade squamous intraepithelial lesion (CIN 1) typically demonstrates koilocytic atypia characterized by enlarged, hyperchromatic nuclei surrounded by irregular cytoplasmic halos.
High-grade squamous intraepithelial lesion (CIN 3). High-grade squamous intraepithelial lesion demonstrates full-thickness basal-type atypia without evidence of maturation.
Low-grade squamous intraepithelial lesion (CIN 1). The mucosal surface is notable for koilocytes with enlarged, irregular nuclei and perinuclear haloes.
Low-grade squamous intraepithelial lesion (CIN 1). p16 staining can be negative (with patchy nuclear and cytoplasmic staining only) or block-positive.
Low-grade squamous intraepithelial lesion (CIN 1). Koilocytes with enlarged, hyperchromatic nuclei and sharply punched-out perinuclear haloes (ThinPrep).
High-grade squamous intraepithelial lesion (CIN 2). Abnormal cells with a high N:C ratio extend above the lower third of the mucosa and exhibit block-positive p16 reactivity (shown in Fig. #13819).
High-grade squamous intraepithelial lesion (CIN 2). Abnormal cells with a high N:C ratio extend above the lower third of the mucosa (see Fig. #13818) and exhibit block-positive p16 reactivity (shown here).
High-grade squamous intraepithelial lesion (CIN 2). The dysplastic cells have a moderately increased N:C ratio (1:1) and nuclei with irregular nuclear contours (ThinPrep Pap).
High-grade squamous intraepithelial lesion (CIN 3). Abnormal cells with a high N:C ratio involve more than two-thirds of the mucosal thickness (see Fig. #16771) and exhibit block-positive p16 reactivity (shown here).
High-grade squamous intraepithelial lesion (CIN 3). Dysplastic cells with a high N:C ratio and irregular, hyperchromatic nuclei (ThinPrep).

Q: Immunohistochemistry for [...] is a key ancillary marker for diagnosing a high-grade Squamous Intraepithelial Lesion, typically demonstrating a strong, block-positive staining pattern.
High-grade squamous intraepithelial lesion (CIN 2). Abnormal cells with a high N:C ratio extend above the lower third of the mucosa (see Fig. #13818) and exhibit block-positive p16 reactivity (shown here).
High-grade squamous intraepithelial lesion (CIN 3). Abnormal cells with a high N:C ratio involve more than two-thirds of the mucosal thickness (see Fig. #16771) and exhibit block-positive p16 reactivity (shown here).
A: p16
Back Extra: Squamous Intraepithelial Lesion
- Clinical: Cervical Squamous Intraepithelial Lesions (SILs) are asymptomatic and are identified through cytological screening and colposcopy.
- Micro: Low-grade SILs (CIN 1) demonstrate koilocytic atypia and involve the lower third of the epithelium, while high-grade SILs (CIN 2 and CIN 3) show full-thickness basal-type atypia and a high N:C ratio.
- Ancillary: p16 overexpression is a key marker for high-grade SILs, with block-positive staining involving basal keratinocytes and extending beyond the lower third of the epithelium.
Reference Gallery:
High-grade squamous intraepithelial lesion (CIN 3). High-grade squamous intraepithelial lesion involving endocervical glands. High-grade squamous intraepithelial lesion often extends into endocervical glands. This endocervical gland involvement should not be interpreted as invasion.
Low-grade squamous intraepithelial lesion. On cytology, low-grade squamous intraepithelial lesion (CIN 1) cells demonstrate enlarged hyperchromatic nuclei with coarse chromatin and a nuclear size 2–3 times that of a normal intermediate cell. These cells contain abundant cytoplasm, often with a koilocytic halo characterized by an irregular, calligraphy pen–like border.
Low-grade squamous intraepithelial lesion (CIN 1). Low-grade squamous intraepithelial lesion (CIN 1) typically demonstrates koilocytic atypia characterized by enlarged, hyperchromatic nuclei surrounded by irregular cytoplasmic halos.
High-grade squamous intraepithelial lesion (CIN 3). High-grade squamous intraepithelial lesion demonstrates full-thickness basal-type atypia without evidence of maturation.
Low-grade squamous intraepithelial lesion (CIN 1). The mucosal surface is notable for koilocytes with enlarged, irregular nuclei and perinuclear haloes.
Low-grade squamous intraepithelial lesion (CIN 1). p16 staining can be negative (with patchy nuclear and cytoplasmic staining only) or block-positive.
Low-grade squamous intraepithelial lesion (CIN 1). Koilocytes with enlarged, hyperchromatic nuclei and sharply punched-out perinuclear haloes (ThinPrep).
High-grade squamous intraepithelial lesion (CIN 2). Abnormal cells with a high N:C ratio extend above the lower third of the mucosa and exhibit block-positive p16 reactivity (shown in Fig. #13819).
High-grade squamous intraepithelial lesion (CIN 2). Abnormal cells with a high N:C ratio extend above the lower third of the mucosa (see Fig. #13818) and exhibit block-positive p16 reactivity (shown here).
High-grade squamous intraepithelial lesion (CIN 2). The dysplastic cells have a moderately increased N:C ratio (1:1) and nuclei with irregular nuclear contours (ThinPrep Pap).
High-grade squamous intraepithelial lesion (CIN 3). Abnormal cells with a high N:C ratio involve more than two-thirds of the mucosal thickness (see Fig. #16771) and exhibit block-positive p16 reactivity (shown here).
High-grade squamous intraepithelial lesion (CIN 3). Dysplastic cells with a high N:C ratio and irregular, hyperchromatic nuclei (ThinPrep).

Q: When involving the female genital tract (e.g., fallopian tube), Diffuse Large B-Cell Lymphoma is characterized by a diffuse infiltrate of large, atypical neoplastic cells with readily identified mitotic figures that strongly express the pan-B-cell marker [...].
Diffuse large B-cell lymphoma involving fallopian tube. Neoplastic cells are large and atypical. Mitotic figures are readily identified.
Diffuse large B-cell lymphoma involving fallopian tube. Immunostaining for CD20 is diffusely positive. This lymphoma had a non–germinal-centre B-cell immunophenotype. FISH showed rearrangement of BCL6, but not of MYC or BCL2.
A: CD20
Back Extra: Diffuse Large B-Cell Lymphoma
- Clinical: Patients often present with symptoms related to a mass or abnormal vaginal bleeding. Ovarian lymphomas may be associated with ascites.
- Micro: Ovarian DLBCL invades diffusely, sparing the ovarian surface and (often) normal structures. Neoplastic cells are large, atypical, and may grow in cords and nests.
- Ancillary: Molecular studies for IG gene rearrangement or MYD88 mutation (p.Leu265Pro) can be helpful. The Ki-67 proliferation index is usually > 50%.
Reference Gallery:
Diffuse large B-cell lymphoma involving fallopian tube. Lymphoma invades and replaces most of the tube; ovaries and other pelvic structures were also involved.
Diffuse large B-cell lymphoma involving fallopian tube. Neoplastic cells are large and atypical. Mitotic figures are readily identified.
Diffuse large B-cell lymphoma involving fallopian tube. Immunostaining for CD20 is diffusely positive. This lymphoma had a non–germinal-centre B-cell immunophenotype. FISH showed rearrangement of BCL6, but not of MYC or BCL2.

Q: A patient presents with a pelvic mass replacing the fallopian tube. Microscopy reveals a diffuse infiltrate of large, atypical lymphoid cells that are diffusely positive for CD20. This clinicopathologic profile is diagnostic of [...].
Diffuse large B-cell lymphoma involving fallopian tube. Lymphoma invades and replaces most of the tube; ovaries and other pelvic structures were also involved.
Diffuse large B-cell lymphoma involving fallopian tube. Neoplastic cells are large and atypical. Mitotic figures are readily identified.
Diffuse large B-cell lymphoma involving fallopian tube. Immunostaining for CD20 is diffusely positive. This lymphoma had a non–germinal-centre B-cell immunophenotype. FISH showed rearrangement of BCL6, but not of MYC or BCL2.
A: Diffuse Large B-Cell Lymphoma
Back Extra: Diffuse Large B-Cell Lymphoma
- Clinical: Patients often present with symptoms related to a mass or abnormal vaginal bleeding. Ovarian lymphomas may be associated with ascites.
- Micro: Ovarian DLBCL invades diffusely, sparing the ovarian surface and (often) normal structures. Neoplastic cells are large, atypical, and may grow in cords and nests.
- Ancillary: Molecular studies for IG gene rearrangement or MYD88 mutation (p.Leu265Pro) can be helpful. The Ki-67 proliferation index is usually > 50%.
Reference Gallery:
Diffuse large B-cell lymphoma involving fallopian tube. Lymphoma invades and replaces most of the tube; ovaries and other pelvic structures were also involved.
Diffuse large B-cell lymphoma involving fallopian tube. Neoplastic cells are large and atypical. Mitotic figures are readily identified.
Diffuse large B-cell lymphoma involving fallopian tube. Immunostaining for CD20 is diffusely positive. This lymphoma had a non–germinal-centre B-cell immunophenotype. FISH showed rearrangement of BCL6, but not of MYC or BCL2.

Q: In cases of Diffuse Large B-Cell Lymphoma demonstrating a non-germinal-center immunophenotype, fluorescence in situ hybridization (FISH) may be utilized to identify characteristic genetic abnormalities, such as the rearrangement of the [...] gene.
Diffuse large B-cell lymphoma involving fallopian tube. Immunostaining for CD20 is diffusely positive. This lymphoma had a non–germinal-centre B-cell immunophenotype. FISH showed rearrangement of BCL6, but not of MYC or BCL2.
A: BCL6
Back Extra: Diffuse Large B-Cell Lymphoma
- Clinical: Patients often present with symptoms related to a mass or abnormal vaginal bleeding. Ovarian lymphomas may be associated with ascites.
- Micro: Ovarian DLBCL invades diffusely, sparing the ovarian surface and (often) normal structures. Neoplastic cells are large, atypical, and may grow in cords and nests.
- Ancillary: Molecular studies for IG gene rearrangement or MYD88 mutation (p.Leu265Pro) can be helpful. The Ki-67 proliferation index is usually > 50%.
Reference Gallery:
Diffuse large B-cell lymphoma involving fallopian tube. Lymphoma invades and replaces most of the tube; ovaries and other pelvic structures were also involved.
Diffuse large B-cell lymphoma involving fallopian tube. Neoplastic cells are large and atypical. Mitotic figures are readily identified.
Diffuse large B-cell lymphoma involving fallopian tube. Immunostaining for CD20 is diffusely positive. This lymphoma had a non–germinal-centre B-cell immunophenotype. FISH showed rearrangement of BCL6, but not of MYC or BCL2.

Q: A reactive lesion characterized by loose intersecting fascicles of spindle-shaped cells, background edema, delicate blood vessels, and scattered chronic inflammatory cells, which classically develops within a few weeks at a prior surgical site, is known as a [...].
Postoperative spindle cell nodule. A relatively cellular spindle cell proliferation is present under the vulvar squamous epithelium. It is associated with background oedema, delicate vasculature, and inflammatory infiltrate.
Postoperative spindle cell nodule. The tumour cells are spindle, with abundant pale cytoplasm and elongated nuclei with vesicular chromatin (and some with nucleoli). Mitotic activity is present.
A: postoperative spindle cell nodule
Back Extra: Postoperative Spindle Cell Nodule
- Clinical: Postoperative spindle cell nodule typically develops at a site of prior procedure, within a few weeks after surgery, and is common in patients of reproductive age.
- Micro: The lesion is composed of loose intersecting fascicles of spindle-shaped cells with eosinophilic to amphophilic cytoplasm, in a variably oedematous stroma, with a delicate network of small blood vessels and chronic inflammatory cells.
- Ancillary: Not clinically relevant; the diagnosis is primarily based on histopathological findings.
Reference Gallery:
Postoperative spindle cell nodule. A relatively cellular spindle cell proliferation is present under the vulvar squamous epithelium. It is associated with background oedema, delicate vasculature, and inflammatory infiltrate.
Postoperative spindle cell nodule. The tumour cells are spindle, with abundant pale cytoplasm and elongated nuclei with vesicular chromatin (and some with nucleoli). Mitotic activity is present.

Q: The embryonal variant of Rhabdomyosarcoma is classically characterized by a subepithelial hypercellular zone known as the [...], which often lies above hypocellular myxoid areas.
Embryonal rhabdomyosarcoma. Embryonal rhabdomyosarcoma exhibiting a hypercellular cambium layer beneath an attenuated epithelium and less-cellular myxoid area.
A: cambium layer
Back Extra: Rhabdomyosarcoma
- Clinical: Patients with rhabdomyosarcomas often present with bleeding and a mass on pelvic examination, which may have a polypoid or botryoid appearance.
- Micro: Embryonal rhabdomyosarcoma (ERMS) is characterized by a hypercellular cambium layer and alternating cellularity with myxoid areas, while alveolar rhabdomyosarcoma (ARMS) shows small round blue cells in nests separated by fibrous septa.
- Ancillary: Immunohistochemistry is positive for myogenin and MYOD1, with more diffuse expression in ARMS than ERMS.
Reference Gallery:
Embryonal rhabdomyosarcoma. Embryonal rhabdomyosarcoma exhibiting a hypercellular cambium layer beneath an attenuated epithelium and less-cellular myxoid area.
Embryonal rhabdomyosarcoma. Embryonal rhabdomyosarcoma composed of hyperchromatic round to spindled cells with scant cytoplasm.
Embryonal rhabdomyosarcoma. Embryonal rhabdomyosarcoma demonstrating nuclear immunoreactivity for myogenin.
Alveolar rhabdomyosarcoma. Alveolar rhabdomyosarcoma composed of nests of rounds cells with eosinophilic cytoplasm separated by fibrous septa.
Botryoid embryonal rhabdomyosarcoma. The tumour shows multiple finger-like projections and minimally infiltrates the myometrium. There is prominent oedema and an only subtle cambium layer under surface epithelium.
Embryonal rhabdomyosarcoma. There are alternating hypercellular and hypocellular areas. Cells are hyperchromatic with scant cytoplasm.
Pleomorphic rhabdomyosarcoma. Tumour cells show significant pleomorphism, and some are multinucleated. Rhabdomyoblastic differentiation is seen.

Q: The alveolar variant of Rhabdomyosarcoma microscopically demonstrates nests of round cells with eosinophilic cytoplasm that are characteristically separated by [...].
Alveolar rhabdomyosarcoma. Alveolar rhabdomyosarcoma composed of nests of rounds cells with eosinophilic cytoplasm separated by fibrous septa.
A: fibrous septa
Back Extra: Rhabdomyosarcoma
- Clinical: Patients with rhabdomyosarcomas often present with bleeding and a mass on pelvic examination, which may have a polypoid or botryoid appearance.
- Micro: Embryonal rhabdomyosarcoma (ERMS) is characterized by a hypercellular cambium layer and alternating cellularity with myxoid areas, while alveolar rhabdomyosarcoma (ARMS) shows small round blue cells in nests separated by fibrous septa.
- Ancillary: Immunohistochemistry is positive for myogenin and MYOD1, with more diffuse expression in ARMS than ERMS.
Reference Gallery:
Embryonal rhabdomyosarcoma. Embryonal rhabdomyosarcoma exhibiting a hypercellular cambium layer beneath an attenuated epithelium and less-cellular myxoid area.
Embryonal rhabdomyosarcoma. Embryonal rhabdomyosarcoma composed of hyperchromatic round to spindled cells with scant cytoplasm.
Embryonal rhabdomyosarcoma. Embryonal rhabdomyosarcoma demonstrating nuclear immunoreactivity for myogenin.
Alveolar rhabdomyosarcoma. Alveolar rhabdomyosarcoma composed of nests of rounds cells with eosinophilic cytoplasm separated by fibrous septa.
Botryoid embryonal rhabdomyosarcoma. The tumour shows multiple finger-like projections and minimally infiltrates the myometrium. There is prominent oedema and an only subtle cambium layer under surface epithelium.
Embryonal rhabdomyosarcoma. There are alternating hypercellular and hypocellular areas. Cells are hyperchromatic with scant cytoplasm.
Pleomorphic rhabdomyosarcoma. Tumour cells show significant pleomorphism, and some are multinucleated. Rhabdomyoblastic differentiation is seen.

Q: Immunohistochemical evaluation of Rhabdomyosarcoma characteristically demonstrates distinct nuclear positivity for MYOD1 and [...].
Embryonal rhabdomyosarcoma. Embryonal rhabdomyosarcoma demonstrating nuclear immunoreactivity for myogenin.
A: myogenin
Back Extra: Rhabdomyosarcoma
- Clinical: Patients with rhabdomyosarcomas often present with bleeding and a mass on pelvic examination, which may have a polypoid or botryoid appearance.
- Micro: Embryonal rhabdomyosarcoma (ERMS) is characterized by a hypercellular cambium layer and alternating cellularity with myxoid areas, while alveolar rhabdomyosarcoma (ARMS) shows small round blue cells in nests separated by fibrous septa.
- Ancillary: Immunohistochemistry is positive for myogenin and MYOD1, with more diffuse expression in ARMS than ERMS.
Reference Gallery:
Embryonal rhabdomyosarcoma. Embryonal rhabdomyosarcoma exhibiting a hypercellular cambium layer beneath an attenuated epithelium and less-cellular myxoid area.
Embryonal rhabdomyosarcoma. Embryonal rhabdomyosarcoma composed of hyperchromatic round to spindled cells with scant cytoplasm.
Embryonal rhabdomyosarcoma. Embryonal rhabdomyosarcoma demonstrating nuclear immunoreactivity for myogenin.
Alveolar rhabdomyosarcoma. Alveolar rhabdomyosarcoma composed of nests of rounds cells with eosinophilic cytoplasm separated by fibrous septa.
Botryoid embryonal rhabdomyosarcoma. The tumour shows multiple finger-like projections and minimally infiltrates the myometrium. There is prominent oedema and an only subtle cambium layer under surface epithelium.
Embryonal rhabdomyosarcoma. There are alternating hypercellular and hypocellular areas. Cells are hyperchromatic with scant cytoplasm.
Pleomorphic rhabdomyosarcoma. Tumour cells show significant pleomorphism, and some are multinucleated. Rhabdomyoblastic differentiation is seen.

Q: In NTRK-rearranged Spindle Cell Neoplasm, the tumor cells typically demonstrate diffuse immunohistochemical positivity for [...], alongside frequent co-expression of S100 and CD34.
NTRK-rearranged sarcoma. These tumours show diffuse positivity for TRK.
NTRK-rearranged sarcoma. This tumour is positive for S100.
NTRK-rearranged sarcoma. These tumours are often positive for CD34.
A: TRK
Back Extra: NTRK-rearranged Spindle Cell Neoplasm
- Clinical: Most patients present with vaginal bleeding or a cervical mass. Patients with NTRK-rearranged cervical sarcoma range in age from 23 to 44 years (mean: 31 years).
- Micro: NTRK-rearranged cervical sarcoma consists of a proliferation of predominantly uniform spindle cells with mild to moderate atypia and inconspicuous nucleoli. A staghorn vascular pattern and necrosis may be present.
- Ancillary: Positive for S100, CD34, TRK, and cyclin D1. Demonstration of NTRK rearrangement is diagnostic.
Reference Gallery:
NTRK-rearranged sarcoma. These tumours show diffuse positivity for TRK.
NTRK-rearranged sarcoma. NTRK-rearranged cervical neoplasm exhibits haphazard spindle cells with mild atypia.
NTRK-rearranged sarcoma. This tumour is positive for S100.
NTRK-rearranged sarcoma. These tumours are often positive for CD34.

Q: Microscopically, NTRK-rearranged Spindle Cell Neoplasm is a cervical tumor that features a proliferation of haphazard spindle cells with mild atypia, often displaying a characteristic [...] vascular pattern.
NTRK-rearranged sarcoma. NTRK-rearranged cervical neoplasm exhibits haphazard spindle cells with mild atypia.
A: staghorn
Back Extra: NTRK-rearranged Spindle Cell Neoplasm
- Clinical: Most patients present with vaginal bleeding or a cervical mass. Patients with NTRK-rearranged cervical sarcoma range in age from 23 to 44 years (mean: 31 years).
- Micro: NTRK-rearranged cervical sarcoma consists of a proliferation of predominantly uniform spindle cells with mild to moderate atypia and inconspicuous nucleoli. A staghorn vascular pattern and necrosis may be present.
- Ancillary: Positive for S100, CD34, TRK, and cyclin D1. Demonstration of NTRK rearrangement is diagnostic.
Reference Gallery:
NTRK-rearranged sarcoma. These tumours show diffuse positivity for TRK.
NTRK-rearranged sarcoma. NTRK-rearranged cervical neoplasm exhibits haphazard spindle cells with mild atypia.
NTRK-rearranged sarcoma. This tumour is positive for S100.
NTRK-rearranged sarcoma. These tumours are often positive for CD34.

Q: In Metastasis to the Lower Female Genital Tract, histologic features that strongly suggest a metastatic origin rather than a primary tumor include extensive lymphovascular invasion, the lack of an in situ component, and the presence of [...] cells.
Metastasis of poorly differentiated gastric adenocarcinoma to cervix and endometrium. Small nests of tumour cells lie in the cervical stroma.
Metastasis of poorly differentiated gastric adenocarcinoma to cervix and endometrium. Small nests of tumour cells are present in the cervical stroma, particularly around the blood vessels, showing focal signet-ring morphology.
A: signet-ring
Back Extra: Metastasis to the Lower Female Genital Tract
- Clinical: Patients with metastasis to the lower female genital tract may present with bleeding, abnormal cervical cytology, or a mass accompanied by ulceration or pain.
- Micro: Features suggesting metastasis to the cervix include signet-ring cells, lack of an in situ component, and extensive lymphovascular invasion.
- Ancillary: Immunohistochemistry may help to confirm the diagnosis and the origin of the metastasis.
Reference Gallery:
Metastasis of poorly differentiated gastric adenocarcinoma to cervix and endometrium. Small nests of tumour cells lie in the cervical stroma.
Metastasis of poorly differentiated gastric adenocarcinoma to cervix and endometrium. Small nests of tumour cells are present in the cervical stroma, particularly around the blood vessels, showing focal signet-ring morphology.
Metastasis of poorly differentiated gastric adenocarcinoma to cervix and endometrium. Small nests of tumour cells are present in the endometrial stroma.
Metastasis of poorly differentiated gastric adenocarcinoma to cervix and endometrium. The tumour cells are arranged in cords and small glands.
Metastasis of invasive breast carcinoma of no special type (NST) to a leiomyoma in the uterus. Low-power view.
Metastasis of invasive breast carcinoma of no special type (NST) to a leiomyoma in the uterus. The tumour cells are arranged in clusters and trabeculae in the uterine leiomyoma, with a large necrotic area centrally.
Metastasis of invasive breast carcinoma of no special type (NST) to a leiomyoma in the uterus. The tumour cells are immunoreactive for GATA3.
Metastasis of colonic adenocarcinoma to cervix. Cervical biopsy taken for abnormal cervical cytology. Cervical tissue is infiltrated by adenocarcinoma extending to overlying stratified squamous epithelium.
Metastasis of colonic adenocarcinoma to cervix. The invasive adenocarcinoma infiltrates between normal endocervical glands. Origin from colonic carcinoma was confirmed by immunohistochemistry and clinical investigation.
Metastasis of lobular breast carcinoma to endometrium. Endometrial curettage performed for abnormal uterine bleeding in a patient without known breast cancer. The endometrial stroma is infiltrated by dyscohesive round atypical cells with eccentric nuclei. Origin from lobular breast carcinoma was confirmed by immunohistochemistry and clinical investigation.

Q: When evaluating Metastasis to the Lower Female Genital Tract, infiltration of the stroma by dyscohesive, single, round atypical cells with eccentric nuclei is highly characteristic of a metastasis from a primary [...].
Metastasis of lobular breast carcinoma to endometrium. Endometrial curettage performed for abnormal uterine bleeding in a patient without known breast cancer. The endometrial stroma is infiltrated by dyscohesive round atypical cells with eccentric nuclei. Origin from lobular breast carcinoma was confirmed by immunohistochemistry and clinical investigation.
A: lobular breast carcinoma
Back Extra: Metastasis to the Lower Female Genital Tract
- Clinical: Patients with metastasis to the lower female genital tract may present with bleeding, abnormal cervical cytology, or a mass accompanied by ulceration or pain.
- Micro: Features suggesting metastasis to the cervix include signet-ring cells, lack of an in situ component, and extensive lymphovascular invasion.
- Ancillary: Immunohistochemistry may help to confirm the diagnosis and the origin of the metastasis.
Reference Gallery:
Metastasis of poorly differentiated gastric adenocarcinoma to cervix and endometrium. Small nests of tumour cells lie in the cervical stroma.
Metastasis of poorly differentiated gastric adenocarcinoma to cervix and endometrium. Small nests of tumour cells are present in the cervical stroma, particularly around the blood vessels, showing focal signet-ring morphology.
Metastasis of poorly differentiated gastric adenocarcinoma to cervix and endometrium. Small nests of tumour cells are present in the endometrial stroma.
Metastasis of poorly differentiated gastric adenocarcinoma to cervix and endometrium. The tumour cells are arranged in cords and small glands.
Metastasis of invasive breast carcinoma of no special type (NST) to a leiomyoma in the uterus. Low-power view.
Metastasis of invasive breast carcinoma of no special type (NST) to a leiomyoma in the uterus. The tumour cells are arranged in clusters and trabeculae in the uterine leiomyoma, with a large necrotic area centrally.
Metastasis of invasive breast carcinoma of no special type (NST) to a leiomyoma in the uterus. The tumour cells are immunoreactive for GATA3.
Metastasis of colonic adenocarcinoma to cervix. Cervical biopsy taken for abnormal cervical cytology. Cervical tissue is infiltrated by adenocarcinoma extending to overlying stratified squamous epithelium.
Metastasis of colonic adenocarcinoma to cervix. The invasive adenocarcinoma infiltrates between normal endocervical glands. Origin from colonic carcinoma was confirmed by immunohistochemistry and clinical investigation.
Metastasis of lobular breast carcinoma to endometrium. Endometrial curettage performed for abnormal uterine bleeding in a patient without known breast cancer. The endometrial stroma is infiltrated by dyscohesive round atypical cells with eccentric nuclei. Origin from lobular breast carcinoma was confirmed by immunohistochemistry and clinical investigation.

Q: A diagnosis of Metastasis to the Lower Female Genital Tract originating from a primary breast carcinoma (e.g., spreading to a uterine leiomyoma) can be immunohistochemically confirmed by positivity for markers such as [...].
Metastasis of invasive breast carcinoma of no special type (NST) to a leiomyoma in the uterus. The tumour cells are arranged in clusters and trabeculae in the uterine leiomyoma, with a large necrotic area centrally.
Metastasis of invasive breast carcinoma of no special type (NST) to a leiomyoma in the uterus. The tumour cells are immunoreactive for GATA3.
A: GATA3
Back Extra: Metastasis to the Lower Female Genital Tract
- Clinical: Patients with metastasis to the lower female genital tract may present with bleeding, abnormal cervical cytology, or a mass accompanied by ulceration or pain.
- Micro: Features suggesting metastasis to the cervix include signet-ring cells, lack of an in situ component, and extensive lymphovascular invasion.
- Ancillary: Immunohistochemistry may help to confirm the diagnosis and the origin of the metastasis.
Reference Gallery:
Metastasis of poorly differentiated gastric adenocarcinoma to cervix and endometrium. Small nests of tumour cells lie in the cervical stroma.
Metastasis of poorly differentiated gastric adenocarcinoma to cervix and endometrium. Small nests of tumour cells are present in the cervical stroma, particularly around the blood vessels, showing focal signet-ring morphology.
Metastasis of poorly differentiated gastric adenocarcinoma to cervix and endometrium. Small nests of tumour cells are present in the endometrial stroma.
Metastasis of poorly differentiated gastric adenocarcinoma to cervix and endometrium. The tumour cells are arranged in cords and small glands.
Metastasis of invasive breast carcinoma of no special type (NST) to a leiomyoma in the uterus. Low-power view.
Metastasis of invasive breast carcinoma of no special type (NST) to a leiomyoma in the uterus. The tumour cells are arranged in clusters and trabeculae in the uterine leiomyoma, with a large necrotic area centrally.
Metastasis of invasive breast carcinoma of no special type (NST) to a leiomyoma in the uterus. The tumour cells are immunoreactive for GATA3.
Metastasis of colonic adenocarcinoma to cervix. Cervical biopsy taken for abnormal cervical cytology. Cervical tissue is infiltrated by adenocarcinoma extending to overlying stratified squamous epithelium.
Metastasis of colonic adenocarcinoma to cervix. The invasive adenocarcinoma infiltrates between normal endocervical glands. Origin from colonic carcinoma was confirmed by immunohistochemistry and clinical investigation.
Metastasis of lobular breast carcinoma to endometrium. Endometrial curettage performed for abnormal uterine bleeding in a patient without known breast cancer. The endometrial stroma is infiltrated by dyscohesive round atypical cells with eccentric nuclei. Origin from lobular breast carcinoma was confirmed by immunohistochemistry and clinical investigation.

Q: Histologically, a well-circumscribed nodule composed of widely spaced, cystically dilated endocervical-type glands set within a fibromuscular (smooth muscle-rich) stroma is the defining hallmark of [...].
Adenomyoma. The lesion shows widely spaced glands within smooth muscle–rich stroma. Some glands are cystically dilated; others are arranged in small lobules. Intraglandular papillary infoldings are seen.
A: Adenomyoma of the Uterine Cervix
Back Extra: Adenomyoma of the Uterine Cervix
- Clinical: Patients are often asymptomatic or may present with a mass, vaginal discharge, or bleeding; mean age at presentation is 40 years.
- Micro: Histopathology reveals a well-circumscribed nodule with cystically dilated or widely spaced glands forming lobules, lined by endocervical-type epithelium, and a fibromuscular stroma.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis.
Reference Gallery:
Adenomyoma. The lesion shows widely spaced glands within smooth muscle–rich stroma. Some glands are cystically dilated; others are arranged in small lobules. Intraglandular papillary infoldings are seen.

Q: In cervical Atrophy, the epithelium is typically only a few cell layers thick and is composed of [...] without maturation.
Cervical atrophy. Cytological appearance of atrophy.
Atrophy. The epithelium is only a few cell layers thick and is composed of parabasal cells without maturation.
A: parabasal cells
Back Extra: Atrophy
- Clinical: Cervical atrophy is often asymptomatic or associated with symptoms of vaginal atrophy.
- Micro: The epithelium in atrophy is only a few cell layers thick, composed of parabasal cells without maturation.
- Ancillary: Atrophic epithelium is p16-negative and shows a low Ki-67 proliferation index.
Reference Gallery:
Cervical atrophy. Cytological appearance of atrophy.
Atrophy. The epithelium is only a few cell layers thick and is composed of parabasal cells without maturation.
Atrophy. P16 immunohistochemistry is negative.

Q: To distinguish cervical Atrophy from dysplasia, ancillary testing is useful because atrophic epithelium shows a low Ki-67 index and is classically negative for [...].
Atrophy. P16 immunohistochemistry is negative.
A: p16
Back Extra: Atrophy
- Clinical: Cervical atrophy is often asymptomatic or associated with symptoms of vaginal atrophy.
- Micro: The epithelium in atrophy is only a few cell layers thick, composed of parabasal cells without maturation.
- Ancillary: Atrophic epithelium is p16-negative and shows a low Ki-67 proliferation index.
Reference Gallery:
Cervical atrophy. Cytological appearance of atrophy.
Atrophy. The epithelium is only a few cell layers thick and is composed of parabasal cells without maturation.
Atrophy. P16 immunohistochemistry is negative.

Q: In Squamous Metaplasia, the immature variant is characterized by a thick layer of uniform, basaloid cells that characteristically lack [...] deposition.
Squamous metaplasia. Immature squamous metaplasia. Squamous metaplasia involving the endocervical surface and a gland. The thick metaplastic epithelium lacks maturation / glycogen deposition. Note the absence of tall columnar epithelium, mitotic activity, and atypia.
Squamous metaplasia. Mature squamous metaplasia. Thick, non-keratinized, glycogenated squamous epithelium with endocervical glands in the underlying stroma.
A: glycogen
Back Extra: Squamous Metaplasia
- Clinical: Squamous metaplasia is a common, physiological, HPV-independent benign process mainly related to estrogenic stimulation and vaginal pH changes after menarche and during pregnancy.
- Micro: Immature squamous metaplasia is characterized by uniform basaloid cells without glycogen and may be only a few cell layers thick.
- Ancillary: In cases of immature metaplastic epithelium with mild atypia, p16 negativity can help distinguish from thin HSIL.
Reference Gallery:
Squamous metaplasia. This occurs at the transition between mature squamous and endocervical mucosa, and it is characterized by evenly spaced round nuclei and moderate amounts of dense cytoplasm.
Squamous metaplasia. Squamous metaplastic cells have centrally placed round nuclei, dense cytoplasm, and distinct cell borders (ThinPrep Pap).
Squamous metaplasia. Immature squamous metaplasia. Squamous metaplasia involving the endocervical surface and a gland. The thick metaplastic epithelium lacks maturation / glycogen deposition. Note the absence of tall columnar epithelium, mitotic activity, and atypia.
Squamous metaplasia. Mature squamous metaplasia. Thick, non-keratinized, glycogenated squamous epithelium with endocervical glands in the underlying stroma.
Normal endocervical mucosa and reserve cell proliferation. Endocervical mucosa with tall columnar mucinous endocervical cells and a row of basally located reserve cells.
Normal endocervical mucosa and reserve cell proliferation. The row of reserve cells underlying the single row of tall columnar endocervical cells stains with antibody to CK17.
Normal endocervical mucosa and reserve cell proliferation. Individual reserve cells. The first step of squamous metaplasia involves the occurrence of reserve cells below the tall columnar endocervical cells, illustrated by immunohistochemical staining with antibody to p63.
Normal endocervical mucosa and reserve cell proliferation. Reserve cell proliferation. Basally located reserve cells proliferate to form 1–2 rows of cells.

Q: On cervical cytology, cells of Squamous Metaplasia typically present with evenly spaced, centrally placed round nuclei and moderate amounts of [...] cytoplasm with distinct cell borders.
Squamous metaplasia. This occurs at the transition between mature squamous and endocervical mucosa, and it is characterized by evenly spaced round nuclei and moderate amounts of dense cytoplasm.
Squamous metaplasia. Squamous metaplastic cells have centrally placed round nuclei, dense cytoplasm, and distinct cell borders (ThinPrep Pap).
A: dense
Back Extra: Squamous Metaplasia
- Clinical: Squamous metaplasia is a common, physiological, HPV-independent benign process mainly related to estrogenic stimulation and vaginal pH changes after menarche and during pregnancy.
- Micro: Immature squamous metaplasia is characterized by uniform basaloid cells without glycogen and may be only a few cell layers thick.
- Ancillary: In cases of immature metaplastic epithelium with mild atypia, p16 negativity can help distinguish from thin HSIL.
Reference Gallery:
Squamous metaplasia. This occurs at the transition between mature squamous and endocervical mucosa, and it is characterized by evenly spaced round nuclei and moderate amounts of dense cytoplasm.
Squamous metaplasia. Squamous metaplastic cells have centrally placed round nuclei, dense cytoplasm, and distinct cell borders (ThinPrep Pap).
Squamous metaplasia. Immature squamous metaplasia. Squamous metaplasia involving the endocervical surface and a gland. The thick metaplastic epithelium lacks maturation / glycogen deposition. Note the absence of tall columnar epithelium, mitotic activity, and atypia.
Squamous metaplasia. Mature squamous metaplasia. Thick, non-keratinized, glycogenated squamous epithelium with endocervical glands in the underlying stroma.
Normal endocervical mucosa and reserve cell proliferation. Endocervical mucosa with tall columnar mucinous endocervical cells and a row of basally located reserve cells.
Normal endocervical mucosa and reserve cell proliferation. The row of reserve cells underlying the single row of tall columnar endocervical cells stains with antibody to CK17.
Normal endocervical mucosa and reserve cell proliferation. Individual reserve cells. The first step of squamous metaplasia involves the occurrence of reserve cells below the tall columnar endocervical cells, illustrated by immunohistochemical staining with antibody to p63.
Normal endocervical mucosa and reserve cell proliferation. Reserve cell proliferation. Basally located reserve cells proliferate to form 1–2 rows of cells.

Q: The first step in the development of cervical Squamous Metaplasia involves the appearance and proliferation of subcolumnar [...], which can be highlighted by p63 and CK17 immunostaining.
Normal endocervical mucosa and reserve cell proliferation. The row of reserve cells underlying the single row of tall columnar endocervical cells stains with antibody to CK17.
Normal endocervical mucosa and reserve cell proliferation. Individual reserve cells. The first step of squamous metaplasia involves the occurrence of reserve cells below the tall columnar endocervical cells, illustrated by immunohistochemical staining with antibody to p63.
Normal endocervical mucosa and reserve cell proliferation. Reserve cell proliferation. Basally located reserve cells proliferate to form 1–2 rows of cells.
A: reserve cells
Back Extra: Squamous Metaplasia
- Clinical: Squamous metaplasia is a common, physiological, HPV-independent benign process mainly related to estrogenic stimulation and vaginal pH changes after menarche and during pregnancy.
- Micro: Immature squamous metaplasia is characterized by uniform basaloid cells without glycogen and may be only a few cell layers thick.
- Ancillary: In cases of immature metaplastic epithelium with mild atypia, p16 negativity can help distinguish from thin HSIL.
Reference Gallery:
Squamous metaplasia. This occurs at the transition between mature squamous and endocervical mucosa, and it is characterized by evenly spaced round nuclei and moderate amounts of dense cytoplasm.
Squamous metaplasia. Squamous metaplastic cells have centrally placed round nuclei, dense cytoplasm, and distinct cell borders (ThinPrep Pap).
Squamous metaplasia. Immature squamous metaplasia. Squamous metaplasia involving the endocervical surface and a gland. The thick metaplastic epithelium lacks maturation / glycogen deposition. Note the absence of tall columnar epithelium, mitotic activity, and atypia.
Squamous metaplasia. Mature squamous metaplasia. Thick, non-keratinized, glycogenated squamous epithelium with endocervical glands in the underlying stroma.
Normal endocervical mucosa and reserve cell proliferation. Endocervical mucosa with tall columnar mucinous endocervical cells and a row of basally located reserve cells.
Normal endocervical mucosa and reserve cell proliferation. The row of reserve cells underlying the single row of tall columnar endocervical cells stains with antibody to CK17.
Normal endocervical mucosa and reserve cell proliferation. Individual reserve cells. The first step of squamous metaplasia involves the occurrence of reserve cells below the tall columnar endocervical cells, illustrated by immunohistochemical staining with antibody to p63.
Normal endocervical mucosa and reserve cell proliferation. Reserve cell proliferation. Basally located reserve cells proliferate to form 1–2 rows of cells.

Q: In Transitional Cell Metaplasia, the metaplastic epithelium at the tuboperitoneal junction frequently forms distinct structures known as [...].
Transitional cell metaplasia. This metaplastic process is seen at the tuboperitoneal junction, with Walthard nest formation.
A: Walthard nests
Back Extra: Transitional Cell Metaplasia
- Clinical: Transitional cell metaplasia (TCM) is an incidental microscopic finding, typically observed in patients in their fourth to seventh decade of life.
- Micro: TCM consists of bland transitional epithelium with small nucleoli, but lacks nuclear atypia, hyperchromasia, macronucleoli, mitoses, or apoptotic bodies. Microlumina or small cysts with amphophilic material or umbrella-like cells may be present.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis or management of TCM.
Reference Gallery:
Transitional cell metaplasia. This metaplastic process is seen at the tuboperitoneal junction, with Walthard nest formation.

Q: Microscopically, Transitional Cell Metaplasia consists of bland epithelium without nuclear atypia, which may feature microlumina or superficial [...] cells.
Transitional cell metaplasia. This metaplastic process is seen at the tuboperitoneal junction, with Walthard nest formation.
A: umbrella-like
Back Extra: Transitional Cell Metaplasia
- Clinical: Transitional cell metaplasia (TCM) is an incidental microscopic finding, typically observed in patients in their fourth to seventh decade of life.
- Micro: TCM consists of bland transitional epithelium with small nucleoli, but lacks nuclear atypia, hyperchromasia, macronucleoli, mitoses, or apoptotic bodies. Microlumina or small cysts with amphophilic material or umbrella-like cells may be present.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis or management of TCM.
Reference Gallery:
Transitional cell metaplasia. This metaplastic process is seen at the tuboperitoneal junction, with Walthard nest formation.

Q: Histologically, the presence of architecturally normal endocervical glands lined by a mixture of ciliated cells, pseudostratified non-ciliated cells, and intercalated (peg) cells with subtle stromal condensation is characteristic of [...].
Tuboendometrioid metaplasia. Tuboendometrioid metaplasia is characterized by a lack of overt mucinous differentiation and the presence of ciliated and non-ciliated pseudostratified epithelial cells.
Tuboendometrioid metaplasia. Tuboendometrioid glands (right) are present in a background of normal endocervix.
A: Tuboendometrioid Metaplasia
Back Extra: Tuboendometrioid Metaplasia
- Clinical: Tuboendometrioid metaplasia is generally an incidental finding, commonly seen in women of reproductive age and may be associated with previous cervical instrumentation.
- Micro: The lesions are composed of architecturally normal endocervical glands with ciliated cells, pseudostratified non-ciliated cells, and intercalated or peg cells, with typical subtle stromal condensation around the glands.
- Ancillary: While not clinically relevant, ER is invariably positive and p16 shows patchy staining in tuboendometrioid metaplasia.
Reference Gallery:
Tuboendometrioid metaplasia. Tuboendometrioid metaplasia is characterized by a lack of overt mucinous differentiation and the presence of ciliated and non-ciliated pseudostratified epithelial cells.
Tuboendometrioid metaplasia. Tuboendometrioid glands (right) are present in a background of normal endocervix.

Q: Unlike the normal background endocervix, the glands in Tuboendometrioid Metaplasia characteristically lack overt [...].
Tuboendometrioid metaplasia. Tuboendometrioid metaplasia is characterized by a lack of overt mucinous differentiation and the presence of ciliated and non-ciliated pseudostratified epithelial cells.
A: mucinous differentiation
Back Extra: Tuboendometrioid Metaplasia
- Clinical: Tuboendometrioid metaplasia is generally an incidental finding, commonly seen in women of reproductive age and may be associated with previous cervical instrumentation.
- Micro: The lesions are composed of architecturally normal endocervical glands with ciliated cells, pseudostratified non-ciliated cells, and intercalated or peg cells, with typical subtle stromal condensation around the glands.
- Ancillary: While not clinically relevant, ER is invariably positive and p16 shows patchy staining in tuboendometrioid metaplasia.
Reference Gallery:
Tuboendometrioid metaplasia. Tuboendometrioid metaplasia is characterized by a lack of overt mucinous differentiation and the presence of ciliated and non-ciliated pseudostratified epithelial cells.
Tuboendometrioid metaplasia. Tuboendometrioid glands (right) are present in a background of normal endocervix.

Q: Microscopically, the Arias-Stella Reaction is characterized by enlarged glandular cells with clear to eosinophilic cytoplasm and hyperchromatic, pleomorphic nuclei that frequently exhibit a characteristic [...] appearance.
Arias-Stella reaction. Enlarged glandular cells with vacuolated clear cytoplasm and hyperchromatic pleomorphic nuclei with hobnail features.
A: hobnail
Back Extra: Arias-Stella Reaction
- Clinical: Arias-Stella Reaction (ASR) is predominantly an incidental finding, often associated with pregnancy, gestational trophoblastic disease, or high doses of progestins.
- Micro: ASR shows enlarged glandular cells with abundant eosinophilic or glycogen-rich clear cytoplasm and hyperchromatic, pleomorphic nuclei with a hobnail appearance.
- Ancillary: Immunohistochemical stains have limited value in diagnosing ASR, as many markers overlap with those of clear cell carcinoma.
Reference Gallery:
Arias-Stella reaction. Enlarged glandular cells with vacuolated clear cytoplasm and hyperchromatic pleomorphic nuclei with hobnail features.

Q: An incidental finding in the endometrium associated with pregnancy or high-dose progestin therapy shows enlarged glands with clear cytoplasm and hyperchromatic, pleomorphic hobnail nuclei. This benign physiologic change is known as the [...].
Arias-Stella reaction. Enlarged glandular cells with vacuolated clear cytoplasm and hyperchromatic pleomorphic nuclei with hobnail features.
A: Arias-Stella Reaction
Back Extra: Arias-Stella Reaction
- Clinical: Arias-Stella Reaction (ASR) is predominantly an incidental finding, often associated with pregnancy, gestational trophoblastic disease, or high doses of progestins.
- Micro: ASR shows enlarged glandular cells with abundant eosinophilic or glycogen-rich clear cytoplasm and hyperchromatic, pleomorphic nuclei with a hobnail appearance.
- Ancillary: Immunohistochemical stains have limited value in diagnosing ASR, as many markers overlap with those of clear cell carcinoma.
Reference Gallery:
Arias-Stella reaction. Enlarged glandular cells with vacuolated clear cytoplasm and hyperchromatic pleomorphic nuclei with hobnail features.

Q: Microscopically, Ectopic Decidua classically presents as solid growths of [...] with well-delineated borders, variably sized nuclei, and prominent nucleoli.
Ectopic decidua. Polygonal and spindled cells with distinct cell borders and variably sized nuclei.
A: polygonal or spindled cells
Back Extra: Ectopic Decidua
- Clinical: Ectopic decidua is usually an asymptomatic, incidental finding in women of reproductive age, occurring during pregnancy or progestin use.
- Micro: Microscopically, ectopic decidua shows solid growth of polygonal or spindled cells with well-delineated borders, eosinophilic or amphophilic cytoplasm, and nuclei with fine chromatin and prominent nucleoli.
- Ancillary: Immunohistochemical studies show that ectopic decidua cells are positive for ER and PR and typically negative for keratin and calretinin.
Reference Gallery:
Ectopic decidua. Polygonal and spindled cells with distinct cell borders and variably sized nuclei.
Ectopic decidua. Micronodules on the ovarian surface, composed of polygonal and/or spindled cells with distinct cell borders and variably sized nuclei.

Q: Incidental micronodules on the ovarian surface composed of eosinophilic cells with distinct cell borders, typically seen during pregnancy or progestin use, are diagnostic of [...].
Ectopic decidua. Micronodules on the ovarian surface, composed of polygonal and/or spindled cells with distinct cell borders and variably sized nuclei.
A: Ectopic Decidua
Back Extra: Ectopic Decidua
- Clinical: Ectopic decidua is usually an asymptomatic, incidental finding in women of reproductive age, occurring during pregnancy or progestin use.
- Micro: Microscopically, ectopic decidua shows solid growth of polygonal or spindled cells with well-delineated borders, eosinophilic or amphophilic cytoplasm, and nuclei with fine chromatin and prominent nucleoli.
- Ancillary: Immunohistochemical studies show that ectopic decidua cells are positive for ER and PR and typically negative for keratin and calretinin.
Reference Gallery:
Ectopic decidua. Polygonal and spindled cells with distinct cell borders and variably sized nuclei.
Ectopic decidua. Micronodules on the ovarian surface, composed of polygonal and/or spindled cells with distinct cell borders and variably sized nuclei.

Q: Microscopically, a Paratubal Cyst is characteristically lined by cuboidal or [...] epithelium, closely resembling the normal fallopian tube.
Paratubal cyst. Paratubal cyst lined by ciliated epithelium similar to that of the fallopian tube.
A: ciliated
Back Extra: Paratubal Cyst
- Clinical: Paratubal cysts present as adnexal masses or cysts and may become symptomatic if there is rapid enlargement, torsion, rupture, or haemorrhage.
- Micro: Paratubal cysts are lined by cuboidal or ciliated epithelium similar to that of the fallopian tube.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of paratubal cysts.
Reference Gallery:
Paratubal cyst. Cystic structure found near fallopian tube.
Paratubal cyst. Paratubal cyst lined by ciliated epithelium similar to that of the fallopian tube.

Q: An adnexal cystic structure found adjacent to the fallopian tube that may become symptomatic due to rapid enlargement, torsion, rupture, or hemorrhage is most appropriately diagnosed as a [...].
Paratubal cyst. Cystic structure found near fallopian tube.
A: Paratubal Cyst
Back Extra: Paratubal Cyst
- Clinical: Paratubal cysts present as adnexal masses or cysts and may become symptomatic if there is rapid enlargement, torsion, rupture, or haemorrhage.
- Micro: Paratubal cysts are lined by cuboidal or ciliated epithelium similar to that of the fallopian tube.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of paratubal cysts.
Reference Gallery:
Paratubal cyst. Cystic structure found near fallopian tube.
Paratubal cyst. Paratubal cyst lined by ciliated epithelium similar to that of the fallopian tube.

Q: Microscopically, [...] is characterized by discrete foci of pseudostratification and loss of polarity without nuclear atypia or mitotic activity.
Tubal hyperplasia. High-power view of a focus of tubal hyperplasia shows lack of atypia and mitotic activity.
A: Tubal Hyperplasia
Back Extra: Tubal Hyperplasia
- Clinical: Tubal hyperplasia is an incidental finding, often associated with inflammation and mesothelial proliferation.
- Micro: The most common pattern is discrete foci of pseudostratification and loss of polarity without nuclear atypia or mitotic activity.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of tubal hyperplasia.
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Tubal hyperplasia. High-power view of a focus of tubal hyperplasia shows lack of atypia and mitotic activity.

Q: When evaluating Tubal Hyperplasia, it is critical to note that the proliferating, pseudostratified epithelium classically lacks [...] to differentiate it from neoplastic processes.
Tubal hyperplasia. High-power view of a focus of tubal hyperplasia shows lack of atypia and mitotic activity.
A: nuclear atypia and mitotic activity
Back Extra: Tubal Hyperplasia
- Clinical: Tubal hyperplasia is an incidental finding, often associated with inflammation and mesothelial proliferation.
- Micro: The most common pattern is discrete foci of pseudostratification and loss of polarity without nuclear atypia or mitotic activity.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of tubal hyperplasia.
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Tubal hyperplasia. High-power view of a focus of tubal hyperplasia shows lack of atypia and mitotic activity.

Q: Salpingitis Isthmica Nodosa is characterized microscopically by dilated, ciliated glandular structures within the fallopian tube that are uniquely surrounded by [...].
Salpingitis isthmica nodosa. A central dilated lumen with surrounding gland-like structures and hypertrophic smooth muscle.
A: hypertrophic smooth muscle
Back Extra: Salpingitis Isthmica Nodosa
- Clinical: Salpingitis isthmica nodosa is strongly associated with infertility and ectopic pregnancy.
- Micro: The isthmic/proximal segment of the tube shows variably sized, dilated glandular structures lined by ciliated, columnar epithelium, surrounded by hypertrophic muscle.
- Ancillary: No specific ancillary studies are clinically relevant for the diagnosis of Salpingitis isthmica nodosa.
Reference Gallery:
Salpingitis isthmica nodosa. A central dilated lumen with surrounding gland-like structures and hypertrophic smooth muscle.

Q: [...] is a benign tubal lesion histologically demonstrating a central dilated lumen with surrounding gland-like structures, and is strongly associated clinically with infertility and ectopic pregnancy.
Salpingitis isthmica nodosa. A central dilated lumen with surrounding gland-like structures and hypertrophic smooth muscle.
A: Salpingitis Isthmica Nodosa
Back Extra: Salpingitis Isthmica Nodosa
- Clinical: Salpingitis isthmica nodosa is strongly associated with infertility and ectopic pregnancy.
- Micro: The isthmic/proximal segment of the tube shows variably sized, dilated glandular structures lined by ciliated, columnar epithelium, surrounded by hypertrophic muscle.
- Ancillary: No specific ancillary studies are clinically relevant for the diagnosis of Salpingitis isthmica nodosa.
Reference Gallery:
Salpingitis isthmica nodosa. A central dilated lumen with surrounding gland-like structures and hypertrophic smooth muscle.

Q: In a Tubo-ovarian Abscess, the characteristic gross and radiographic finding is an adnexal mass containing a large, destructive [...] involving the fallopian tube and ovary.
Tubo-ovarian abscess. The mass contains a large abscess cavity.
A: abscess cavity
Back Extra: Tubo-ovarian Abscess
- Clinical: Tubo-ovarian abscess typically presents with an adnexal mass, fever, lower abdominal or pelvic pain, vaginal discharge, and leukocytosis.
- Micro: Histologically, there is destructive acute and chronic inflammation, necrosis, abscess formation, and fibrosis involving the fallopian tube and ovary.
- Ancillary: Imaging studies often show an abscess cavity within the adnexal mass, which is a key diagnostic feature.
Reference Gallery:
Tubo-ovarian abscess. The mass contains a large abscess cavity.

Q: A rare, benign finding in the fallopian tubes of postpartum women characterized by a microscopic, intraluminal, papillary proliferation with abundant eosinophilic cytoplasm and minimal atypia is a [...].
Metaplastic papillary lesion. Low-power view of microscopic, intraluminal, papillary proliferation with minimal budding.
Metaplastic papillary lesion. The proliferation has a hierarchical pattern and is lined by columnar cells with abundant eosinophilic cytoplasm.
A: metaplastic papillary lesion
Back Extra: Metaplastic Papillary Lesion
- Clinical: Metaplastic papillary lesion is typically seen in the fallopian tubes of postpartum women and is a rare condition (case reports only).
- Micro: Characterized by a microscopic, intraluminal, papillary proliferation with columnar cells having abundant eosinophilic cytoplasm and minimal nuclear atypia.
- Ancillary: Microsatellite analysis shows a low fractional allelic imbalance rate index, and there is loss of PTEN expression and cytoplasmic WT1 immunoreactivity in some cases.
Reference Gallery:
Metaplastic papillary lesion. Low-power view of microscopic, intraluminal, papillary proliferation with minimal budding.
Metaplastic papillary lesion. The proliferation has a hierarchical pattern and is lined by columnar cells with abundant eosinophilic cytoplasm.

Q: A metaplastic papillary lesion of the fallopian tube typically features a hierarchical, intraluminal papillary proliferation lined by columnar cells with abundant [...] cytoplasm.
Metaplastic papillary lesion. The proliferation has a hierarchical pattern and is lined by columnar cells with abundant eosinophilic cytoplasm.
A: eosinophilic
Back Extra: Metaplastic Papillary Lesion
- Clinical: Metaplastic papillary lesion is typically seen in the fallopian tubes of postpartum women and is a rare condition (case reports only).
- Micro: Characterized by a microscopic, intraluminal, papillary proliferation with columnar cells having abundant eosinophilic cytoplasm and minimal nuclear atypia.
- Ancillary: Microsatellite analysis shows a low fractional allelic imbalance rate index, and there is loss of PTEN expression and cytoplasmic WT1 immunoreactivity in some cases.
Reference Gallery:
Metaplastic papillary lesion. Low-power view of microscopic, intraluminal, papillary proliferation with minimal budding.
Metaplastic papillary lesion. The proliferation has a hierarchical pattern and is lined by columnar cells with abundant eosinophilic cytoplasm.

Q: Histologically, coarse papillary excrescences projecting into a cystic space with marked stromal edema and no significant epithelial proliferation are characteristic of the adenofibromatous component of [...].
Serous adenofibroma. Coarse papillary excrescences project into a cystic space.
Serous adenofibroma. Papillary pattern without epithelial proliferation and marked stromal oedema.
A: Serous Adenofibroma and Papilloma of the Fallopian Tube
Serous Adenofibroma and Papilloma of the Fallopian Tube
- Clinical: Most women with Serous Adenofibroma and Papilloma of the Fallopian Tube are asymptomatic, and these tumours are often discovered incidentally during surgery for other gynaecological disorders.
- Micro: Serous Adenofibromas have admixed epithelial and mesenchymal components and may be cystic. Papillomas are typically composed of delicate, branching fibrovascular stalks lined by bland, non-ciliated epithelium.
- Ancillary: Ancillary studies for Serous Adenofibroma and Papilloma of the Fallopian Tube are not clinically relevant.
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Serous adenofibroma. Coarse papillary excrescences project into a cystic space.
Serous adenofibroma. Papillary pattern without epithelial proliferation and marked stromal oedema.
Fallopian tube papilloma. Branching papillary architecture with a normal thickness lining epithelium.

Q: A delicate, branching papillary architecture supported by fibrovascular stalks and lined by a bland, normal-thickness epithelium is the hallmark microscopic finding in the papilloma component of [...].
Fallopian tube papilloma. Branching papillary architecture with a normal thickness lining epithelium.
A: Serous Adenofibroma and Papilloma of the Fallopian Tube
Serous Adenofibroma and Papilloma of the Fallopian Tube
- Clinical: Most women with Serous Adenofibroma and Papilloma of the Fallopian Tube are asymptomatic, and these tumours are often discovered incidentally during surgery for other gynaecological disorders.
- Micro: Serous Adenofibromas have admixed epithelial and mesenchymal components and may be cystic. Papillomas are typically composed of delicate, branching fibrovascular stalks lined by bland, non-ciliated epithelium.
- Ancillary: Ancillary studies for Serous Adenofibroma and Papilloma of the Fallopian Tube are not clinically relevant.
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Serous adenofibroma. Coarse papillary excrescences project into a cystic space.
Serous adenofibroma. Papillary pattern without epithelial proliferation and marked stromal oedema.
Fallopian tube papilloma. Branching papillary architecture with a normal thickness lining epithelium.

Q: Microscopically, a Serous Borderline Tumor typically demonstrates [...] of papillae along with detached cell clusters.
Serous borderline tumour. Hierarchical branching of papillae with detached cell clusters.
A: hierarchical branching
Back Extra: Serous Borderline Tumour
- Clinical: Patients with serous borderline tumours typically present with abdominal pain and are usually in their 40s.
- Micro: Serous borderline tumours of the fallopian tube show hierarchical branching of papillae with detached cell clusters and low-grade proliferative activity.
- Ancillary: Ancillary studies are not clinically relevant for diagnosing serous borderline tumours.
Reference Gallery:
Serous borderline tumour. Hierarchical branching of papillae with detached cell clusters.
Serous borderline tumour. Low-grade proliferative activity with budding and tufting.

Q: Histologically, the low-grade proliferative activity of a Serous Borderline Tumor is often characterized by epithelial [...].
Serous borderline tumour. Low-grade proliferative activity with budding and tufting.
A: budding and tufting
Back Extra: Serous Borderline Tumour
- Clinical: Patients with serous borderline tumours typically present with abdominal pain and are usually in their 40s.
- Micro: Serous borderline tumours of the fallopian tube show hierarchical branching of papillae with detached cell clusters and low-grade proliferative activity.
- Ancillary: Ancillary studies are not clinically relevant for diagnosing serous borderline tumours.
Reference Gallery:
Serous borderline tumour. Hierarchical branching of papillae with detached cell clusters.
Serous borderline tumour. Low-grade proliferative activity with budding and tufting.

Q: Histologically, Endometrioid Adenocarcinoma of the Fallopian Tube typically resembles its uterine counterpart, with low-grade tumors characteristically demonstrating an architecture composed of [...].
Endometrioid carcinoma. Grade 1 endometrioid adenocarcinoma, composed of closely packed glands, arising in the wall of the fallopian tube.
A: closely packed glands
Back Extra: Endometrioid Adenocarcinoma of the Fallopian Tube
- Clinical: Endometrioid carcinoma of the fallopian tube can present with a pelvic mass or abdominal pain, or as an incidental finding in the distal two-thirds of the tube.
- Micro: Morphology is similar to endometrial endometrioid carcinomas, often showing areas of solid growth, spindled cells, and small glands.
- Ancillary: Immunohistochemistry (IHC) shows WT1 negativity and p53 wildtype.
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Endometrioid carcinoma. Grade 1 endometrioid adenocarcinoma, composed of closely packed glands, arising in the wall of the fallopian tube.

Q: The defining non-invasive precursor lesion to High-grade Serous Carcinoma of the Fallopian Tube is [...] (STIC).
Carcinoma of the tube with serous tubal intraepithelial carcinoma. Serous tubal intraepithelial carcinoma (left) merging with early invasive serous carcinoma in the fimbria.
A: serous tubal intraepithelial carcinoma
Back Extra: High-grade Serous Carcinoma of the Fallopian Tube
- Clinical: High-grade serous carcinoma of the fallopian tube typically presents with a sausage-like adnexal mass and can be associated with the rare triad of hydrops tubae profluens (pain, watery discharge, and pelvic mass).
- Micro: High-grade serous carcinoma of the fallopian tube shows characteristic poorly formed glands, slit-forming spaces, and high nuclear grade. Serous tubal intraepithelial carcinoma (STIC) is a non-invasive subtype and is characterized by abnormal morphological features such as high N:C ratio, nuclear enlargement, and lack of ciliated cells.
- Ancillary: High-grade serous carcinoma of the fallopian tube often demonstrates a deleterious TP53 mutation, which is reflected in aberrant p53 expression (diffuse or nearly diffuse nuclear staining or complete loss of nuclear staining).
Reference Gallery:
Serous tubal intraepithelial lesion. Pseudostratified growth of columnar cells with increased N:C ratio, mild nuclear pleomorphism, and preserved cell polarity.
Serous tubal intraepithelial lesion. The lesion shown in Fig. 10543 stains strongly for p53.
High-grade serous carcinoma. A single focus of high-grade serous carcinoma on the ovarian surface adjacent to the tube with the lesion illustrated in the tube in Fig. 10543 and Fig. 10544. In this scenario, the extratubal malignancy develops after the escape of cells from early serous precursors (serous tubal intraepithelial lesion) from the tube. This is distinct from cancers that arise in the tube per se.
Carcinoma of the tube with serous tubal intraepithelial carcinoma. Serous tubal intraepithelial carcinoma (left) merging with early invasive serous carcinoma in the fimbria.
High-grade serous carcinoma. Microscopic image of high-grade serous carcinoma of the tube, with the characteristic poorly formed glands, slit-forming spaces, and high nuclear grade.

Q: Histologically, High-grade Serous Carcinoma of the Fallopian Tube classically exhibits high nuclear grade, poorly formed glands, and characteristic [...].
High-grade serous carcinoma. Microscopic image of high-grade serous carcinoma of the tube, with the characteristic poorly formed glands, slit-forming spaces, and high nuclear grade.
A: slit-forming spaces
Back Extra: High-grade Serous Carcinoma of the Fallopian Tube
- Clinical: High-grade serous carcinoma of the fallopian tube typically presents with a sausage-like adnexal mass and can be associated with the rare triad of hydrops tubae profluens (pain, watery discharge, and pelvic mass).
- Micro: High-grade serous carcinoma of the fallopian tube shows characteristic poorly formed glands, slit-forming spaces, and high nuclear grade. Serous tubal intraepithelial carcinoma (STIC) is a non-invasive subtype and is characterized by abnormal morphological features such as high N:C ratio, nuclear enlargement, and lack of ciliated cells.
- Ancillary: High-grade serous carcinoma of the fallopian tube often demonstrates a deleterious TP53 mutation, which is reflected in aberrant p53 expression (diffuse or nearly diffuse nuclear staining or complete loss of nuclear staining).
Reference Gallery:
Serous tubal intraepithelial lesion. Pseudostratified growth of columnar cells with increased N:C ratio, mild nuclear pleomorphism, and preserved cell polarity.
Serous tubal intraepithelial lesion. The lesion shown in Fig. 10543 stains strongly for p53.
High-grade serous carcinoma. A single focus of high-grade serous carcinoma on the ovarian surface adjacent to the tube with the lesion illustrated in the tube in Fig. 10543 and Fig. 10544. In this scenario, the extratubal malignancy develops after the escape of cells from early serous precursors (serous tubal intraepithelial lesion) from the tube. This is distinct from cancers that arise in the tube per se.
Carcinoma of the tube with serous tubal intraepithelial carcinoma. Serous tubal intraepithelial carcinoma (left) merging with early invasive serous carcinoma in the fimbria.
High-grade serous carcinoma. Microscopic image of high-grade serous carcinoma of the tube, with the characteristic poorly formed glands, slit-forming spaces, and high nuclear grade.

Q: Driven by a deleterious mutation, High-grade Serous Carcinoma of the Fallopian Tube and its precursors characteristically show aberrant expression (e.g., diffuse strong nuclear staining or a null pattern) of [...] on immunohistochemistry.
Serous tubal intraepithelial lesion. The lesion shown in Fig. 10543 stains strongly for p53.
A: p53
Back Extra: High-grade Serous Carcinoma of the Fallopian Tube
- Clinical: High-grade serous carcinoma of the fallopian tube typically presents with a sausage-like adnexal mass and can be associated with the rare triad of hydrops tubae profluens (pain, watery discharge, and pelvic mass).
- Micro: High-grade serous carcinoma of the fallopian tube shows characteristic poorly formed glands, slit-forming spaces, and high nuclear grade. Serous tubal intraepithelial carcinoma (STIC) is a non-invasive subtype and is characterized by abnormal morphological features such as high N:C ratio, nuclear enlargement, and lack of ciliated cells.
- Ancillary: High-grade serous carcinoma of the fallopian tube often demonstrates a deleterious TP53 mutation, which is reflected in aberrant p53 expression (diffuse or nearly diffuse nuclear staining or complete loss of nuclear staining).
Reference Gallery:
Serous tubal intraepithelial lesion. Pseudostratified growth of columnar cells with increased N:C ratio, mild nuclear pleomorphism, and preserved cell polarity.
Serous tubal intraepithelial lesion. The lesion shown in Fig. 10543 stains strongly for p53.
High-grade serous carcinoma. A single focus of high-grade serous carcinoma on the ovarian surface adjacent to the tube with the lesion illustrated in the tube in Fig. 10543 and Fig. 10544. In this scenario, the extratubal malignancy develops after the escape of cells from early serous precursors (serous tubal intraepithelial lesion) from the tube. This is distinct from cancers that arise in the tube per se.
Carcinoma of the tube with serous tubal intraepithelial carcinoma. Serous tubal intraepithelial carcinoma (left) merging with early invasive serous carcinoma in the fimbria.
High-grade serous carcinoma. Microscopic image of high-grade serous carcinoma of the tube, with the characteristic poorly formed glands, slit-forming spaces, and high nuclear grade.

Q: An adnexal tumor exhibiting an admixture of hollow to solid tubules, sieve-like cysts, and diffuse spindled growth within a prominently hyalinized stroma is the [...].
Wolffian tumour. The tumour shows a solid growth and spindled cells.
Wolffian tumour. There are solid and hollow tubules in a hyalinized stroma.
A: Wolffian Tumour
Back Extra: Wolffian Tumour
- Clinical: Patients range in age from 19 to 83 years (mean: 45 years) and may present with abdominopelvic pain or abnormal bleeding; however, many cases are incidental findings.
- Micro: The tumours are composed of an admixture of hollow to solid tubules, sieve-like cysts, and diffuse (sometimes spindled) growth. Hyalinized bands may be prominent or delicate.
- Ancillary: Most are positive for broad-spectrum keratins, CK7, vimentin, CD10, inhibin, and calretinin, with variable expression of hormone receptors and SF1.
Reference Gallery:
Wolffian tumour. The tumour shows a solid growth and spindled cells.
Wolffian tumour. There are solid and hollow tubules in a hyalinized stroma.
Wolffian tumour. The tumour shows a solid tubular growth and uniform nuclei lacking overt atypia, nucleoli, and mitoses.

Q: On high-power examination, the neoplastic cells of a Wolffian Tumour exhibit uniform nuclei that are classically devoid of prominent nucleoli, frequent mitoses, and overt [...].
Wolffian tumour. The tumour shows a solid tubular growth and uniform nuclei lacking overt atypia, nucleoli, and mitoses.
A: atypia
Back Extra: Wolffian Tumour
- Clinical: Patients range in age from 19 to 83 years (mean: 45 years) and may present with abdominopelvic pain or abnormal bleeding; however, many cases are incidental findings.
- Micro: The tumours are composed of an admixture of hollow to solid tubules, sieve-like cysts, and diffuse (sometimes spindled) growth. Hyalinized bands may be prominent or delicate.
- Ancillary: Most are positive for broad-spectrum keratins, CK7, vimentin, CD10, inhibin, and calretinin, with variable expression of hormone receptors and SF1.
Reference Gallery:
Wolffian tumour. The tumour shows a solid growth and spindled cells.
Wolffian tumour. There are solid and hollow tubules in a hyalinized stroma.
Wolffian tumour. The tumour shows a solid tubular growth and uniform nuclei lacking overt atypia, nucleoli, and mitoses.

Q: Mucinous metaplasia of the fallopian tube is microscopically characterized by the partial replacement of the normal epithelial lining by a [...].
Mucinous metaplasia. Fallopian tube mucosa with replacement of normal epithelial lining cells by mucinous cells.
A: monolayer of bland mucinous cells
Back Extra: Mucinous Metaplasia
- Clinical: Mucinous metaplasia is mostly an incidental finding and can be associated with gynaecological neoplasia.
- Micro: The tubal lining is partly replaced by a monolayer of bland mucinous cells, and chronic inflammation and other metaplasias may be present.
- Ancillary: Immunohistochemical markers such as CK7 and CK20 can help distinguish between primary metaplasia and metastatic disease.
Reference Gallery:
Mucinous metaplasia. Fallopian tube mucosa with replacement of normal epithelial lining cells by mucinous cells.

Q: Microscopically, the cyst lining of a Follicle Cyst characteristically consists of an inner layer of eosinophilic, luteinized [...] and an outer layer of theca cells.
Follicle cyst. The cyst lining consists of eosinophilic luteinized granulosa cells and an outer layer of theca cells.
A: granulosa cells
Back Extra: Follicle Cyst
- Clinical: Follicle cysts are most often asymptomatic but may present with pelvic pain due to rupture or torsion. They are most common in women of reproductive age.
- Micro: The cyst lining consists of a variable number of layers of granulosa cells, which may be luteinized, and an outer layer of luteinized theca cells.
- Ancillary: Ancillary studies are not typically required for diagnosis.
Reference Gallery:
Follicle cyst. The cyst lining consists of eosinophilic luteinized granulosa cells and an outer layer of theca cells.

Q: In a Follicle Cyst, the characteristic biphasic lining consists of inner granulosa cells surrounded by an outer layer of luteinized [...].
Follicle cyst. The cyst lining consists of eosinophilic luteinized granulosa cells and an outer layer of theca cells.
A: theca cells
Back Extra: Follicle Cyst
- Clinical: Follicle cysts are most often asymptomatic but may present with pelvic pain due to rupture or torsion. They are most common in women of reproductive age.
- Micro: The cyst lining consists of a variable number of layers of granulosa cells, which may be luteinized, and an outer layer of luteinized theca cells.
- Ancillary: Ancillary studies are not typically required for diagnosis.
Reference Gallery:
Follicle cyst. The cyst lining consists of eosinophilic luteinized granulosa cells and an outer layer of theca cells.

Q: Microscopically, the undulating thick lining of a Corpus Luteum Cyst is primarily composed of large [...] cells with abundant eosinophilic cytoplasm.
Corpus luteum cyst. The cyst is lined by a thick layer of luteinized granulosa cells with abundant eosinophilic cytoplasm.
A: luteinized granulosa
Q: Corpus Luteum Cyst
- Clinical: Most patients with a [...] are asymptomatic, but it may present with irregular menstruation, abdominal pain, or haemoperitoneum due to rupture.
- Micro: [...] have an undulating thick lining composed of large luteinized granulosa cells with uniform small nuclei and abundant large eosinophilic cytoplasm.
- Ancillary: [...] usually resolve spontaneously.
Reference Gallery:
Corpus luteum cyst. The cyst is lined by a thick layer of luteinized granulosa cells with abundant eosinophilic cytoplasm.
A: corpus luteum cyst; Corpus luteum cysts; Corpus luteum cysts

Q: An ovarian cyst demonstrating a thick, undulating lining of cells with uniform small nuclei and abundant eosinophilic cytoplasm is characteristic of a [...].
Corpus luteum cyst. The cyst is lined by a thick layer of luteinized granulosa cells with abundant eosinophilic cytoplasm.
A: Corpus Luteum Cyst
Q: Corpus Luteum Cyst
- Clinical: Most patients with a [...] are asymptomatic, but it may present with irregular menstruation, abdominal pain, or haemoperitoneum due to rupture.
- Micro: [...] have an undulating thick lining composed of large luteinized granulosa cells with uniform small nuclei and abundant large eosinophilic cytoplasm.
- Ancillary: [...] usually resolve spontaneously.
Reference Gallery:
Corpus luteum cyst. The cyst is lined by a thick layer of luteinized granulosa cells with abundant eosinophilic cytoplasm.
A: corpus luteum cyst; Corpus luteum cysts; Corpus luteum cysts

Q: A large solitary luteinized follicle cyst is typically discovered incidentally during [...], cesarean section, or the puerperium.
Large solitary luteinized follicle cyst. The cyst was removed at 19 weeks of gestational age. Low magnification shows a thin cyst wall lined by luteinized granulosa cells.
A: pregnancy
Back Extra: Large Solitary Luteinized Follicle Cyst
- Clinical: The cyst is usually discovered incidentally during pregnancy, caesarean section, or puerperium and may present with abdominal discomfort or pain.
- Micro: The cyst lining consists of one to several luteinized granulosa cell layers with small, uniform, round nuclei and abundant eosinophilic cytoplasm.
- Ancillary: Cyst fluid aspirate shows moderate cellularity, with monolayers of uniform luteinized granulosa cells showing occasional nuclear enlargement and hyperchromasia.
Reference Gallery:
Large solitary luteinized follicle cyst. The cyst was removed at 19 weeks of gestational age. Low magnification shows a thin cyst wall lined by luteinized granulosa cells.
Large solitary luteinized follicle cyst. High magnification shows luteinized granulosa cells with round nuclei and abundant eosinophilic cytoplasm. Focal nuclear enlargement may be seen.

Q: The characteristic microscopic finding in a large solitary luteinized follicle cyst is a thin cyst wall lined by one to several layers of [...] with abundant eosinophilic cytoplasm.
Large solitary luteinized follicle cyst. The cyst was removed at 19 weeks of gestational age. Low magnification shows a thin cyst wall lined by luteinized granulosa cells.
Large solitary luteinized follicle cyst. High magnification shows luteinized granulosa cells with round nuclei and abundant eosinophilic cytoplasm. Focal nuclear enlargement may be seen.
A: luteinized granulosa cells
Back Extra: Large Solitary Luteinized Follicle Cyst
- Clinical: The cyst is usually discovered incidentally during pregnancy, caesarean section, or puerperium and may present with abdominal discomfort or pain.
- Micro: The cyst lining consists of one to several luteinized granulosa cell layers with small, uniform, round nuclei and abundant eosinophilic cytoplasm.
- Ancillary: Cyst fluid aspirate shows moderate cellularity, with monolayers of uniform luteinized granulosa cells showing occasional nuclear enlargement and hyperchromasia.
Reference Gallery:
Large solitary luteinized follicle cyst. The cyst was removed at 19 weeks of gestational age. Low magnification shows a thin cyst wall lined by luteinized granulosa cells.
Large solitary luteinized follicle cyst. High magnification shows luteinized granulosa cells with round nuclei and abundant eosinophilic cytoplasm. Focal nuclear enlargement may be seen.

Q: While the lining of a large solitary luteinized follicle cyst generally features uniform, round nuclei, high-power examination frequently reveals focal [...] and hyperchromasia.
Large solitary luteinized follicle cyst. High magnification shows luteinized granulosa cells with round nuclei and abundant eosinophilic cytoplasm. Focal nuclear enlargement may be seen.
A: nuclear enlargement
Back Extra: Large Solitary Luteinized Follicle Cyst
- Clinical: The cyst is usually discovered incidentally during pregnancy, caesarean section, or puerperium and may present with abdominal discomfort or pain.
- Micro: The cyst lining consists of one to several luteinized granulosa cell layers with small, uniform, round nuclei and abundant eosinophilic cytoplasm.
- Ancillary: Cyst fluid aspirate shows moderate cellularity, with monolayers of uniform luteinized granulosa cells showing occasional nuclear enlargement and hyperchromasia.
Reference Gallery:
Large solitary luteinized follicle cyst. The cyst was removed at 19 weeks of gestational age. Low magnification shows a thin cyst wall lined by luteinized granulosa cells.
Large solitary luteinized follicle cyst. High magnification shows luteinized granulosa cells with round nuclei and abundant eosinophilic cytoplasm. Focal nuclear enlargement may be seen.

Q: A hallmark histologic and macroscopic finding in complete Ovarian Dysgenesis is the presence of bilateral [...], which are composed almost exclusively of ovarian-type stroma that may contain primitive cord-like structures.
Gonadal dysgenesis. Trabeculae or cord-like structures consisting only of sex cord–like cells or an intimate mixture of primitive germ cells and sex cord–like cells mimicking features of gonadoblastoma in the ovarian-type stroma.
A: streak gonads
Back Extra: Ovarian Dysgenesis
- Clinical: Individuals with complete gonadal dysgenesis (CGD) usually present with primary amenorrhoea and absence of secondary sexual characteristics, while those with partial gonadal dysgenesis (PGD) often present with ambiguous genitalia at birth.
- Micro: Bilateral streak gonads in CGD are almost exclusively composed of ovarian-type stroma, while PGD shows a mixture of developed testicular tissue and streak gonads with histological features like trabeculae or cord-like structures.
- Ancillary: Genetic testing is crucial for confirming the diagnosis and identifying the risk of gonadoblastoma and germ cell tumors.
Reference Gallery:
Gonadal dysgenesis. Trabeculae or cord-like structures consisting only of sex cord–like cells or an intimate mixture of primitive germ cells and sex cord–like cells mimicking features of gonadoblastoma in the ovarian-type stroma.

Q: In partial Ovarian Dysgenesis, the dysgenetic tissue can show trabeculae or cord-like structures containing an intimate mixture of primitive germ cells and sex cord–like cells, histologically mimicking a [...].
Gonadal dysgenesis. Trabeculae or cord-like structures consisting only of sex cord–like cells or an intimate mixture of primitive germ cells and sex cord–like cells mimicking features of gonadoblastoma in the ovarian-type stroma.
A: gonadoblastoma
Back Extra: Ovarian Dysgenesis
- Clinical: Individuals with complete gonadal dysgenesis (CGD) usually present with primary amenorrhoea and absence of secondary sexual characteristics, while those with partial gonadal dysgenesis (PGD) often present with ambiguous genitalia at birth.
- Micro: Bilateral streak gonads in CGD are almost exclusively composed of ovarian-type stroma, while PGD shows a mixture of developed testicular tissue and streak gonads with histological features like trabeculae or cord-like structures.
- Ancillary: Genetic testing is crucial for confirming the diagnosis and identifying the risk of gonadoblastoma and germ cell tumors.
Reference Gallery:
Gonadal dysgenesis. Trabeculae or cord-like structures consisting only of sex cord–like cells or an intimate mixture of primitive germ cells and sex cord–like cells mimicking features of gonadoblastoma in the ovarian-type stroma.

Q: Microscopic examination of Hyperreactio luteinalis reveals ovaries with multiple cystic follicles lined by [...] granulosa and theca interna cells set within an edematous stroma.
Hyperreactio luteinalis. Multiple luteinized cystic follicles are characteristic.
A: luteinized
Back Extra: Hyperreactio luteinalis
- Clinical: Hyperreactio luteinalis occurs during the second or third trimester of pregnancy and may cause abdominal pain due to ovarian torsion or rupture.
- Micro: Histopathology reveals ovaries with multiple cystic follicles lined by luteinized granulosa and theca interna cells in an oedematous stroma.
- Ancillary: There are no clinically relevant ancillary studies for this condition.
Reference Gallery:
Hyperreactio luteinalis. Multiple luteinized cystic follicles are characteristic.
Hyperreactio luteinalis. An ultrasound image shows multiple ovarian cysts at 10 weeks of gestation.

Q: Hyperreactio luteinalis typically occurs during pregnancy and classically presents on ultrasound as enlarged ovaries containing multiple [...], which may cause abdominal pain due to torsion or rupture.
Hyperreactio luteinalis. An ultrasound image shows multiple ovarian cysts at 10 weeks of gestation.
A: cysts
Back Extra: Hyperreactio luteinalis
- Clinical: Hyperreactio luteinalis occurs during the second or third trimester of pregnancy and may cause abdominal pain due to ovarian torsion or rupture.
- Micro: Histopathology reveals ovaries with multiple cystic follicles lined by luteinized granulosa and theca interna cells in an oedematous stroma.
- Ancillary: There are no clinically relevant ancillary studies for this condition.
Reference Gallery:
Hyperreactio luteinalis. Multiple luteinized cystic follicles are characteristic.
Hyperreactio luteinalis. An ultrasound image shows multiple ovarian cysts at 10 weeks of gestation.

Q: Histopathologically, a [...] presents as a multinodular proliferation of luteinized cells with round, uniform nuclei, visible nucleoli, and characteristic follicle-like spaces containing eosinophilic secretions.
Pregnancy luteoma. Note the proliferation of large eosinophilic cells with several follicle-like spaces.
Pregnancy luteoma. Note the luteal cells with round uniform nuclei with visible nucleoli and rare mitotic figures.
A: Pregnancy Luteoma
Back Extra: Pregnancy Luteoma
- Clinical: Pregnancy luteoma is usually an incidental finding near term, during caesarean section, or immediately postpartum in patients 15–44 years of age. Rare androgenic manifestations—maternal and/or fetal—have been reported.
- Micro: Histopathology reveals a multinodular proliferation of luteinized cells with round nuclei and abundant eosinophilic cytoplasm. Follicle-like spaces are common and may contain eosinophilic secretions.
- Ancillary: These are benign lesions that usually regress spontaneously postpartum.
Reference Gallery:
Pregnancy luteoma. Note the proliferation of large eosinophilic cells with several follicle-like spaces.
Pregnancy luteoma. Note the luteal cells with round uniform nuclei with visible nucleoli and rare mitotic figures.

Q: In a Pregnancy Luteoma, the characteristic luteinized cells have abundant eosinophilic cytoplasm and frequently arrange into distinct [...].
Pregnancy luteoma. Note the proliferation of large eosinophilic cells with several follicle-like spaces.
A: follicle-like spaces
Back Extra: Pregnancy Luteoma
- Clinical: Pregnancy luteoma is usually an incidental finding near term, during caesarean section, or immediately postpartum in patients 15–44 years of age. Rare androgenic manifestations—maternal and/or fetal—have been reported.
- Micro: Histopathology reveals a multinodular proliferation of luteinized cells with round nuclei and abundant eosinophilic cytoplasm. Follicle-like spaces are common and may contain eosinophilic secretions.
- Ancillary: These are benign lesions that usually regress spontaneously postpartum.
Reference Gallery:
Pregnancy luteoma. Note the proliferation of large eosinophilic cells with several follicle-like spaces.
Pregnancy luteoma. Note the luteal cells with round uniform nuclei with visible nucleoli and rare mitotic figures.

Q: In Leydig Cell Hyperplasia, histologic examination reveals nodules of polygonal cells in the ovarian hilus that often encircle nerve fibers and may contain characteristic intracytoplasmic inclusions known as [...].
Leydig cell hyperplasia. Note the nodular proliferation of Leydig cells encircling nerve fibres in the hilar region of the ovary. Lipofuscin pigment and rare Reinke crystals are seen.
A: Reinke crystals
Back Extra: Leydig Cell Hyperplasia
- Clinical: Androgenic and estrogenic manifestations are possible. This lesion is most commonly seen in pregnant, perimenopausal, and postmenopausal women.
- Micro: Histopathology reveals nodules of Leydig cells within the ovarian hilus that may encircle nerve fibres and rete ovarii. The cells are typically polygonal with central round nuclei and abundant eosinophilic cytoplasm, which may contain Reinke crystals.
- Ancillary: Ancillary studies are not clinically relevant for this condition.
Reference Gallery:
Leydig cell hyperplasia. Note the nodular proliferation of Leydig cells encircling nerve fibres in the hilar region of the ovary. Lipofuscin pigment and rare Reinke crystals are seen.

Q: Histologic sections showing a nodular proliferation of polygonal cells with abundant eosinophilic cytoplasm, lipofuscin pigment, and Reinke crystals that characteristically encircle nerve fibers in the ovarian hilus is diagnostic of [...].
Leydig cell hyperplasia. Note the nodular proliferation of Leydig cells encircling nerve fibres in the hilar region of the ovary. Lipofuscin pigment and rare Reinke crystals are seen.
A: Leydig Cell Hyperplasia
Back Extra: Leydig Cell Hyperplasia
- Clinical: Androgenic and estrogenic manifestations are possible. This lesion is most commonly seen in pregnant, perimenopausal, and postmenopausal women.
- Micro: Histopathology reveals nodules of Leydig cells within the ovarian hilus that may encircle nerve fibres and rete ovarii. The cells are typically polygonal with central round nuclei and abundant eosinophilic cytoplasm, which may contain Reinke crystals.
- Ancillary: Ancillary studies are not clinically relevant for this condition.
Reference Gallery:
Leydig cell hyperplasia. Note the nodular proliferation of Leydig cells encircling nerve fibres in the hilar region of the ovary. Lipofuscin pigment and rare Reinke crystals are seen.

Q: [...] is a bilateral ovarian proliferation characterized microscopically by densely cellular spindle areas abruptly transitioning to marked edema with scattered luteinized cells.
Luteinized thecoma associated with sclerosing peritonitis. A densely cellular area (top left) transitions abruptly to an area of marked oedema (bottom right). Nests of weakly luteinized cells are more apparent in the oedematous area but are present throughout the image.
A: Luteinized Thecoma Associated with Sclerosing Peritonitis
Back Extra: Luteinized Thecoma Associated with Sclerosing Peritonitis
- Clinical: Luteinized thecoma associated with sclerosing peritonitis is typically bilateral, presenting with abdominal swelling, ascites, and symptoms of bowel obstruction, often due to underlying sclerosing peritonitis.
- Micro: The ovaries show hypercellularity with scattered zones of oedema, spindle cells with brisk mitotic activity, and luteinized or weakly luteinized cells.
- Ancillary: Immunohistochemically, spindle cells are positive for SF1 and FOXL2 but negative for inhibin and calretinin, while luteinized cells are positive for inhibin and calretinin.
Reference Gallery:
Luteinized thecoma associated with sclerosing peritonitis. A densely cellular area (top left) transitions abruptly to an area of marked oedema (bottom right). Nests of weakly luteinized cells are more apparent in the oedematous area but are present throughout the image.

Q: In Luteinized Thecoma Associated with Sclerosing Peritonitis, a characteristic microscopic feature is the abrupt transition from densely cellular spindle cell zones to areas of marked [...] containing nests of weakly luteinized cells.
Luteinized thecoma associated with sclerosing peritonitis. A densely cellular area (top left) transitions abruptly to an area of marked oedema (bottom right). Nests of weakly luteinized cells are more apparent in the oedematous area but are present throughout the image.
A: edema
Back Extra: Luteinized Thecoma Associated with Sclerosing Peritonitis
- Clinical: Luteinized thecoma associated with sclerosing peritonitis is typically bilateral, presenting with abdominal swelling, ascites, and symptoms of bowel obstruction, often due to underlying sclerosing peritonitis.
- Micro: The ovaries show hypercellularity with scattered zones of oedema, spindle cells with brisk mitotic activity, and luteinized or weakly luteinized cells.
- Ancillary: Immunohistochemically, spindle cells are positive for SF1 and FOXL2 but negative for inhibin and calretinin, while luteinized cells are positive for inhibin and calretinin.
Reference Gallery:
Luteinized thecoma associated with sclerosing peritonitis. A densely cellular area (top left) transitions abruptly to an area of marked oedema (bottom right). Nests of weakly luteinized cells are more apparent in the oedematous area but are present throughout the image.

Q: Histologically, a Brenner tumor is characterized by small nests of bland [...] (or urothelial) epithelium embedded within a dense stroma.
Brenner tumour. Small nests and cysts in a fibromatous background.
Brenner tumour. Transitional/urothelial nests (some of which show cyst formation) are in a fibromatous stroma.
A: transitional
Back Extra: Brenner Tumor
- Clinical: Brenner tumors are usually unilateral ovarian tumors, often found incidentally, and are typically asymptomatic.
- Micro: The tumor is composed of small nests of bland transitional/urothelial epithelium in a dense fibromatous stroma, with occasional microcystic spaces.
- Ancillary: Brenner tumors express GATA3, CK7, p63, S100P, AR, uroplakin, and thrombomodulin, and do not express (or only focally express) CK20.
Reference Gallery:
Brenner tumour. Small nests and cysts in a fibromatous background.
Brenner tumour. Transitional/urothelial nests (some of which show cyst formation) are in a fibromatous stroma.
Brenner tumour. Characteristic cytological features include uniform oval cells with pale cytoplasm, nuclei with occasional grooves, fine chromatin, and small nucleoli.
Benign Brenner tumour. A small, predominantly fibromatous tumour with scattered nests of bland transitional epithelium.
Benign Brenner tumour. Nests of bland transitional epithelium surrounded by dense fibromatous tissue.

Q: On high-power examination of a Brenner tumor, the epithelial cells typically possess uniform oval nuclei that display characteristic longitudinal [...].
Brenner tumour. Characteristic cytological features include uniform oval cells with pale cytoplasm, nuclei with occasional grooves, fine chromatin, and small nucleoli.
A: grooves
Back Extra: Brenner Tumor
- Clinical: Brenner tumors are usually unilateral ovarian tumors, often found incidentally, and are typically asymptomatic.
- Micro: The tumor is composed of small nests of bland transitional/urothelial epithelium in a dense fibromatous stroma, with occasional microcystic spaces.
- Ancillary: Brenner tumors express GATA3, CK7, p63, S100P, AR, uroplakin, and thrombomodulin, and do not express (or only focally express) CK20.
Reference Gallery:
Brenner tumour. Small nests and cysts in a fibromatous background.
Brenner tumour. Transitional/urothelial nests (some of which show cyst formation) are in a fibromatous stroma.
Brenner tumour. Characteristic cytological features include uniform oval cells with pale cytoplasm, nuclei with occasional grooves, fine chromatin, and small nucleoli.
Benign Brenner tumour. A small, predominantly fibromatous tumour with scattered nests of bland transitional epithelium.
Benign Brenner tumour. Nests of bland transitional epithelium surrounded by dense fibromatous tissue.

Q: The distinctive transitional epithelial nests in a Brenner tumor are characteristically surrounded by a dense, [...] stroma.
Benign Brenner tumour. A small, predominantly fibromatous tumour with scattered nests of bland transitional epithelium.
Benign Brenner tumour. Nests of bland transitional epithelium surrounded by dense fibromatous tissue.
A: fibromatous
Back Extra: Brenner Tumor
- Clinical: Brenner tumors are usually unilateral ovarian tumors, often found incidentally, and are typically asymptomatic.
- Micro: The tumor is composed of small nests of bland transitional/urothelial epithelium in a dense fibromatous stroma, with occasional microcystic spaces.
- Ancillary: Brenner tumors express GATA3, CK7, p63, S100P, AR, uroplakin, and thrombomodulin, and do not express (or only focally express) CK20.
Reference Gallery:
Brenner tumour. Small nests and cysts in a fibromatous background.
Brenner tumour. Transitional/urothelial nests (some of which show cyst formation) are in a fibromatous stroma.
Brenner tumour. Characteristic cytological features include uniform oval cells with pale cytoplasm, nuclei with occasional grooves, fine chromatin, and small nucleoli.
Benign Brenner tumour. A small, predominantly fibromatous tumour with scattered nests of bland transitional epithelium.
Benign Brenner tumour. Nests of bland transitional epithelium surrounded by dense fibromatous tissue.

Q: Microscopically, the adenofibroma component of Endometrioid Cystadenoma and Adenofibroma is characterized by widely spaced, benign endometrioid glands embedded within a [...] stroma.
Endometrioid adenofibroma. Endometrioid glands are widely spaced within fibromatous stroma.
A: fibromatous
Back Extra: Endometrioid Cystadenoma and Adenofibroma
- Clinical: Patients with Endometrioid Cystadenoma and Adenofibroma may present with symptoms related to a pelvic mass or may be asymptomatic.
- Micro: Endometrioid cystadenomas are usually cysts lined by endometrioid epithelium without underlying endometrial stroma. Adenofibromas have fibromatous stroma containing widely spaced, benign endometrioid glands.
- Ancillary: Ancillary studies are not typically required for the diagnosis of Endometrioid Cystadenoma and Adenofibroma.
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Endometrioid adenofibroma. Endometrioid glands are widely spaced within fibromatous stroma.
Endometrioid adenofibroma. Bland endometrioid glands show focal squamous differentiation.

Q: In Endometrioid Cystadenoma and Adenofibroma, the bland endometrioid glands may histologically demonstrate focal [...] differentiation.
Endometrioid adenofibroma. Bland endometrioid glands show focal squamous differentiation.
A: squamous
Back Extra: Endometrioid Cystadenoma and Adenofibroma
- Clinical: Patients with Endometrioid Cystadenoma and Adenofibroma may present with symptoms related to a pelvic mass or may be asymptomatic.
- Micro: Endometrioid cystadenomas are usually cysts lined by endometrioid epithelium without underlying endometrial stroma. Adenofibromas have fibromatous stroma containing widely spaced, benign endometrioid glands.
- Ancillary: Ancillary studies are not typically required for the diagnosis of Endometrioid Cystadenoma and Adenofibroma.
Reference Gallery:
Endometrioid adenofibroma. Endometrioid glands are widely spaced within fibromatous stroma.
Endometrioid adenofibroma. Bland endometrioid glands show focal squamous differentiation.

Q: A large, smooth-lined multilocular cyst that is microscopically lined by a single layer of tall columnar cells with abundant apical mucin and bland, basally situated nuclei is the classic presentation of [...].
Mucinous cystadenoma. The cyst is lined by tall columnar cells with abundant mucinous cytoplasm and bland basally situated nuclei.
Mucinous cystadenoma of the ovary. A large multilocular cyst with a smooth inner lining.
A: Mucinous cystadenoma and adenofibroma
Back Extra: Mucinous cystadenoma and adenofibroma
- Clinical: Mucinous cystadenoma and adenofibroma most commonly present with abdominal or pelvic pain and symptoms related to an abdominal or pelvic mass.
- Micro: Mucinous cystadenomas are composed of multiple cysts and glands lined by simple non-stratified mucinous epithelium resembling Müllerian, gastric foveolar-type, or intestinal epithelium.
- Ancillary: KRAS mutations are found in a significant number of mucinous cystadenomas and adenofibromas, but diagnostic molecular pathology is not clinically relevant.
Reference Gallery:
Mucinous cystadenoma. The cyst is lined by tall columnar cells with abundant mucinous cytoplasm and bland basally situated nuclei.
Mucinous cystadenoma with mucin granuloma. The mucinous glands are ruptured, with tumour epithelium displaced into stroma and surrounded by extracellular mucin and histiocytes, including multinucleated giant cells. This finding should not be misinterpreted as stromal invasion.
Mucinous adenofibroma. The cut surface is predominantly solid, firm, and white, punctuated with small cysts.
Mucinous cystadenoma. Stromal luteinization. Stromal cells adjacent to the mucinous epithelium show abundant granular eosinophilic or pale cytoplasm and round nuclei.
Mucinous cystadenoma of the ovary. A large multilocular cyst with a smooth inner lining.

Q: In cases of Mucinous cystadenoma and adenofibroma, ruptured glands may displace tumor epithelium into the stroma surrounded by histiocytes and extracellular mucin, forming a [...] that must not be misinterpreted as true stromal invasion.
Mucinous cystadenoma with mucin granuloma. The mucinous glands are ruptured, with tumour epithelium displaced into stroma and surrounded by extracellular mucin and histiocytes, including multinucleated giant cells. This finding should not be misinterpreted as stromal invasion.
A: mucin granuloma
Back Extra: Mucinous cystadenoma and adenofibroma
- Clinical: Mucinous cystadenoma and adenofibroma most commonly present with abdominal or pelvic pain and symptoms related to an abdominal or pelvic mass.
- Micro: Mucinous cystadenomas are composed of multiple cysts and glands lined by simple non-stratified mucinous epithelium resembling Müllerian, gastric foveolar-type, or intestinal epithelium.
- Ancillary: KRAS mutations are found in a significant number of mucinous cystadenomas and adenofibromas, but diagnostic molecular pathology is not clinically relevant.
Reference Gallery:
Mucinous cystadenoma. The cyst is lined by tall columnar cells with abundant mucinous cytoplasm and bland basally situated nuclei.
Mucinous cystadenoma with mucin granuloma. The mucinous glands are ruptured, with tumour epithelium displaced into stroma and surrounded by extracellular mucin and histiocytes, including multinucleated giant cells. This finding should not be misinterpreted as stromal invasion.
Mucinous adenofibroma. The cut surface is predominantly solid, firm, and white, punctuated with small cysts.
Mucinous cystadenoma. Stromal luteinization. Stromal cells adjacent to the mucinous epithelium show abundant granular eosinophilic or pale cytoplasm and round nuclei.
Mucinous cystadenoma of the ovary. A large multilocular cyst with a smooth inner lining.

Q: The adenofibroma variant of Mucinous cystadenoma and adenofibroma is distinguished grossly by a cut surface that is predominantly [...], punctuated only by small cysts, rather than forming large macroscopic cysts.
Mucinous adenofibroma. The cut surface is predominantly solid, firm, and white, punctuated with small cysts.
A: solid and firm
Back Extra: Mucinous cystadenoma and adenofibroma
- Clinical: Mucinous cystadenoma and adenofibroma most commonly present with abdominal or pelvic pain and symptoms related to an abdominal or pelvic mass.
- Micro: Mucinous cystadenomas are composed of multiple cysts and glands lined by simple non-stratified mucinous epithelium resembling Müllerian, gastric foveolar-type, or intestinal epithelium.
- Ancillary: KRAS mutations are found in a significant number of mucinous cystadenomas and adenofibromas, but diagnostic molecular pathology is not clinically relevant.
Reference Gallery:
Mucinous cystadenoma. The cyst is lined by tall columnar cells with abundant mucinous cytoplasm and bland basally situated nuclei.
Mucinous cystadenoma with mucin granuloma. The mucinous glands are ruptured, with tumour epithelium displaced into stroma and surrounded by extracellular mucin and histiocytes, including multinucleated giant cells. This finding should not be misinterpreted as stromal invasion.
Mucinous adenofibroma. The cut surface is predominantly solid, firm, and white, punctuated with small cysts.
Mucinous cystadenoma. Stromal luteinization. Stromal cells adjacent to the mucinous epithelium show abundant granular eosinophilic or pale cytoplasm and round nuclei.
Mucinous cystadenoma of the ovary. A large multilocular cyst with a smooth inner lining.

Q: Microscopically, Seromucinous cystadenoma and adenofibroma is characterized by cysts lined by a mixture of benign Müllerian-type epithelia, classically including ciliated serous, endometrioid, and [...] epithelium.
Seromucinous cystadenoma. Benign seromucinous tumour with cysts lined by mucinous epithelium (right) and attenuated serous-type epithelium (left).
Seromucinous cystadenoma. Benign seromucinous tumour with cysts lined by mucinous epithelium and serous-type epithelium.
A: endocervical-type mucinous
Back Extra: Seromucinous cystadenoma and adenofibroma
- Clinical: Patients typically present with symptoms related to a pelvic mass, or the mass may be an incidental finding on imaging.
- Micro: Seromucinous cystadenomas are composed of cysts lined by a mixture of benign Müllerian-type epithelia, including ciliated, endocervical-type mucinous, and endometrioid. Adenofibromas have a prominent fibromatous hypocellular stroma.
- Ancillary: Differential diagnosis includes other benign ovarian neoplasms such as serous cystadenomas, mucinous cystadenomas, and endometrioid tumors.
Reference Gallery:
Seromucinous cystadenoma. Benign seromucinous tumour with cysts lined by mucinous epithelium (right) and attenuated serous-type epithelium (left).
Seromucinous cystadenoma. Benign seromucinous tumour with cysts lined by mucinous epithelium and serous-type epithelium.

Q: Microscopically, a characteristic finding in Rete Cystadenoma, Adenoma, and Adenocarcinoma is the presence of irregularly spaced crevices lined by non-ciliated cuboidal cells, often accompanied by a distinct band of [...] within the cyst wall.
Rete cyst. The inner wall shows spaced crevices lined by innocuous cuboidal cells lacking cilia. Note the presence of a band of Leydig cells within the cyst wall.
A: Leydig cells
Back Extra: Rete Cystadenoma, Adenoma, and Adenocarcinoma
- Clinical: Rete cystadenoma, adenoma, and adenocarcinoma are typically found in postmenopausal women, often presenting with pelvic/abdominal discomfort or signs of virilization.
- Micro: Rete cysts have irregularly spaced crevices lined by cuboidal cells with minimal nuclear stratification and may contain Leydig cells within the cyst wall.
- Ancillary: Ancillary studies are not clinically relevant for these conditions.
Reference Gallery:
Rete cyst. The inner wall shows spaced crevices lined by innocuous cuboidal cells lacking cilia. Note the presence of a band of Leydig cells within the cyst wall.

Q: Microscopically, Clear Cell Cystadenoma and Adenofibroma features small to medium-sized glands set in a fibromatous stroma, lined by flat or low cuboidal cells that characteristically lack significant [...].
Clear cell adenofibroma. The cells show no significant nuclear atypia.
A: nuclear atypia
Back Extra: Clear Cell Cystadenoma and Adenofibroma
- Clinical: Pure clear cell cystadenoma may be an incidental finding or present with symptoms of a pelvic mass. Median patient age is early in the sixth decade of life (range: 18–63 years).
- Micro: Small to medium-sized glands with bland, flat or low cuboidal cells, clear or eosinophilic, in a fibromatous stroma. Mitotic activity is typically absent.
- Ancillary: Ancillary studies are not clinically relevant for diagnosis.
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Clear cell adenofibroma. The cells show no significant nuclear atypia.

Q: The defining microscopic feature of Serous cystadenoma, adenofibroma, and surface papilloma of the ovary is an epithelial lining of non-stratified cuboidal or columnar cells that resemble [...] secretory or ciliated cells.
Serous cystadenofibroma. Glands lined by bland tubal-type epithelium, with occasional ciliated cells, are present in a fibromatous stroma.
Serous surface papilloma. Stromal papillae covered by bland tubal-type epithelium project from the ovarian surface.
A: tubal
Back Extra: Serous cystadenoma, adenofibroma, and surface papilloma of the ovary
- Clinical: Patients often present with symptoms related to an ovarian mass, or tumours may be found incidentally. Patients present over a wide age range.
- Micro: The epithelial lining of these tumours consists of non-stratified cuboidal or columnar cells resembling tubal secretory or ciliated cells. Serous cystadenofibromas have cysts and broad and simple papillae embedded in prominent fibromatous stroma.
- Ancillary: Not relevant for diagnosis; differential diagnosis includes serous borderline tumours and low-grade serous carcinomas.
Reference Gallery:
Serous cystadenofibroma. Glands lined by bland tubal-type epithelium, with occasional ciliated cells, are present in a fibromatous stroma.
Ovarian serous cystadenofibroma. The tumour is predominantly cystic and the cyst lining is mostly smooth, with some nodular areas.
Serous surface papilloma. Stromal papillae covered by bland tubal-type epithelium project from the ovarian surface.

Q: When evaluating the spectrum of Serous cystadenoma, adenofibroma, and surface papilloma of the ovary, the cystadenofibroma variant specifically exhibits cysts and broad, simple papillae embedded in a prominent [...] stroma.
Serous cystadenofibroma. Glands lined by bland tubal-type epithelium, with occasional ciliated cells, are present in a fibromatous stroma.
Ovarian serous cystadenofibroma. The tumour is predominantly cystic and the cyst lining is mostly smooth, with some nodular areas.
A: fibromatous
Back Extra: Serous cystadenoma, adenofibroma, and surface papilloma of the ovary
- Clinical: Patients often present with symptoms related to an ovarian mass, or tumours may be found incidentally. Patients present over a wide age range.
- Micro: The epithelial lining of these tumours consists of non-stratified cuboidal or columnar cells resembling tubal secretory or ciliated cells. Serous cystadenofibromas have cysts and broad and simple papillae embedded in prominent fibromatous stroma.
- Ancillary: Not relevant for diagnosis; differential diagnosis includes serous borderline tumours and low-grade serous carcinomas.
Reference Gallery:
Serous cystadenofibroma. Glands lined by bland tubal-type epithelium, with occasional ciliated cells, are present in a fibromatous stroma.
Ovarian serous cystadenofibroma. The tumour is predominantly cystic and the cyst lining is mostly smooth, with some nodular areas.
Serous surface papilloma. Stromal papillae covered by bland tubal-type epithelium project from the ovarian surface.

Q: In a solid pseudopapillary tumor, the characteristic histologic appearance includes cellular discohesion resulting in a pseudo-papillary architecture, often accompanied by intracytoplasmic [...].
Solid pseudopapillary tumour. Note the discohesion of cells resulting in a pseudopapillary architecture associated with multiple intracytoplasmic hyaline globules.
A: hyaline globules
Back Extra: Solid pseudopapillary tumour
- Clinical: This rare tumour typically presents as a symptomatic adnexal mass in young to middle-aged women.
- Micro: The tumour shows a characteristic pseudo-papillary architecture with discohesion of cells and intracytoplasmic hyaline globules.
- Ancillary: Tumour cells are positive for vimentin, CD10, CD56, and β-catenin (nuclear and cytoplasmic), and often show CTNNB1 mutations.
Reference Gallery:
Solid pseudopapillary tumour. Note the discohesion of cells resulting in a pseudopapillary architecture associated with multiple intracytoplasmic hyaline globules.
Solid pseudopapillary tumour. Cells may have abundant foamy cytoplasm.

Q: Histologically, the cells of a solid pseudopapillary tumor may exhibit abundant [...] cytoplasm alongside the classic pseudopapillary architecture.
Solid pseudopapillary tumour. Cells may have abundant foamy cytoplasm.
A: foamy
Back Extra: Solid pseudopapillary tumour
- Clinical: This rare tumour typically presents as a symptomatic adnexal mass in young to middle-aged women.
- Micro: The tumour shows a characteristic pseudo-papillary architecture with discohesion of cells and intracytoplasmic hyaline globules.
- Ancillary: Tumour cells are positive for vimentin, CD10, CD56, and β-catenin (nuclear and cytoplasmic), and often show CTNNB1 mutations.
Reference Gallery:
Solid pseudopapillary tumour. Note the discohesion of cells resulting in a pseudopapillary architecture associated with multiple intracytoplasmic hyaline globules.
Solid pseudopapillary tumour. Cells may have abundant foamy cytoplasm.

Q: A solid pseudopapillary tumor is characteristically driven by mutations in the [...] gene, leading to aberrant nuclear and cytoplasmic β-catenin expression.
Solid pseudopapillary tumour. Note the discohesion of cells resulting in a pseudopapillary architecture associated with multiple intracytoplasmic hyaline globules.
Solid pseudopapillary tumour. Cells may have abundant foamy cytoplasm.
A: CTNNB1
Back Extra: Solid pseudopapillary tumour
- Clinical: This rare tumour typically presents as a symptomatic adnexal mass in young to middle-aged women.
- Micro: The tumour shows a characteristic pseudo-papillary architecture with discohesion of cells and intracytoplasmic hyaline globules.
- Ancillary: Tumour cells are positive for vimentin, CD10, CD56, and β-catenin (nuclear and cytoplasmic), and often show CTNNB1 mutations.
Reference Gallery:
Solid pseudopapillary tumour. Note the discohesion of cells resulting in a pseudopapillary architecture associated with multiple intracytoplasmic hyaline globules.
Solid pseudopapillary tumour. Cells may have abundant foamy cytoplasm.

Q: Microscopically, Wolffian tumor of the ovary typically exhibits a mixture of solid areas, well-differentiated tubules, and characteristic [...] (sieve-like) patterns.
Wolffian tumour of the ovary. Note the retiform pattern showing elongated and branching tubules with morphological similarity to the rete ovarii.
Wolffian tumour of the ovary. Note the mixture of solid, retiform, and sieve-like patterns.
A: retiform
Back Extra: Wolffian Tumour of the Ovary
- Clinical: Wolffian tumours of the ovary are typically found incidentally, with a mean patient age of 45.4 years. They can also present with abdominal pain, an abdominal mass, or vaginal bleeding.
- Micro: Microscopically, these tumours are well-circumscribed and composed of spindle cells, tubular structures, retiform (sieve-like) patterns, and multicystic areas. The nuclei are bland, and mitotic activity is low.
- Ancillary: Immunohistochemical studies show diffuse positivity for pankeratin (AE1/AE3) and vimentin, with focal positivity for CK7. GATA3 is usually negative or weakly multifocal.
Reference Gallery:
Wolffian tumour of the ovary. Note the well-differentiated tubules lined by columnar cells without nuclear atypia at higher magnification.
Wolffian tumour of the ovary. Note the retiform pattern showing elongated and branching tubules with morphological similarity to the rete ovarii.
Wolffian tumour of the ovary. Note the mixture of solid, retiform, and sieve-like patterns.
Wolffian tumour of the ovary. Note the well-circumscribed nodule within the ovarian hilum.
Wolffian tumour of the ovary. Note the solid pattern composed of spindle cells without nuclear atypia.

Q: A Wolffian tumor of the ovary characteristically presents as a well-circumscribed nodule that is frequently located within the [...].
Wolffian tumour of the ovary. Note the well-circumscribed nodule within the ovarian hilum.
A: ovarian hilum
Back Extra: Wolffian Tumour of the Ovary
- Clinical: Wolffian tumours of the ovary are typically found incidentally, with a mean patient age of 45.4 years. They can also present with abdominal pain, an abdominal mass, or vaginal bleeding.
- Micro: Microscopically, these tumours are well-circumscribed and composed of spindle cells, tubular structures, retiform (sieve-like) patterns, and multicystic areas. The nuclei are bland, and mitotic activity is low.
- Ancillary: Immunohistochemical studies show diffuse positivity for pankeratin (AE1/AE3) and vimentin, with focal positivity for CK7. GATA3 is usually negative or weakly multifocal.
Reference Gallery:
Wolffian tumour of the ovary. Note the well-differentiated tubules lined by columnar cells without nuclear atypia at higher magnification.
Wolffian tumour of the ovary. Note the retiform pattern showing elongated and branching tubules with morphological similarity to the rete ovarii.
Wolffian tumour of the ovary. Note the mixture of solid, retiform, and sieve-like patterns.
Wolffian tumour of the ovary. Note the well-circumscribed nodule within the ovarian hilum.
Wolffian tumour of the ovary. Note the solid pattern composed of spindle cells without nuclear atypia.

Q: In addition to tubular and sieve-like structures, the solid areas of a Wolffian tumor of the ovary are characteristically composed of bland [...] cells lacking significant nuclear atypia.
Wolffian tumour of the ovary. Note the solid pattern composed of spindle cells without nuclear atypia.
A: spindle
Back Extra: Wolffian Tumour of the Ovary
- Clinical: Wolffian tumours of the ovary are typically found incidentally, with a mean patient age of 45.4 years. They can also present with abdominal pain, an abdominal mass, or vaginal bleeding.
- Micro: Microscopically, these tumours are well-circumscribed and composed of spindle cells, tubular structures, retiform (sieve-like) patterns, and multicystic areas. The nuclei are bland, and mitotic activity is low.
- Ancillary: Immunohistochemical studies show diffuse positivity for pankeratin (AE1/AE3) and vimentin, with focal positivity for CK7. GATA3 is usually negative or weakly multifocal.
Reference Gallery:
Wolffian tumour of the ovary. Note the well-differentiated tubules lined by columnar cells without nuclear atypia at higher magnification.
Wolffian tumour of the ovary. Note the retiform pattern showing elongated and branching tubules with morphological similarity to the rete ovarii.
Wolffian tumour of the ovary. Note the mixture of solid, retiform, and sieve-like patterns.
Wolffian tumour of the ovary. Note the well-circumscribed nodule within the ovarian hilum.
Wolffian tumour of the ovary. Note the solid pattern composed of spindle cells without nuclear atypia.

Q: Microscopically, a Borderline Brenner tumor features prominent papillary or endophytic growth lined by multilayered [...] epithelium, closely resembling a low-grade papillary urothelial neoplasm but lacking stromal invasion.
Borderline Brenner tumour. This tumour shows a prominent papillary growth pattern.
Borderline Brenner tumour. Cytologically, this tumour shows uniform transitional-type epithelium.
Borderline Brenner tumour. The tumour is composed of multiple layers of mildly polymorphic transitional cell–type epithelium but lacks infiltrative growth.
A: transitional-type
Back Extra: Borderline Brenner Tumour
- Clinical: Patients often present with a pelvic mass and are usually > 50 years old.
- Microscopic: The tumour resembles low-grade papillary urothelial neoplasms with uniform transitional-type epithelium and occasional moderate to severe cytological atypia.
- Ancillary: Immunohistochemistry is positive for p63 and GATA3, and negative for ER, PR, and WT1.
Reference Gallery:
Borderline Brenner tumour. This tumour shows a prominent papillary growth pattern.
Borderline Brenner tumour. The papillae are lined by transitional-type epithelium with scattered pleomorphic cells.
Borderline Brenner tumour. This tumour shows an endophytic, ribbon-like growth pattern.
Borderline Brenner tumour. Cytologically, this tumour shows uniform transitional-type epithelium.
Borderline Brenner tumour. The tumour is composed of multiple layers of mildly polymorphic transitional cell–type epithelium but lacks infiltrative growth.

Q: An ovarian neoplasm typically presenting in a patient over 50 years old that features a prominent papillary or endophytic, ribbon-like growth pattern lined by transitional epithelium without infiltrative growth is highly characteristic of a [...].
Borderline Brenner tumour. This tumour shows a prominent papillary growth pattern.
Borderline Brenner tumour. This tumour shows an endophytic, ribbon-like growth pattern.
A: Borderline Brenner tumor
Back Extra: Borderline Brenner Tumour
- Clinical: Patients often present with a pelvic mass and are usually > 50 years old.
- Microscopic: The tumour resembles low-grade papillary urothelial neoplasms with uniform transitional-type epithelium and occasional moderate to severe cytological atypia.
- Ancillary: Immunohistochemistry is positive for p63 and GATA3, and negative for ER, PR, and WT1.
Reference Gallery:
Borderline Brenner tumour. This tumour shows a prominent papillary growth pattern.
Borderline Brenner tumour. The papillae are lined by transitional-type epithelium with scattered pleomorphic cells.
Borderline Brenner tumour. This tumour shows an endophytic, ribbon-like growth pattern.
Borderline Brenner tumour. Cytologically, this tumour shows uniform transitional-type epithelium.
Borderline Brenner tumour. The tumour is composed of multiple layers of mildly polymorphic transitional cell–type epithelium but lacks infiltrative growth.

Q: Microscopically, a Clear Cell Borderline Tumor exhibits variably sized glands and focally crowded nests of cells with clear or eosinophilic cytoplasm, characteristically embedded in a [...] stroma.
Clear cell borderline tumour. Focally crowded nests and glands with clear cells showing low-grade nuclear atypia and prominent nucleoli in a fibromatous stroma.
A: fibromatous
Back Extra: Clear Cell Borderline Tumour
- Clinical: Patients may present with a pelvic mass, increased abdominal girth, and pelvic pain, or the tumour may be an incidental finding.
- Micro: Variably sized glands in a fibromatous stroma, containing low cuboidal or flat cells with enlarged nuclei and clear or eosinophilic cytoplasm.
- Ancillary: Not clinically relevant for diagnosis and management.
Reference Gallery:
Clear cell borderline tumour. Focally crowded nests and glands with clear cells showing low-grade nuclear atypia and prominent nucleoli in a fibromatous stroma.
Clear cell borderline tumour. Peritoneal fluid cytology. Note the epithelial aggregates with nuclear enlargement and overlapping, as well as conspicuous nucleoli.

Q: Peritoneal fluid cytology from a Clear Cell Borderline Tumor typically demonstrates [...] with nuclear enlargement, overlapping, and conspicuous nucleoli.
Clear cell borderline tumour. Peritoneal fluid cytology. Note the epithelial aggregates with nuclear enlargement and overlapping, as well as conspicuous nucleoli.
A: epithelial aggregates
Back Extra: Clear Cell Borderline Tumour
- Clinical: Patients may present with a pelvic mass, increased abdominal girth, and pelvic pain, or the tumour may be an incidental finding.
- Micro: Variably sized glands in a fibromatous stroma, containing low cuboidal or flat cells with enlarged nuclei and clear or eosinophilic cytoplasm.
- Ancillary: Not clinically relevant for diagnosis and management.
Reference Gallery:
Clear cell borderline tumour. Focally crowded nests and glands with clear cells showing low-grade nuclear atypia and prominent nucleoli in a fibromatous stroma.
Clear cell borderline tumour. Peritoneal fluid cytology. Note the epithelial aggregates with nuclear enlargement and overlapping, as well as conspicuous nucleoli.

Q: Microscopically, Endometrioid Borderline Tumor exhibits two primary growth patterns: an intracystic pattern and an [...] pattern characterized by closely packed glands in a fibrous stroma.
Endometrioid borderline tumour. Proliferation of endometrioid glands with intracystic papillary growth embedded in a fibrous stroma.
Endometrioid borderline tumour. Proliferation of endometrioid glands (right) arising in an endometrioid adenofibroma (left).
A: adenofibromatous
Back Extra: Endometrioid Borderline Tumour
- Clinical: Endometrioid borderline tumours are rare, with a mean patient age of 46-55 years. Patients may present with symptoms related to a pelvic mass or the tumour may be an incidental finding.
- Micro: Endometrioid borderline tumours exhibit two growth patterns: adenofibromatous and intracystic. The adenofibromatous pattern shows closely packed, crowded endometrioid glands with mild to moderate cytological atypia and low mitotic activity.
- Ancillary: CTNNB1 mutations are identified in approximately 90% of endometrioid borderline tumours, but diagnostic molecular pathology is not clinically relevant.
Reference Gallery:
Endometrioid borderline tumour. Proliferation of endometrioid glands with intracystic papillary growth embedded in a fibrous stroma.
Endometrioid borderline tumour. Proliferation of endometrioid glands (right) arising in an endometrioid adenofibroma (left).
Endometrioid borderline tumour. Proliferation of endometrial glands with features resembling atypical hyperplasia.
Endometrioid borderline tumour. Proliferation of endometrioid glands with extensive squamous metaplasia.

Q: The glandular proliferation in Endometrioid Borderline Tumor often shows mild to moderate cytological atypia, closely resembling endometrial [...].
Endometrioid borderline tumour. Proliferation of endometrial glands with features resembling atypical hyperplasia.
A: atypical hyperplasia
Back Extra: Endometrioid Borderline Tumour
- Clinical: Endometrioid borderline tumours are rare, with a mean patient age of 46-55 years. Patients may present with symptoms related to a pelvic mass or the tumour may be an incidental finding.
- Micro: Endometrioid borderline tumours exhibit two growth patterns: adenofibromatous and intracystic. The adenofibromatous pattern shows closely packed, crowded endometrioid glands with mild to moderate cytological atypia and low mitotic activity.
- Ancillary: CTNNB1 mutations are identified in approximately 90% of endometrioid borderline tumours, but diagnostic molecular pathology is not clinically relevant.
Reference Gallery:
Endometrioid borderline tumour. Proliferation of endometrioid glands with intracystic papillary growth embedded in a fibrous stroma.
Endometrioid borderline tumour. Proliferation of endometrioid glands (right) arising in an endometrioid adenofibroma (left).
Endometrioid borderline tumour. Proliferation of endometrial glands with features resembling atypical hyperplasia.
Endometrioid borderline tumour. Proliferation of endometrioid glands with extensive squamous metaplasia.

Q: A frequent microscopic finding within the proliferating glands of an Endometrioid Borderline Tumor is the presence of extensive [...].
Endometrioid borderline tumour. Proliferation of endometrioid glands with extensive squamous metaplasia.
A: squamous metaplasia
Back Extra: Endometrioid Borderline Tumour
- Clinical: Endometrioid borderline tumours are rare, with a mean patient age of 46-55 years. Patients may present with symptoms related to a pelvic mass or the tumour may be an incidental finding.
- Micro: Endometrioid borderline tumours exhibit two growth patterns: adenofibromatous and intracystic. The adenofibromatous pattern shows closely packed, crowded endometrioid glands with mild to moderate cytological atypia and low mitotic activity.
- Ancillary: CTNNB1 mutations are identified in approximately 90% of endometrioid borderline tumours, but diagnostic molecular pathology is not clinically relevant.
Reference Gallery:
Endometrioid borderline tumour. Proliferation of endometrioid glands with intracystic papillary growth embedded in a fibrous stroma.
Endometrioid borderline tumour. Proliferation of endometrioid glands (right) arising in an endometrioid adenofibroma (left).
Endometrioid borderline tumour. Proliferation of endometrial glands with features resembling atypical hyperplasia.
Endometrioid borderline tumour. Proliferation of endometrioid glands with extensive squamous metaplasia.

Q: Histologically, a [...] is characterized by cysts lined by gastrointestinal-type mucinous epithelium that exhibits architectural complexity, such as stratification, tufting, and villous papillae.
Mucinous borderline tumour. The cyst lining shows architectural complexity, with some villous architecture and epithelial stratification.
Mucinous borderline tumour. Mucinous borderline tumour lined by stratified epithelium with mild to moderate atypia. Mitotic figures are present.
A: mucinous borderline tumor
Back Extra: Mucinous Borderline Tumour
- Clinical: Patients with mucinous borderline tumour (MBT) often present with symptoms related to an abdominopelvic mass, and the mean age at diagnosis is 45 years.
- Micro: MBT is characterized by multiple cysts lined by gastrointestinal-type mucinous epithelium, showing architectural complexity and variable degrees of stratification, tufting, and villous or slender filiform papillae.
- Ancillary: MBT has an immunohistochemical profile similar to mucinous carcinoma, and anaplastic carcinomas are typically positive for broad-spectrum cytokeratin and EMA.
Reference Gallery:
Mucinous borderline tumour. The cyst lining shows architectural complexity, with some villous architecture and epithelial stratification.
Mucinous borderline tumour with intraepithelial carcinoma. The epithelium has a reduced amount of mucin, an increased N:C ratio, and enlarged nuclei with severe atypia characterized by vesicular chromatin and prominent nucleoli.
Mucinous borderline tumour with microinvasive carcinoma. At the base of the mucinous borderline tumour, a small focus within stroma contains markedly crowded and haphazardly oriented nests. The qualitative features are akin to frankly invasive mucinous carcinoma (infiltrating pattern).
Mucinous borderline tumour. Mucinous borderline tumour lined by stratified epithelium with mild to moderate atypia. Mitotic figures are present.
Ruptured mucinous borderline tumour. Peritoneal fluid cytology shows epithelial aggregates with nuclear stratification, moderate epithelial atypia, and conspicuous nucleoli.
Ruptured mucinous borderline tumour. Peritoneal fluid cytology shows epithelial clusters with nuclear atypia and focal glandular configuration.
Mucinous borderline tumour with microinvasion. The clusters of tumour cells in the area of microinvasion show mild cytological atypia.
Mucinous borderline tumour with microinvasive carcinoma. The clusters of tumour cells in the focus of microinvasive carcinoma show marked cytological atypia.
Mucinous borderline tumour with microinvasion. The clusters of tumour cells in the area of microinvasion measure < 5 mm in linear dimension.

Q: In a mucinous borderline tumor, focal stromal invasion by discrete clusters of neoplastic cells is designated as [...] if the invasive focus measures less than 5 mm in maximal linear dimension.
Mucinous borderline tumour with microinvasion. The clusters of tumour cells in the area of microinvasion show mild cytological atypia.
Mucinous borderline tumour with microinvasion. The clusters of tumour cells in the area of microinvasion measure < 5 mm in linear dimension.
A: microinvasion
Back Extra: Mucinous Borderline Tumour
- Clinical: Patients with mucinous borderline tumour (MBT) often present with symptoms related to an abdominopelvic mass, and the mean age at diagnosis is 45 years.
- Micro: MBT is characterized by multiple cysts lined by gastrointestinal-type mucinous epithelium, showing architectural complexity and variable degrees of stratification, tufting, and villous or slender filiform papillae.
- Ancillary: MBT has an immunohistochemical profile similar to mucinous carcinoma, and anaplastic carcinomas are typically positive for broad-spectrum cytokeratin and EMA.
Reference Gallery:
Mucinous borderline tumour. The cyst lining shows architectural complexity, with some villous architecture and epithelial stratification.
Mucinous borderline tumour with intraepithelial carcinoma. The epithelium has a reduced amount of mucin, an increased N:C ratio, and enlarged nuclei with severe atypia characterized by vesicular chromatin and prominent nucleoli.
Mucinous borderline tumour with microinvasive carcinoma. At the base of the mucinous borderline tumour, a small focus within stroma contains markedly crowded and haphazardly oriented nests. The qualitative features are akin to frankly invasive mucinous carcinoma (infiltrating pattern).
Mucinous borderline tumour. Mucinous borderline tumour lined by stratified epithelium with mild to moderate atypia. Mitotic figures are present.
Ruptured mucinous borderline tumour. Peritoneal fluid cytology shows epithelial aggregates with nuclear stratification, moderate epithelial atypia, and conspicuous nucleoli.
Ruptured mucinous borderline tumour. Peritoneal fluid cytology shows epithelial clusters with nuclear atypia and focal glandular configuration.
Mucinous borderline tumour with microinvasion. The clusters of tumour cells in the area of microinvasion show mild cytological atypia.
Mucinous borderline tumour with microinvasive carcinoma. The clusters of tumour cells in the focus of microinvasive carcinoma show marked cytological atypia.
Mucinous borderline tumour with microinvasion. The clusters of tumour cells in the area of microinvasion measure < 5 mm in linear dimension.

Q: When examining a mucinous borderline tumor, focal areas demonstrating a reduced amount of mucin, increased N:C ratio, and severe nuclear atypia without stromal invasion are classified as [...].
Mucinous borderline tumour with intraepithelial carcinoma. The epithelium has a reduced amount of mucin, an increased N:C ratio, and enlarged nuclei with severe atypia characterized by vesicular chromatin and prominent nucleoli.
A: intraepithelial carcinoma
Back Extra: Mucinous Borderline Tumour
- Clinical: Patients with mucinous borderline tumour (MBT) often present with symptoms related to an abdominopelvic mass, and the mean age at diagnosis is 45 years.
- Micro: MBT is characterized by multiple cysts lined by gastrointestinal-type mucinous epithelium, showing architectural complexity and variable degrees of stratification, tufting, and villous or slender filiform papillae.
- Ancillary: MBT has an immunohistochemical profile similar to mucinous carcinoma, and anaplastic carcinomas are typically positive for broad-spectrum cytokeratin and EMA.
Reference Gallery:
Mucinous borderline tumour. The cyst lining shows architectural complexity, with some villous architecture and epithelial stratification.
Mucinous borderline tumour with intraepithelial carcinoma. The epithelium has a reduced amount of mucin, an increased N:C ratio, and enlarged nuclei with severe atypia characterized by vesicular chromatin and prominent nucleoli.
Mucinous borderline tumour with microinvasive carcinoma. At the base of the mucinous borderline tumour, a small focus within stroma contains markedly crowded and haphazardly oriented nests. The qualitative features are akin to frankly invasive mucinous carcinoma (infiltrating pattern).
Mucinous borderline tumour. Mucinous borderline tumour lined by stratified epithelium with mild to moderate atypia. Mitotic figures are present.
Ruptured mucinous borderline tumour. Peritoneal fluid cytology shows epithelial aggregates with nuclear stratification, moderate epithelial atypia, and conspicuous nucleoli.
Ruptured mucinous borderline tumour. Peritoneal fluid cytology shows epithelial clusters with nuclear atypia and focal glandular configuration.
Mucinous borderline tumour with microinvasion. The clusters of tumour cells in the area of microinvasion show mild cytological atypia.
Mucinous borderline tumour with microinvasive carcinoma. The clusters of tumour cells in the focus of microinvasive carcinoma show marked cytological atypia.
Mucinous borderline tumour with microinvasion. The clusters of tumour cells in the area of microinvasion measure < 5 mm in linear dimension.

Q: A [...] is characterized histologically by hierarchical branching papillae lined by an admixture of two or more Müllerian cell types (e.g., endometrioid, mucinous, ciliated) and frequently exhibits a prominent stromal neutrophilic infiltrate.
Seromucinous borderline tumour. Plump papillae with a neutrophilic infiltrate. Epithelial tufting.
Seromucinous borderline tumour. The epithelial lining consists of Müllerian mucinous cells. A few neutrophils are present in the stroma.
Seromucinous borderline tumour. Admixture of Müllerian-type epithelia with endocervical cells, squamous differentiation, and nondescript eosinophilic cells.
A: seromucinous borderline tumor
Back Extra: Seromucinous borderline tumour
- Clinical: Seromucinous borderline tumours present over a wide age range (mean age: 34–39 years) and are often found incidentally on imaging.
- Micro: These tumours are composed of papillae with hierarchical branching, variably oedematous or fibrous stromal cores, and an admixture of Müllerian cell types including endometrioid, mucinous, ciliated, and clear cells.
- Ancillary: Loss of ARID1A expression and KRAS mutations are common findings in seromucinous borderline tumours.
Reference Gallery:
Seromucinous borderline tumour. Plump papillae with a neutrophilic infiltrate. Epithelial tufting.
Seromucinous borderline tumour. The epithelial lining consists of Müllerian mucinous cells. A few neutrophils are present in the stroma.
Seromucinous borderline tumour. Admixture of Müllerian-type epithelia with endocervical cells, squamous differentiation, and nondescript eosinophilic cells.

Q: In a seromucinous borderline tumor, the hierarchical branching papillae are classically lined by an admixture of [...] cell types (e.g., endometrioid, mucinous, and ciliated cells), often with associated stromal neutrophils.
Seromucinous borderline tumour. The epithelial lining consists of Müllerian mucinous cells. A few neutrophils are present in the stroma.
Seromucinous borderline tumour. Admixture of Müllerian-type epithelia with endocervical cells, squamous differentiation, and nondescript eosinophilic cells.
A: Müllerian
Back Extra: Seromucinous borderline tumour
- Clinical: Seromucinous borderline tumours present over a wide age range (mean age: 34–39 years) and are often found incidentally on imaging.
- Micro: These tumours are composed of papillae with hierarchical branching, variably oedematous or fibrous stromal cores, and an admixture of Müllerian cell types including endometrioid, mucinous, ciliated, and clear cells.
- Ancillary: Loss of ARID1A expression and KRAS mutations are common findings in seromucinous borderline tumours.
Reference Gallery:
Seromucinous borderline tumour. Plump papillae with a neutrophilic infiltrate. Epithelial tufting.
Seromucinous borderline tumour. The epithelial lining consists of Müllerian mucinous cells. A few neutrophils are present in the stroma.
Seromucinous borderline tumour. Admixture of Müllerian-type epithelia with endocervical cells, squamous differentiation, and nondescript eosinophilic cells.

Q: The classic microscopic features of an ovarian mass demonstrating complex papillary architecture with hierarchical branching, stratified epithelium, low-grade nuclear features, and frequent psammoma bodies are characteristic of a [...].
Serous borderline tumour. Papillae are architecturally complex, with hierarchical branching.
Serous borderline tumour. Papillae are lined by stratified epithelium with detached small clusters of tumour cells.
Epithelial-type non-invasive implants associated with ovarian serous borderline tumour. Papillae contain cells with low-grade nuclear features. Psammoma bodies are present.
A: serous borderline tumor of the ovary
Back Extra: Serous borderline tumour of the ovary
- Clinical: Patients with serous borderline tumour of the ovary typically present with an ovarian mass, with a median age of 50 years.
- Micro: Serous borderline tumours are characterized by complex papillary architecture, stratified epithelium, and low-grade nuclear features. Psammoma bodies are commonly seen.
- Ancillary: Somatic mutations of KRAS or BRAF are frequently identified in serous borderline tumours of the ovary.
Reference Gallery:
Serous borderline tumour. Papillae are architecturally complex, with hierarchical branching.
Serous borderline tumour. Papillae are lined by stratified epithelium with detached small clusters of tumour cells.
Micropapillary serous borderline tumour. Micropapillary architecture is prominent.
Micropapillary serous borderline tumour. Elongated micropapillae directly emanate from a large papilla, producing the so-called Medusa head appearance.
Microinvasion in a serous borderline tumour. Small nests and individual tumour cells with abundant eosinophilic cytoplasm (arrows) are present within spaces devoid of epithelial lining in the stroma. This is the most common pattern of microinvasion.
Microinvasive low-grade serous carcinoma. Crowded small and medium-sized papillae in clear lacunar spaces (< 5 mm in greatest extent) are similar to the morphology of an invasive low-grade serous carcinoma.
Endosalpingiosis. Epithelial stratification, cell tufting/detachment, and papillary architecture of epithelial-type non-invasive implants are absent. Endosalpingiosis does not qualify as advanced-stage in the setting of an ovarian serous borderline tumour.
Epithelial-type non-invasive implants associated with ovarian serous borderline tumour. Complex papillary architecture is present within an epithelium-lined space.
Epithelial-type non-invasive implants associated with ovarian serous borderline tumour. Papillae contain cells with low-grade nuclear features. Psammoma bodies are present.
Desmoplastic non-invasive implants associated with ovarian serous borderline tumour. Low-grade simple glands with slight epithelial stratification are present within abundant desmoplastic stroma.
Desmoplastic non-invasive implants associated with ovarian serous borderline tumour. Individual epithelial cells (arrows) are present within abundant desmoplastic stroma. This finding does not fulfil the criteria for invasive implants.
Invasive implants associated with ovarian serous borderline tumour. There is destructive infiltration of underlying tissue. Small papillae and micropapillae are markedly crowded and haphazardly arranged. The histological appearance is akin to that of invasive low-grade serous carcinoma.

Q: The micropapillary variant of a serous borderline tumor of the ovary often features elongated micropapillae directly emanating from a large central papilla, producing a classic [...] appearance.
Micropapillary serous borderline tumour. Micropapillary architecture is prominent.
Micropapillary serous borderline tumour. Elongated micropapillae directly emanate from a large papilla, producing the so-called Medusa head appearance.
A: Medusa head
Back Extra: Serous borderline tumour of the ovary
- Clinical: Patients with serous borderline tumour of the ovary typically present with an ovarian mass, with a median age of 50 years.
- Micro: Serous borderline tumours are characterized by complex papillary architecture, stratified epithelium, and low-grade nuclear features. Psammoma bodies are commonly seen.
- Ancillary: Somatic mutations of KRAS or BRAF are frequently identified in serous borderline tumours of the ovary.
Reference Gallery:
Serous borderline tumour. Papillae are architecturally complex, with hierarchical branching.
Serous borderline tumour. Papillae are lined by stratified epithelium with detached small clusters of tumour cells.
Micropapillary serous borderline tumour. Micropapillary architecture is prominent.
Micropapillary serous borderline tumour. Elongated micropapillae directly emanate from a large papilla, producing the so-called Medusa head appearance.
Microinvasion in a serous borderline tumour. Small nests and individual tumour cells with abundant eosinophilic cytoplasm (arrows) are present within spaces devoid of epithelial lining in the stroma. This is the most common pattern of microinvasion.
Microinvasive low-grade serous carcinoma. Crowded small and medium-sized papillae in clear lacunar spaces (< 5 mm in greatest extent) are similar to the morphology of an invasive low-grade serous carcinoma.
Endosalpingiosis. Epithelial stratification, cell tufting/detachment, and papillary architecture of epithelial-type non-invasive implants are absent. Endosalpingiosis does not qualify as advanced-stage in the setting of an ovarian serous borderline tumour.
Epithelial-type non-invasive implants associated with ovarian serous borderline tumour. Complex papillary architecture is present within an epithelium-lined space.
Epithelial-type non-invasive implants associated with ovarian serous borderline tumour. Papillae contain cells with low-grade nuclear features. Psammoma bodies are present.
Desmoplastic non-invasive implants associated with ovarian serous borderline tumour. Low-grade simple glands with slight epithelial stratification are present within abundant desmoplastic stroma.
Desmoplastic non-invasive implants associated with ovarian serous borderline tumour. Individual epithelial cells (arrows) are present within abundant desmoplastic stroma. This finding does not fulfil the criteria for invasive implants.
Invasive implants associated with ovarian serous borderline tumour. There is destructive infiltration of underlying tissue. Small papillae and micropapillae are markedly crowded and haphazardly arranged. The histological appearance is akin to that of invasive low-grade serous carcinoma.

Q: In the extra-ovarian spread of a serous borderline tumor of the ovary, destructive tissue infiltration by markedly crowded, haphazardly arranged papillae and micropapillae characterizes [...], which appear histologically identical to a low-grade serous carcinoma.
Invasive implants associated with ovarian serous borderline tumour. There is destructive infiltration of underlying tissue. Small papillae and micropapillae are markedly crowded and haphazardly arranged. The histological appearance is akin to that of invasive low-grade serous carcinoma.
A: invasive implants
Back Extra: Serous borderline tumour of the ovary
- Clinical: Patients with serous borderline tumour of the ovary typically present with an ovarian mass, with a median age of 50 years.
- Micro: Serous borderline tumours are characterized by complex papillary architecture, stratified epithelium, and low-grade nuclear features. Psammoma bodies are commonly seen.
- Ancillary: Somatic mutations of KRAS or BRAF are frequently identified in serous borderline tumours of the ovary.
Reference Gallery:
Serous borderline tumour. Papillae are architecturally complex, with hierarchical branching.
Serous borderline tumour. Papillae are lined by stratified epithelium with detached small clusters of tumour cells.
Micropapillary serous borderline tumour. Micropapillary architecture is prominent.
Micropapillary serous borderline tumour. Elongated micropapillae directly emanate from a large papilla, producing the so-called Medusa head appearance.
Microinvasion in a serous borderline tumour. Small nests and individual tumour cells with abundant eosinophilic cytoplasm (arrows) are present within spaces devoid of epithelial lining in the stroma. This is the most common pattern of microinvasion.
Microinvasive low-grade serous carcinoma. Crowded small and medium-sized papillae in clear lacunar spaces (< 5 mm in greatest extent) are similar to the morphology of an invasive low-grade serous carcinoma.
Endosalpingiosis. Epithelial stratification, cell tufting/detachment, and papillary architecture of epithelial-type non-invasive implants are absent. Endosalpingiosis does not qualify as advanced-stage in the setting of an ovarian serous borderline tumour.
Epithelial-type non-invasive implants associated with ovarian serous borderline tumour. Complex papillary architecture is present within an epithelium-lined space.
Epithelial-type non-invasive implants associated with ovarian serous borderline tumour. Papillae contain cells with low-grade nuclear features. Psammoma bodies are present.
Desmoplastic non-invasive implants associated with ovarian serous borderline tumour. Low-grade simple glands with slight epithelial stratification are present within abundant desmoplastic stroma.
Desmoplastic non-invasive implants associated with ovarian serous borderline tumour. Individual epithelial cells (arrows) are present within abundant desmoplastic stroma. This finding does not fulfil the criteria for invasive implants.
Invasive implants associated with ovarian serous borderline tumour. There is destructive infiltration of underlying tissue. Small papillae and micropapillae are markedly crowded and haphazardly arranged. The histological appearance is akin to that of invasive low-grade serous carcinoma.

Q: Microscopically, a Malignant Brenner tumor typically exhibits solid, confluent, or papillary growth of cytologically atypical [...]-type (transitional) cells, often with a desmoplastic stromal reaction and adjacent residual benign components.
Malignant Brenner tumour. Solid confluent and papillary tumour growth with residues of a benign Brenner tumour at the lower edge.
Malignant Brenner tumour. Confluent sheets of tumour with solid growth and pseudoglandular structures.
A: urothelial
Back Extra: Malignant Brenner Tumour
- Clinical: Patients with {{Malignant Brenner Tumour}} typically present with an abdominal mass or pain and may have abnormal vaginal bleeding.
- Micro: Microscopically, {{Malignant Brenner Tumour}} is characterized by irregularly shaped masses of cytologically atypical transitional/urothelial-type cells, sometimes with focal squamous differentiation and a desmoplastic stromal reaction.
- Ancillary: {{Malignant Brenner Tumour}} is usually negative for WT1, negative or weakly positive for ER and PR, and focally positive for p16, with GATA3 being positive in the benign component but negative in the malignant component.
Reference Gallery:
Malignant Brenner tumour. Solid confluent and papillary tumour growth with residues of a benign Brenner tumour at the lower edge.
Malignant Brenner tumour. Confluent sheets of tumour with solid growth and pseudoglandular structures.
Malignant Brenner tumour. GATA3 is positive in the residual benign component but lost in the malignant Brenner tumour.

Q: When evaluating a Malignant Brenner tumor via immunohistochemistry, [...] is characteristically positive in the residual benign component but its expression is lost in the malignant component.
Malignant Brenner tumour. GATA3 is positive in the residual benign component but lost in the malignant Brenner tumour.
A: GATA3
Back Extra: Malignant Brenner Tumour
- Clinical: Patients with {{Malignant Brenner Tumour}} typically present with an abdominal mass or pain and may have abnormal vaginal bleeding.
- Micro: Microscopically, {{Malignant Brenner Tumour}} is characterized by irregularly shaped masses of cytologically atypical transitional/urothelial-type cells, sometimes with focal squamous differentiation and a desmoplastic stromal reaction.
- Ancillary: {{Malignant Brenner Tumour}} is usually negative for WT1, negative or weakly positive for ER and PR, and focally positive for p16, with GATA3 being positive in the benign component but negative in the malignant component.
Reference Gallery:
Malignant Brenner tumour. Solid confluent and papillary tumour growth with residues of a benign Brenner tumour at the lower edge.
Malignant Brenner tumour. Confluent sheets of tumour with solid growth and pseudoglandular structures.
Malignant Brenner tumour. GATA3 is positive in the residual benign component but lost in the malignant Brenner tumour.

Q: Microscopically, Carcinosarcoma of the fallopian tube is defined as a high-grade biphasic neoplasm composed of malignant epithelial elements and malignant [...] elements.
Carcinosarcoma. Mesenchymal component of carcinosarcoma involving the fallopian tube.
Carcinosarcoma involving the fallopian tube. A high-grade mesenchymal component invading the fallopian tube mucosa.
A: mesenchymal
Back Extra: Carcinosarcoma of the fallopian tube
- Clinical: Carcinosarcoma of the fallopian tube presents as a pelvic mass, with symptoms such as abdominal pain or distension.
- Micro: This is a biphasic neoplasm with high-grade epithelial and mesenchymal elements, often with heterologous elements like chondrosarcoma.
- Ancillary: Immunohistochemistry is desirable to confirm specific mesenchymal differentiation, but the diagnosis primarily relies on morphologic criteria.
Reference Gallery:
Carcinosarcoma. Mesenchymal component of carcinosarcoma involving the fallopian tube.
Carcinosarcoma involving the fallopian tube. A high-grade mesenchymal component invading the fallopian tube mucosa.
Carcinosarcoma. Gross appearance of a fallopian tube carcinosarcoma. A tumour mass involving exclusively the fallopian tube.

Q: Clinically manifesting with abdominal pain and a pelvic mass, [...] often presents on gross examination as a solid tumor mass that exclusively expands the adnexal structures.
Carcinosarcoma. Gross appearance of a fallopian tube carcinosarcoma. A tumour mass involving exclusively the fallopian tube.
A: Carcinosarcoma of the fallopian tube
Back Extra: Carcinosarcoma of the fallopian tube
- Clinical: Carcinosarcoma of the fallopian tube presents as a pelvic mass, with symptoms such as abdominal pain or distension.
- Micro: This is a biphasic neoplasm with high-grade epithelial and mesenchymal elements, often with heterologous elements like chondrosarcoma.
- Ancillary: Immunohistochemistry is desirable to confirm specific mesenchymal differentiation, but the diagnosis primarily relies on morphologic criteria.
Reference Gallery:
Carcinosarcoma. Mesenchymal component of carcinosarcoma involving the fallopian tube.
Carcinosarcoma involving the fallopian tube. A high-grade mesenchymal component invading the fallopian tube mucosa.
Carcinosarcoma. Gross appearance of a fallopian tube carcinosarcoma. A tumour mass involving exclusively the fallopian tube.

Q: Histologically, Ovarian Carcinosarcoma characteristically exhibits a [...] pattern, composed of admixed high-grade epithelial and mesenchymal elements.
Carcinosarcoma. A high-grade ovarian tumour with mixed epithelial and mesenchymal elements.
Carcinosarcoma. Two areas of glandular differentiation surrounded by mesenchymal elements.
Ovarian carcinosarcoma. The tumour shows a biphasic pattern, with high-grade epithelial and mesenchymal elements.
A: biphasic
Back Extra: Ovarian Carcinosarcoma
- Clinical: Ovarian carcinosarcomas are typically diagnosed in postmenopausal women, often at an advanced stage, with a poor prognosis.
- Micro: The tumor is biphasic, composed of high-grade carcinoma and sarcoma, often with high-grade serous carcinoma (HGSC) as the epithelial component.
- Ancillary: Genetic alterations in ovarian carcinosarcomas are similar to those in uterine carcinosarcomas, including TP53 deletions and amplifications of PIK3CA, CCNE1, TERT, and MYC.
Reference Gallery:
Ovarian carcinosarcoma. Another example showing a malignant chondroid component as a heterologous element.
Carcinosarcoma. Gross appearance. A large mass involving the ovary.
Ovarian carcinosarcoma. Gross appearance. A solid, necrotic tumour involving the ovary.
Carcinosarcoma. A high-grade ovarian tumour with mixed epithelial and mesenchymal elements.
Carcinosarcoma. Two areas of glandular differentiation surrounded by mesenchymal elements.
Ovarian carcinosarcoma. The tumour shows a biphasic pattern, with high-grade epithelial and mesenchymal elements.

Q: Gross evaluation of an Ovarian Carcinosarcoma typically reveals a large, solid, and extensively [...] tumor mass involving the ovary.
Carcinosarcoma. Gross appearance. A large mass involving the ovary.
Ovarian carcinosarcoma. Gross appearance. A solid, necrotic tumour involving the ovary.
A: necrotic
Back Extra: Ovarian Carcinosarcoma
- Clinical: Ovarian carcinosarcomas are typically diagnosed in postmenopausal women, often at an advanced stage, with a poor prognosis.
- Micro: The tumor is biphasic, composed of high-grade carcinoma and sarcoma, often with high-grade serous carcinoma (HGSC) as the epithelial component.
- Ancillary: Genetic alterations in ovarian carcinosarcomas are similar to those in uterine carcinosarcomas, including TP53 deletions and amplifications of PIK3CA, CCNE1, TERT, and MYC.
Reference Gallery:
Ovarian carcinosarcoma. Another example showing a malignant chondroid component as a heterologous element.
Carcinosarcoma. Gross appearance. A large mass involving the ovary.
Ovarian carcinosarcoma. Gross appearance. A solid, necrotic tumour involving the ovary.
Carcinosarcoma. A high-grade ovarian tumour with mixed epithelial and mesenchymal elements.
Carcinosarcoma. Two areas of glandular differentiation surrounded by mesenchymal elements.
Ovarian carcinosarcoma. The tumour shows a biphasic pattern, with high-grade epithelial and mesenchymal elements.

Q: In Ovarian Carcinosarcoma, the sarcomatous portion may differentiate into heterologous elements, frequently presenting as a malignant [...] component.
Ovarian carcinosarcoma. Another example showing a malignant chondroid component as a heterologous element.
A: chondroid
Back Extra: Ovarian Carcinosarcoma
- Clinical: Ovarian carcinosarcomas are typically diagnosed in postmenopausal women, often at an advanced stage, with a poor prognosis.
- Micro: The tumor is biphasic, composed of high-grade carcinoma and sarcoma, often with high-grade serous carcinoma (HGSC) as the epithelial component.
- Ancillary: Genetic alterations in ovarian carcinosarcomas are similar to those in uterine carcinosarcomas, including TP53 deletions and amplifications of PIK3CA, CCNE1, TERT, and MYC.
Reference Gallery:
Ovarian carcinosarcoma. Another example showing a malignant chondroid component as a heterologous element.
Carcinosarcoma. Gross appearance. A large mass involving the ovary.
Ovarian carcinosarcoma. Gross appearance. A solid, necrotic tumour involving the ovary.
Carcinosarcoma. A high-grade ovarian tumour with mixed epithelial and mesenchymal elements.
Carcinosarcoma. Two areas of glandular differentiation surrounded by mesenchymal elements.
Ovarian carcinosarcoma. The tumour shows a biphasic pattern, with high-grade epithelial and mesenchymal elements.

Q: Microscopically, Clear Cell Carcinoma of the Ovary frequently exhibits tubulocystic or papillary architecture lined by cells with a prominent [...] morphology, characterized by apically placed, protruding nuclei.
Clear cell carcinoma. Tubules lined by a single layer of hobnail cells with eosinophilic cytoplasm.
Clear cell carcinoma, tubulocystic pattern. Cystic glands are lined by a single layer of cuboidal, flattened, and hobnail cells with clear cytoplasm.
A: hobnail
Back Extra: Clear Cell Carcinoma of the Ovary
- Clinical: Clear cell carcinoma of the ovary typically presents in women around 56 years old with symptoms related to a pelvic mass or as an incidental finding. It is associated with paraneoplastic hypercalcemia and venous thromboembolism.
- Micro: Clear cell carcinoma of the ovary shows tubulocystic, papillary, and solid architecture. It is characterized by cells with clear or eosinophilic cytoplasm and hobnail morphology.
- Ancillary: Clear cell carcinoma of the ovary is positive for PAX8, napsin A, and HNF1β, and negative for WT1, ER, and PR. ARID1A loss-of-function mutations are common.
Reference Gallery:
Clear cell carcinoma. Neoplastic glands infiltrating fibromatous stroma.
Clear cell carcinoma. Tubules lined by a single layer of hobnail cells with eosinophilic cytoplasm.
Clear cell carcinoma. Papillary architecture with simple papillae showing stromal hyalinization.
Clear cell carcinoma. Papillae lined by a single layer of cuboidal cells with clear cytoplasm.
Clear cell carcinoma. Solid architecture composed of sheets of clear cells separated by delicate septa.
Clear cell carcinoma. Sheets of polyhedral clear cells with eccentrically placed nuclei. Hyaline bodies are present.
Clear cell carcinoma, tubulocystic pattern. Cystic glands are lined by a single layer of cuboidal, flattened, and hobnail cells with clear cytoplasm.

Q: A characteristic microscopic finding often seen in the papillary patterns of Clear Cell Carcinoma of the Ovary is the presence of prominent stromal [...] within the cores of the simple papillae.
Clear cell carcinoma. Papillary architecture with simple papillae showing stromal hyalinization.
A: hyalinization
Back Extra: Clear Cell Carcinoma of the Ovary
- Clinical: Clear cell carcinoma of the ovary typically presents in women around 56 years old with symptoms related to a pelvic mass or as an incidental finding. It is associated with paraneoplastic hypercalcemia and venous thromboembolism.
- Micro: Clear cell carcinoma of the ovary shows tubulocystic, papillary, and solid architecture. It is characterized by cells with clear or eosinophilic cytoplasm and hobnail morphology.
- Ancillary: Clear cell carcinoma of the ovary is positive for PAX8, napsin A, and HNF1β, and negative for WT1, ER, and PR. ARID1A loss-of-function mutations are common.
Reference Gallery:
Clear cell carcinoma. Neoplastic glands infiltrating fibromatous stroma.
Clear cell carcinoma. Tubules lined by a single layer of hobnail cells with eosinophilic cytoplasm.
Clear cell carcinoma. Papillary architecture with simple papillae showing stromal hyalinization.
Clear cell carcinoma. Papillae lined by a single layer of cuboidal cells with clear cytoplasm.
Clear cell carcinoma. Solid architecture composed of sheets of clear cells separated by delicate septa.
Clear cell carcinoma. Sheets of polyhedral clear cells with eccentrically placed nuclei. Hyaline bodies are present.
Clear cell carcinoma, tubulocystic pattern. Cystic glands are lined by a single layer of cuboidal, flattened, and hobnail cells with clear cytoplasm.

Q: When exhibiting a solid architectural pattern, Clear Cell Carcinoma of the Ovary typically consists of sheets of polyhedral cells with clear cytoplasm, delicate septa, and characteristic extracellular eosinophilic [...].
Clear cell carcinoma. Solid architecture composed of sheets of clear cells separated by delicate septa.
Clear cell carcinoma. Sheets of polyhedral clear cells with eccentrically placed nuclei. Hyaline bodies are present.
A: hyaline bodies
Back Extra: Clear Cell Carcinoma of the Ovary
- Clinical: Clear cell carcinoma of the ovary typically presents in women around 56 years old with symptoms related to a pelvic mass or as an incidental finding. It is associated with paraneoplastic hypercalcemia and venous thromboembolism.
- Micro: Clear cell carcinoma of the ovary shows tubulocystic, papillary, and solid architecture. It is characterized by cells with clear or eosinophilic cytoplasm and hobnail morphology.
- Ancillary: Clear cell carcinoma of the ovary is positive for PAX8, napsin A, and HNF1β, and negative for WT1, ER, and PR. ARID1A loss-of-function mutations are common.
Reference Gallery:
Clear cell carcinoma. Neoplastic glands infiltrating fibromatous stroma.
Clear cell carcinoma. Tubules lined by a single layer of hobnail cells with eosinophilic cytoplasm.
Clear cell carcinoma. Papillary architecture with simple papillae showing stromal hyalinization.
Clear cell carcinoma. Papillae lined by a single layer of cuboidal cells with clear cytoplasm.
Clear cell carcinoma. Solid architecture composed of sheets of clear cells separated by delicate septa.
Clear cell carcinoma. Sheets of polyhedral clear cells with eccentrically placed nuclei. Hyaline bodies are present.
Clear cell carcinoma, tubulocystic pattern. Cystic glands are lined by a single layer of cuboidal, flattened, and hobnail cells with clear cytoplasm.

Q: Microscopically, Endometrioid Carcinoma of the Ovary classically exhibits a confluent, back-to-back arrangement of glands and frequently contains distinct [...].
Endometrioid carcinoma. The lining cells exhibit abundant cytoplasm and low nuclear atypia; squamous morules are present.
Endometrioid carcinoma. Confluent tubular/glandular growth without intervening stroma.
A: squamous morules
Q: Endometrioid Carcinoma of the Ovary
- Clinical: Patients with [...] typically present with a pelvic mass or incidental findings, with a mean age of 55 years. Endometriosis is a significant risk factor.
- Micro: [...] often shows a confluent back-to-back arrangement of glands lined by endometrioid epithelium with low to moderate cytological atypia.
- Ancillary: [...] is usually WT1-negative and positive for hormone receptors (ER/PR).
Reference Gallery:
Endometrioid carcinoma. The lining cells exhibit abundant cytoplasm and low nuclear atypia; squamous morules are present.
Endometrioid carcinoma. Confluent tubular/glandular growth without intervening stroma.
Endometrioid carcinoma. The lining cells exhibit abundant non-mucinous cytoplasm, with moderate atypia and prominent nucleoli.
Endometrioid carcinoma. Solid architecture (grade 3) showing geographical necrosis, which can cause confusion with tubo-ovarian high-grade serous or metastatic colorectal adenocarcinoma.
Endometrioid carcinoma. Solid growth with squamous differentiation and necrosis.
Endometrioid carcinoma. Trabecular pattern resembling a sex cord–stromal tumour.
Endometrioid carcinoma. Trabecular pattern with focal gland formation reminiscent of sex cord–stromal tumour.
Endometrioid carcinoma. Corded and hyalinized pattern, as well as a spindled cell component.
Endometrioid carcinoma. Spindled cells are often seen in the corded and hyalinized pattern.
Endometrioid carcinoma. The tumour exhibits a pronounced papillary architecture.
Endometrioid carcinoma. Papillary pattern, but the cytological atypia is less than in tubo-ovarian high-grade serous carcinoma.
Endometrioid carcinoma. Glandular pattern and secretory changes.
A: Endometrioid Carcinoma of the Ovary; Endometrioid Carcinoma of the Ovary; Endometrioid Carcinoma of the Ovary

Q: Certain architectural variants of Endometrioid Carcinoma of the Ovary exhibit a trabecular or corded pattern that can morphologically mimic a [...].
Endometrioid carcinoma. Trabecular pattern resembling a sex cord–stromal tumour.
Endometrioid carcinoma. Trabecular pattern with focal gland formation reminiscent of sex cord–stromal tumour.
Endometrioid carcinoma. Corded and hyalinized pattern, as well as a spindled cell component.
A: sex cord-stromal tumor
Q: Endometrioid Carcinoma of the Ovary
- Clinical: Patients with [...] typically present with a pelvic mass or incidental findings, with a mean age of 55 years. Endometriosis is a significant risk factor.
- Micro: [...] often shows a confluent back-to-back arrangement of glands lined by endometrioid epithelium with low to moderate cytological atypia.
- Ancillary: [...] is usually WT1-negative and positive for hormone receptors (ER/PR).
Reference Gallery:
Endometrioid carcinoma. The lining cells exhibit abundant cytoplasm and low nuclear atypia; squamous morules are present.
Endometrioid carcinoma. Confluent tubular/glandular growth without intervening stroma.
Endometrioid carcinoma. The lining cells exhibit abundant non-mucinous cytoplasm, with moderate atypia and prominent nucleoli.
Endometrioid carcinoma. Solid architecture (grade 3) showing geographical necrosis, which can cause confusion with tubo-ovarian high-grade serous or metastatic colorectal adenocarcinoma.
Endometrioid carcinoma. Solid growth with squamous differentiation and necrosis.
Endometrioid carcinoma. Trabecular pattern resembling a sex cord–stromal tumour.
Endometrioid carcinoma. Trabecular pattern with focal gland formation reminiscent of sex cord–stromal tumour.
Endometrioid carcinoma. Corded and hyalinized pattern, as well as a spindled cell component.
Endometrioid carcinoma. Spindled cells are often seen in the corded and hyalinized pattern.
Endometrioid carcinoma. The tumour exhibits a pronounced papillary architecture.
Endometrioid carcinoma. Papillary pattern, but the cytological atypia is less than in tubo-ovarian high-grade serous carcinoma.
Endometrioid carcinoma. Glandular pattern and secretory changes.
A: Endometrioid Carcinoma of the Ovary; Endometrioid Carcinoma of the Ovary; Endometrioid Carcinoma of the Ovary

Q: Grade 3 Endometrioid Carcinoma of the Ovary is characterized by a predominantly [...] architecture with geographical necrosis, which can cause confusion with tubo-ovarian high-grade serous or metastatic colorectal adenocarcinoma.
Endometrioid carcinoma. Solid architecture (grade 3) showing geographical necrosis, which can cause confusion with tubo-ovarian high-grade serous or metastatic colorectal adenocarcinoma.
Endometrioid carcinoma. Solid growth with squamous differentiation and necrosis.
A: solid
Q: Endometrioid Carcinoma of the Ovary
- Clinical: Patients with [...] typically present with a pelvic mass or incidental findings, with a mean age of 55 years. Endometriosis is a significant risk factor.
- Micro: [...] often shows a confluent back-to-back arrangement of glands lined by endometrioid epithelium with low to moderate cytological atypia.
- Ancillary: [...] is usually WT1-negative and positive for hormone receptors (ER/PR).
Reference Gallery:
Endometrioid carcinoma. The lining cells exhibit abundant cytoplasm and low nuclear atypia; squamous morules are present.
Endometrioid carcinoma. Confluent tubular/glandular growth without intervening stroma.
Endometrioid carcinoma. The lining cells exhibit abundant non-mucinous cytoplasm, with moderate atypia and prominent nucleoli.
Endometrioid carcinoma. Solid architecture (grade 3) showing geographical necrosis, which can cause confusion with tubo-ovarian high-grade serous or metastatic colorectal adenocarcinoma.
Endometrioid carcinoma. Solid growth with squamous differentiation and necrosis.
Endometrioid carcinoma. Trabecular pattern resembling a sex cord–stromal tumour.
Endometrioid carcinoma. Trabecular pattern with focal gland formation reminiscent of sex cord–stromal tumour.
Endometrioid carcinoma. Corded and hyalinized pattern, as well as a spindled cell component.
Endometrioid carcinoma. Spindled cells are often seen in the corded and hyalinized pattern.
Endometrioid carcinoma. The tumour exhibits a pronounced papillary architecture.
Endometrioid carcinoma. Papillary pattern, but the cytological atypia is less than in tubo-ovarian high-grade serous carcinoma.
Endometrioid carcinoma. Glandular pattern and secretory changes.
A: Endometrioid Carcinoma of the Ovary; Endometrioid Carcinoma of the Ovary; Endometrioid Carcinoma of the Ovary

Q: By definition, the microscopic diagnosis of Mixed Carcinoma of the Ovary requires the clear identification of at least [...] on H&E-stained sections.
Mixed ovarian carcinoma, clear cell carcinoma component. Tubulocystic pattern lined by cuboidal cells with cytoplasmic clearing.
Mixed ovarian carcinoma, endometrioid component. Tubular glands lined by endometrioid-type epithelium.
A: two distinct histological types
Back Extra: Mixed Carcinoma of the Ovary
- Clinical: Patients usually present with symptoms related to an ovarian mass. Mixed ovarian carcinomas are rare (< 1% of ovarian carcinomas in pathological studies).
- Micro: At least two histological types must be clearly recognizable on H&E-stained sections. The different histological components should be confirmed by ancillary testing when appropriate.
- Ancillary: IHC markers such as napsin A (expressed in the clear cell component) and PR (expressed in the endometrioid component) help to discriminate between the two components.
Reference Gallery:
Mixed ovarian carcinoma, clear cell carcinoma component. Tubulocystic pattern lined by cuboidal cells with cytoplasmic clearing.
Mixed ovarian carcinoma, endometrioid component. Tubular glands lined by endometrioid-type epithelium.

Q: The provided micrographs of a Mixed Carcinoma of the Ovary demonstrate an endometrioid component (forming tubular glands) and a [...] component (displaying a tubulocystic pattern with cytoplasmic clearing).
Mixed ovarian carcinoma, clear cell carcinoma component. Tubulocystic pattern lined by cuboidal cells with cytoplasmic clearing.
Mixed ovarian carcinoma, endometrioid component. Tubular glands lined by endometrioid-type epithelium.
A: clear cell
Back Extra: Mixed Carcinoma of the Ovary
- Clinical: Patients usually present with symptoms related to an ovarian mass. Mixed ovarian carcinomas are rare (< 1% of ovarian carcinomas in pathological studies).
- Micro: At least two histological types must be clearly recognizable on H&E-stained sections. The different histological components should be confirmed by ancillary testing when appropriate.
- Ancillary: IHC markers such as napsin A (expressed in the clear cell component) and PR (expressed in the endometrioid component) help to discriminate between the two components.
Reference Gallery:
Mixed ovarian carcinoma, clear cell carcinoma component. Tubulocystic pattern lined by cuboidal cells with cytoplasmic clearing.
Mixed ovarian carcinoma, endometrioid component. Tubular glands lined by endometrioid-type epithelium.

Q: High-grade Serous Carcinoma of the Ovary is characterized by papillary or solid architecture with marked nuclear pleomorphism and almost universally exhibits diffuse immunohistochemical positivity for [...].
High-grade serous carcinoma. Diffuse WT1 expression in a high-grade serous carcinoma with solid and pseudoendometrioid (cribriform) architecture.
High-grade serous carcinoma. Papillary architecture.
High-grade serous carcinoma. Papillary structures containing cells with markedly pleomorphic nuclei and conspicuous mitotic activity.
A: WT1
Back Extra: High-grade Serous Carcinoma of the Ovary
- Clinical: High-grade serous carcinoma (HGSC) of the ovary presents with nonspecific symptoms and often with advanced-stage disease (FIGO stage III or IV) in about 80% of patients.
- Micro: HGSC demonstrates solid, papillary, labyrinthine, glandular, or cribriform architecture, with large, markedly atypical nuclei, high mitotic activity, and frequent necrosis.
- Ancillary: HGSCs exhibit abnormal p53 immunostaining (mutation-type labelling) and diffuse WT1 expression, with nearly every tumour harbouring a deleterious TP53 mutation.
Reference Gallery:
High-grade serous carcinoma. Solid architecture with tumour-infiltrating lymphocytes.
High-grade serous carcinoma. Mutant-pattern p53 immunostaining with strong nuclear expression in almost all tumour cell nuclei (> 80%).
High-grade serous carcinoma. Mutant-pattern p53 immunostaining with complete loss of expression in tumour cells. Note that the retained staining in benign cells serves as an internal control.
High-grade serous carcinoma. Diffuse WT1 expression in a high-grade serous carcinoma with solid and pseudoendometrioid (cribriform) architecture.
High-grade serous carcinoma. Mutant-pattern p53 immunostaining with variable cytoplasmic staining. This is the least common staining pattern seen in high-grade serous carcinoma.
High-grade serous carcinoma. Pleomorphic tumour cells with large cytoplasmic vacuoles and marked nuclear atypia (Diff-Quik).
High-grade serous carcinoma. Intracytoplasmic mucin in some tumour cells (mucicarmine staining).
High-grade serous carcinoma. Prominent clear cell change, mimicking clear cell carcinoma. This finding is often focal, and the clear cell areas show the same immunophenotype as conventional high-grade serous carcinoma.
High-grade serous carcinoma. SET (solid, endometrial-like, transitional) pattern of high-grade serous carcinoma with transitional cell–like architecture.
High-grade serous carcinoma. SET (solid, endometrial-like, transitional) pattern of high-grade serous carcinoma with glandular (pseudoendometrioid) architecture.
High-grade serous carcinoma. Papillary architecture.
High-grade serous carcinoma. Papillary structures containing cells with markedly pleomorphic nuclei and conspicuous mitotic activity.

Q: In High-grade Serous Carcinoma of the Ovary, abnormal immunostaining for [...] (due to an almost ubiquitous deleterious mutation) typically manifests as either strong diffuse nuclear over-expression, complete loss of nuclear expression, or rarely, cytoplasmic staining.
High-grade serous carcinoma. Mutant-pattern p53 immunostaining with strong nuclear expression in almost all tumour cell nuclei (> 80%).
High-grade serous carcinoma. Mutant-pattern p53 immunostaining with complete loss of expression in tumour cells. Note that the retained staining in benign cells serves as an internal control.
High-grade serous carcinoma. Mutant-pattern p53 immunostaining with variable cytoplasmic staining. This is the least common staining pattern seen in high-grade serous carcinoma.
A: p53
Back Extra: High-grade Serous Carcinoma of the Ovary
- Clinical: High-grade serous carcinoma (HGSC) of the ovary presents with nonspecific symptoms and often with advanced-stage disease (FIGO stage III or IV) in about 80% of patients.
- Micro: HGSC demonstrates solid, papillary, labyrinthine, glandular, or cribriform architecture, with large, markedly atypical nuclei, high mitotic activity, and frequent necrosis.
- Ancillary: HGSCs exhibit abnormal p53 immunostaining (mutation-type labelling) and diffuse WT1 expression, with nearly every tumour harbouring a deleterious TP53 mutation.
Reference Gallery:
High-grade serous carcinoma. Solid architecture with tumour-infiltrating lymphocytes.
High-grade serous carcinoma. Mutant-pattern p53 immunostaining with strong nuclear expression in almost all tumour cell nuclei (> 80%).
High-grade serous carcinoma. Mutant-pattern p53 immunostaining with complete loss of expression in tumour cells. Note that the retained staining in benign cells serves as an internal control.
High-grade serous carcinoma. Diffuse WT1 expression in a high-grade serous carcinoma with solid and pseudoendometrioid (cribriform) architecture.
High-grade serous carcinoma. Mutant-pattern p53 immunostaining with variable cytoplasmic staining. This is the least common staining pattern seen in high-grade serous carcinoma.
High-grade serous carcinoma. Pleomorphic tumour cells with large cytoplasmic vacuoles and marked nuclear atypia (Diff-Quik).
High-grade serous carcinoma. Intracytoplasmic mucin in some tumour cells (mucicarmine staining).
High-grade serous carcinoma. Prominent clear cell change, mimicking clear cell carcinoma. This finding is often focal, and the clear cell areas show the same immunophenotype as conventional high-grade serous carcinoma.
High-grade serous carcinoma. SET (solid, endometrial-like, transitional) pattern of high-grade serous carcinoma with transitional cell–like architecture.
High-grade serous carcinoma. SET (solid, endometrial-like, transitional) pattern of high-grade serous carcinoma with glandular (pseudoendometrioid) architecture.
High-grade serous carcinoma. Papillary architecture.
High-grade serous carcinoma. Papillary structures containing cells with markedly pleomorphic nuclei and conspicuous mitotic activity.

Q: A recognized morphological variant of High-grade Serous Carcinoma of the Ovary is the [...] pattern, characterized by solid, endometrial-like (pseudoendometrioid), and transitional cell-like architecture.
High-grade serous carcinoma. SET (solid, endometrial-like, transitional) pattern of high-grade serous carcinoma with transitional cell–like architecture.
High-grade serous carcinoma. SET (solid, endometrial-like, transitional) pattern of high-grade serous carcinoma with glandular (pseudoendometrioid) architecture.
A: SET
Back Extra: High-grade Serous Carcinoma of the Ovary
- Clinical: High-grade serous carcinoma (HGSC) of the ovary presents with nonspecific symptoms and often with advanced-stage disease (FIGO stage III or IV) in about 80% of patients.
- Micro: HGSC demonstrates solid, papillary, labyrinthine, glandular, or cribriform architecture, with large, markedly atypical nuclei, high mitotic activity, and frequent necrosis.
- Ancillary: HGSCs exhibit abnormal p53 immunostaining (mutation-type labelling) and diffuse WT1 expression, with nearly every tumour harbouring a deleterious TP53 mutation.
Reference Gallery:
High-grade serous carcinoma. Solid architecture with tumour-infiltrating lymphocytes.
High-grade serous carcinoma. Mutant-pattern p53 immunostaining with strong nuclear expression in almost all tumour cell nuclei (> 80%).
High-grade serous carcinoma. Mutant-pattern p53 immunostaining with complete loss of expression in tumour cells. Note that the retained staining in benign cells serves as an internal control.
High-grade serous carcinoma. Diffuse WT1 expression in a high-grade serous carcinoma with solid and pseudoendometrioid (cribriform) architecture.
High-grade serous carcinoma. Mutant-pattern p53 immunostaining with variable cytoplasmic staining. This is the least common staining pattern seen in high-grade serous carcinoma.
High-grade serous carcinoma. Pleomorphic tumour cells with large cytoplasmic vacuoles and marked nuclear atypia (Diff-Quik).
High-grade serous carcinoma. Intracytoplasmic mucin in some tumour cells (mucicarmine staining).
High-grade serous carcinoma. Prominent clear cell change, mimicking clear cell carcinoma. This finding is often focal, and the clear cell areas show the same immunophenotype as conventional high-grade serous carcinoma.
High-grade serous carcinoma. SET (solid, endometrial-like, transitional) pattern of high-grade serous carcinoma with transitional cell–like architecture.
High-grade serous carcinoma. SET (solid, endometrial-like, transitional) pattern of high-grade serous carcinoma with glandular (pseudoendometrioid) architecture.
High-grade serous carcinoma. Papillary architecture.
High-grade serous carcinoma. Papillary structures containing cells with markedly pleomorphic nuclei and conspicuous mitotic activity.

Q: Histologically, [...] exhibits uniform tumor cell nuclei with mild to moderate atypia, inconspicuous mitotic activity, and structural patterns such as haphazard micropapillae and small papillae.
Low-grade serous carcinoma. This example shows haphazard micropapillae within spaces. Note the relatively uniform tumour cell nuclei.
Low-grade serous carcinoma. Small papillae containing cells with uniform nuclei and inconspicuous mitotic activity.
A: Low-grade serous carcinoma of the ovary
Back Extra: Low-grade serous carcinoma of the ovary
- Clinical: Patients with low-grade serous carcinoma of the ovary may present with symptoms secondary to mass effect or be asymptomatic. Ascites may be present, and patients are typically younger than those with high-grade serous carcinoma.
- Micro: Low-grade serous carcinoma of the ovary exhibits a variety of patterns, including small nests, glands, papillae, or micropapillae, with mild to moderate nuclear atypia and occasional psammoma bodies.
- Ancillary: Low-grade serous carcinoma of the ovary often exhibits KRAS, NRAS, BRAF, USP9X, and EIF1AX mutations. High-stage tumours are less frequently associated with BRAF mutations, and KRAS mutation is linked to tumour recurrence.
Reference Gallery:
Low-grade serous carcinoma. This example shows haphazard micropapillae within spaces. Note the relatively uniform tumour cell nuclei.
Low-grade serous carcinoma. This example exhibits an inverted macropapillary pattern of invasion. The macropapillae are surrounded by unlined clear spaces. Scattered small papillae, clusters, and individual cells are also present.
Low-grade serous carcinoma. This peritoneal washing specimen shows numerous papillary clusters of uniform cells, as well as psammoma bodies. Note that the findings in this specimen are not diagnostic of low-grade serous carcinoma and could also be seen in association with a serous borderline tumour (H&E on cell block).
Low-grade serous carcinoma. A large multicystic mass with nodular areas and excrescences.
Low-grade serous carcinoma. Small papillae containing cells with uniform nuclei and inconspicuous mitotic activity.

Q: In peritoneal washing specimens of Low-grade serous carcinoma of the ovary, cytology often reveals numerous papillary clusters of uniform cells alongside concentrically laminated calcifications known as [...].
Low-grade serous carcinoma. This peritoneal washing specimen shows numerous papillary clusters of uniform cells, as well as psammoma bodies. Note that the findings in this specimen are not diagnostic of low-grade serous carcinoma and could also be seen in association with a serous borderline tumour (H&E on cell block).
A: psammoma bodies
Back Extra: Low-grade serous carcinoma of the ovary
- Clinical: Patients with low-grade serous carcinoma of the ovary may present with symptoms secondary to mass effect or be asymptomatic. Ascites may be present, and patients are typically younger than those with high-grade serous carcinoma.
- Micro: Low-grade serous carcinoma of the ovary exhibits a variety of patterns, including small nests, glands, papillae, or micropapillae, with mild to moderate nuclear atypia and occasional psammoma bodies.
- Ancillary: Low-grade serous carcinoma of the ovary often exhibits KRAS, NRAS, BRAF, USP9X, and EIF1AX mutations. High-stage tumours are less frequently associated with BRAF mutations, and KRAS mutation is linked to tumour recurrence.
Reference Gallery:
Low-grade serous carcinoma. This example shows haphazard micropapillae within spaces. Note the relatively uniform tumour cell nuclei.
Low-grade serous carcinoma. This example exhibits an inverted macropapillary pattern of invasion. The macropapillae are surrounded by unlined clear spaces. Scattered small papillae, clusters, and individual cells are also present.
Low-grade serous carcinoma. This peritoneal washing specimen shows numerous papillary clusters of uniform cells, as well as psammoma bodies. Note that the findings in this specimen are not diagnostic of low-grade serous carcinoma and could also be seen in association with a serous borderline tumour (H&E on cell block).
Low-grade serous carcinoma. A large multicystic mass with nodular areas and excrescences.
Low-grade serous carcinoma. Small papillae containing cells with uniform nuclei and inconspicuous mitotic activity.

Q: On gross examination, a large multicystic mass with nodular areas and excrescences is characteristic of [...], a tumor that typically affects younger patients and is frequently associated with KRAS or BRAF mutations.
Low-grade serous carcinoma. A large multicystic mass with nodular areas and excrescences.
A: Low-grade serous carcinoma of the ovary
Back Extra: Low-grade serous carcinoma of the ovary
- Clinical: Patients with low-grade serous carcinoma of the ovary may present with symptoms secondary to mass effect or be asymptomatic. Ascites may be present, and patients are typically younger than those with high-grade serous carcinoma.
- Micro: Low-grade serous carcinoma of the ovary exhibits a variety of patterns, including small nests, glands, papillae, or micropapillae, with mild to moderate nuclear atypia and occasional psammoma bodies.
- Ancillary: Low-grade serous carcinoma of the ovary often exhibits KRAS, NRAS, BRAF, USP9X, and EIF1AX mutations. High-stage tumours are less frequently associated with BRAF mutations, and KRAS mutation is linked to tumour recurrence.
Reference Gallery:
Low-grade serous carcinoma. This example shows haphazard micropapillae within spaces. Note the relatively uniform tumour cell nuclei.
Low-grade serous carcinoma. This example exhibits an inverted macropapillary pattern of invasion. The macropapillae are surrounded by unlined clear spaces. Scattered small papillae, clusters, and individual cells are also present.
Low-grade serous carcinoma. This peritoneal washing specimen shows numerous papillary clusters of uniform cells, as well as psammoma bodies. Note that the findings in this specimen are not diagnostic of low-grade serous carcinoma and could also be seen in association with a serous borderline tumour (H&E on cell block).
Low-grade serous carcinoma. A large multicystic mass with nodular areas and excrescences.
Low-grade serous carcinoma. Small papillae containing cells with uniform nuclei and inconspicuous mitotic activity.

Q: A hallmark microscopic finding in Mesonephric-like adenocarcinoma is the presence of varied architectural patterns (e.g., tubular, ductal, papillary) with lumens frequently containing [...].
Ovarian mesonephric-like carcinoma. Varied architectural patterns including tubules lined by cuboidal cells and filled with eosinophilic colloid-like material, as well as angulated glands and papillary structures lined by columnar cells.
Ovarian mesonephric-like carcinoma. Tubular pattern.
A: eosinophilic colloid-like material
Back Extra: Mesonephric-like adenocarcinoma
- Clinical: Mesonephric-like adenocarcinoma presents with pelvic or abdominal pain, primarily in postmenopausal women, and is typically diagnosed at stage I.
- Micro: Histologically, it shows varied patterns including tubular, glandular, ductal, papillary, and solid, often with eosinophilic colloid-like material in the lumen.
- Ancillary: Immunohistochemistry is positive for GATA3, TTF1, CD10, and PAX8, and negative for ER, PR, and WT1. Common molecular alterations include KRAS mutations, loss of 1p, and gain of 1q.
Reference Gallery:
Ovarian mesonephric-like carcinoma. Varied architectural patterns including tubules lined by cuboidal cells and filled with eosinophilic colloid-like material, as well as angulated glands and papillary structures lined by columnar cells.
Ovarian mesonephric-like carcinoma. Tubular pattern.
Ovarian mesonephric-like carcinoma. Mixed ductal and papillary patterns.
Ovarian mesonephric-like carcinoma. Mixed tubular and solid patterns.
Ovarian mesonephric-like carcinoma. GATA3 immunostaining is positive.

Q: In addition to PAX8, CD10, and TTF1, Mesonephric-like adenocarcinoma is characteristically positive for the immunohistochemical marker [...].
Ovarian mesonephric-like carcinoma. GATA3 immunostaining is positive.
A: GATA3
Back Extra: Mesonephric-like adenocarcinoma
- Clinical: Mesonephric-like adenocarcinoma presents with pelvic or abdominal pain, primarily in postmenopausal women, and is typically diagnosed at stage I.
- Micro: Histologically, it shows varied patterns including tubular, glandular, ductal, papillary, and solid, often with eosinophilic colloid-like material in the lumen.
- Ancillary: Immunohistochemistry is positive for GATA3, TTF1, CD10, and PAX8, and negative for ER, PR, and WT1. Common molecular alterations include KRAS mutations, loss of 1p, and gain of 1q.
Reference Gallery:
Ovarian mesonephric-like carcinoma. Varied architectural patterns including tubules lined by cuboidal cells and filled with eosinophilic colloid-like material, as well as angulated glands and papillary structures lined by columnar cells.
Ovarian mesonephric-like carcinoma. Tubular pattern.
Ovarian mesonephric-like carcinoma. Mixed ductal and papillary patterns.
Ovarian mesonephric-like carcinoma. Mixed tubular and solid patterns.
Ovarian mesonephric-like carcinoma. GATA3 immunostaining is positive.

Q: In Mucinous Carcinoma of the Ovary, the expansile (confluent) tumor growth pattern is histologically characterized by marked glandular crowding with minimal to absent stroma, creating a characteristic [...] appearance.
Mucinous carcinoma. The tumour exhibits expansile/confluent growth, with anastomosing/labyrinthine architecture and minimal to absent stroma.
A: labyrinthine
Back Extra: Mucinous Carcinoma of the Ovary
- Clinical: Patients typically present with symptoms related to a pelvic mass. Most tumours are confined to the ovary at presentation, with a median age of 55 years.
- Micro: The expansile/confluent pattern displays marked glandular crowding with little or absent intervening stroma, creating a labyrinthine appearance. The infiltrative/destructive pattern is characterized by irregular glands, nests, and single cells in a desmoplastic stroma.
- Ancillary: Common molecular alterations include copy-number loss of CDKN2A (76%) and KRAS mutations (64%). TP53 mutations occur in 64%, and ERBB2 (HER2) amplifications are detected in 15–26% of tumours.
Reference Gallery:
Mucinous carcinoma. The tumour exhibits expansile/confluent growth, with anastomosing/labyrinthine architecture and minimal to absent stroma.
Mucinous carcinoma. The tumour exhibits infiltrative/destructive growth, with irregularly shaped glands arranged haphazardly within altered stroma.

Q: The infiltrative (destructive) tumor growth pattern of Mucinous Carcinoma of the Ovary features irregularly shaped glands, nests, and single cells haphazardly arranged within a [...] stroma.
Mucinous carcinoma. The tumour exhibits infiltrative/destructive growth, with irregularly shaped glands arranged haphazardly within altered stroma.
A: desmoplastic
Back Extra: Mucinous Carcinoma of the Ovary
- Clinical: Patients typically present with symptoms related to a pelvic mass. Most tumours are confined to the ovary at presentation, with a median age of 55 years.
- Micro: The expansile/confluent pattern displays marked glandular crowding with little or absent intervening stroma, creating a labyrinthine appearance. The infiltrative/destructive pattern is characterized by irregular glands, nests, and single cells in a desmoplastic stroma.
- Ancillary: Common molecular alterations include copy-number loss of CDKN2A (76%) and KRAS mutations (64%). TP53 mutations occur in 64%, and ERBB2 (HER2) amplifications are detected in 15–26% of tumours.
Reference Gallery:
Mucinous carcinoma. The tumour exhibits expansile/confluent growth, with anastomosing/labyrinthine architecture and minimal to absent stroma.
Mucinous carcinoma. The tumour exhibits infiltrative/destructive growth, with irregularly shaped glands arranged haphazardly within altered stroma.

Q: Individuals with Li-Fraumeni Syndrome harbor germline mutations in the [...] tumor suppressor gene, which can present on immunohistochemistry as multiple strongly staining foci in the fallopian tube reflecting loss of heterozygosity.
p53 signatures in the fallopian tube in Li–Fraumeni syndrome. High-power view of a cross-section of fallopian tube from a patient with Li–Fraumeni syndrome. Numerous foci of staining for p53 are present, consistent with focal loss of heterozygosity.
p53 signatures in the fallopian tube in Li–Fraumeni syndrome. Low-power view of a cross-section of fallopian tube from a patient with Li–Fraumeni syndrome. Numerous foci of staining for p53 are present, consistent with focal loss of heterozygosity. The abundance of p53 signatures presumably signifies the vulnerability of the fallopian tube mucosa to stimuli promoting DNA damage. However, malignancy, which requires additional somatic mutations, is rare in the tube.
A: TP53
Back Extra: Li-Fraumeni Syndrome
- Clinical: Li-Fraumeni Syndrome (LFS) is characterized by the early onset of a broad spectrum of cancers, including breast and adrenocortical carcinomas, brain tumours, leukaemia, and soft tissue and bone sarcomas.
- Micro: Gynaecological tumours in LFS are rare but can involve the ovaries, endometrium, cervix, and vagina. A second genetic hit is often required for tumour development in the fallopian tube.
- Ancillary: TP53 germline testing is recommended for individuals with LFS. A broad spectrum of TP53 germline mutations has been found in families with LFS.
Reference Gallery:
p53 signatures in the fallopian tube in Li–Fraumeni syndrome. High-power view of a cross-section of fallopian tube from a patient with Li–Fraumeni syndrome. Numerous foci of staining for p53 are present, consistent with focal loss of heterozygosity.
p53 signatures in the fallopian tube in Li–Fraumeni syndrome. Low-power view of a cross-section of fallopian tube from a patient with Li–Fraumeni syndrome. Numerous foci of staining for p53 are present, consistent with focal loss of heterozygosity. The abundance of p53 signatures presumably signifies the vulnerability of the fallopian tube mucosa to stimuli promoting DNA damage. However, malignancy, which requires additional somatic mutations, is rare in the tube.

Q: Although gynecologic malignancies are relatively rare in Li-Fraumeni Syndrome, immunohistochemistry of the fallopian tube often reveals numerous [...], which represent non-neoplastic foci of altered protein expression due to a second genetic hit.
p53 signatures in the fallopian tube in Li–Fraumeni syndrome. High-power view of a cross-section of fallopian tube from a patient with Li–Fraumeni syndrome. Numerous foci of staining for p53 are present, consistent with focal loss of heterozygosity.
p53 signatures in the fallopian tube in Li–Fraumeni syndrome. Low-power view of a cross-section of fallopian tube from a patient with Li–Fraumeni syndrome. Numerous foci of staining for p53 are present, consistent with focal loss of heterozygosity. The abundance of p53 signatures presumably signifies the vulnerability of the fallopian tube mucosa to stimuli promoting DNA damage. However, malignancy, which requires additional somatic mutations, is rare in the tube.
A: p53 signatures
Back Extra: Li-Fraumeni Syndrome
- Clinical: Li-Fraumeni Syndrome (LFS) is characterized by the early onset of a broad spectrum of cancers, including breast and adrenocortical carcinomas, brain tumours, leukaemia, and soft tissue and bone sarcomas.
- Micro: Gynaecological tumours in LFS are rare but can involve the ovaries, endometrium, cervix, and vagina. A second genetic hit is often required for tumour development in the fallopian tube.
- Ancillary: TP53 germline testing is recommended for individuals with LFS. A broad spectrum of TP53 germline mutations has been found in families with LFS.
Reference Gallery:
p53 signatures in the fallopian tube in Li–Fraumeni syndrome. High-power view of a cross-section of fallopian tube from a patient with Li–Fraumeni syndrome. Numerous foci of staining for p53 are present, consistent with focal loss of heterozygosity.
p53 signatures in the fallopian tube in Li–Fraumeni syndrome. Low-power view of a cross-section of fallopian tube from a patient with Li–Fraumeni syndrome. Numerous foci of staining for p53 are present, consistent with focal loss of heterozygosity. The abundance of p53 signatures presumably signifies the vulnerability of the fallopian tube mucosa to stimuli promoting DNA damage. However, malignancy, which requires additional somatic mutations, is rare in the tube.

Q: Histologically, Small Cell Carcinoma of the Ovary, Hypercalcaemic Type features tumor cells with scant cytoplasm that grow in sheets, nests, and characteristic [...].
Small cell carcinoma of the ovary, hypercalcaemic type. Follicle-like spaces are often present.
Small cell carcinoma of the ovary, hypercalcaemic type. The tumour cells are predominantly monomorphic, have scant cytoplasm, and are loosely cohesive.
A: follicle-like spaces
Back Extra: Small Cell Carcinoma of the Ovary, Hypercalcaemic Type
- Clinical: Two-thirds of patients with Small Cell Carcinoma of the Ovary, Hypercalcaemic Type present with paraneoplastic hypercalcaemia.
- Micro: Tumour cells grow in sheets, nests, cords, and trabeculae, often with follicle-like spaces and brisk mitotic activity.
- Ancillary: Immunohistochemistry shows an absence of SMARCA4 and diffuse expression of WT1, p53, and p16.
Reference Gallery:
Small cell carcinoma of the ovary, hypercalcaemic type. A small cell component with nested growth and focal spindle morphology is juxtaposed to large cells with abundant eosinophilic cytoplasm, some with eccentric nuclei.
Small cell carcinoma of the ovary, hypercalcaemic type. Follicle-like spaces are often present.
Small cell carcinoma of the ovary, hypercalcaemic type. The tumour cells are predominantly monomorphic, have scant cytoplasm, and are loosely cohesive.
Small cell carcinoma of the ovary, hypercalcaemic type. Immunohistochemically, the tumour cells are negative for SMARCA4 (BRG1).

Q: The defining immunohistochemical and molecular feature of Small Cell Carcinoma of the Ovary, Hypercalcaemic Type is the diagnostic loss of [...] (BRG1) expression within the tumor cells.
Small cell carcinoma of the ovary, hypercalcaemic type. Immunohistochemically, the tumour cells are negative for SMARCA4 (BRG1).
A: SMARCA4
Back Extra: Small Cell Carcinoma of the Ovary, Hypercalcaemic Type
- Clinical: Two-thirds of patients with Small Cell Carcinoma of the Ovary, Hypercalcaemic Type present with paraneoplastic hypercalcaemia.
- Micro: Tumour cells grow in sheets, nests, cords, and trabeculae, often with follicle-like spaces and brisk mitotic activity.
- Ancillary: Immunohistochemistry shows an absence of SMARCA4 and diffuse expression of WT1, p53, and p16.
Reference Gallery:
Small cell carcinoma of the ovary, hypercalcaemic type. A small cell component with nested growth and focal spindle morphology is juxtaposed to large cells with abundant eosinophilic cytoplasm, some with eccentric nuclei.
Small cell carcinoma of the ovary, hypercalcaemic type. Follicle-like spaces are often present.
Small cell carcinoma of the ovary, hypercalcaemic type. The tumour cells are predominantly monomorphic, have scant cytoplasm, and are loosely cohesive.
Small cell carcinoma of the ovary, hypercalcaemic type. Immunohistochemically, the tumour cells are negative for SMARCA4 (BRG1).

Q: Gross and microscopic evaluation of a Mature Cystic Teratoma frequently reveals a characteristic solid nodule projecting into the cyst cavity known as the [...].
Mature cystic teratoma. Gross specimen with multicystic appearance. Some cysts are filled with hair and sebaceous material.
Mature cystic teratoma. Mature cystic teratoma commonly contains a solid nodule (the Rokitansky tubercle), which is lined by hair-bearing skin and contains cutaneous adnexal structures and adipose tissue. A variety of other tissues (e.g. neuroglial elements, bone, cartilage, and endodermal tissues) may also be seen within the nodule.
A: Rokitansky tubercle
Back Extra: Mature Cystic Teratoma
- Clinical: Most cases occur in women of reproductive age and often present with abdominal pain or a palpable mass. About 10% of cases are bilateral.
- Micro: Common elements include squamous epithelium, sebaceous glands, hair follicles, neuroectodermal tissues (e.g., glia, ependyma), adipose tissue, bone, cartilage, and respiratory-type epithelium.
- Ancillary: Not clinically relevant; diagnosis is primarily based on gross and microscopic examination.
Reference Gallery:
Mature cystic teratoma. Gross specimen with multicystic appearance. Some cysts are filled with hair and sebaceous material.
Mature cystic teratoma. Squamous epithelium, sebaceous glands, and hair follicles are among the common elements seen in these tumours.
Mature cystic teratoma. Neural-type tissue is one of the common elements seen in these tumours.
Mature cystic teratoma. Mature cystic teratoma commonly contains a solid nodule (the Rokitansky tubercle), which is lined by hair-bearing skin and contains cutaneous adnexal structures and adipose tissue. A variety of other tissues (e.g. neuroglial elements, bone, cartilage, and endodermal tissues) may also be seen within the nodule.
Mature cystic teratoma. This patient presented with anti-NMDAR encephalitis. Prominent lymphoid aggregates with germinal centres surround neuroglial tissue, a finding not generally seen in typical presentations of mature cystic teratoma.
Mature cystic teratoma. Respiratory-type epithelium and glands are among the common elements seen in these tumours.
Mature cystic teratoma. Cartilage and bone are among the common elements seen in these tumours.

Q: Patients with a Mature Cystic Teratoma may rarely present with a paraneoplastic syndrome known as [...], which correlates histologically with prominent lymphoid aggregates and germinal centers surrounding neuroglial tissue.
Mature cystic teratoma. This patient presented with anti-NMDAR encephalitis. Prominent lymphoid aggregates with germinal centres surround neuroglial tissue, a finding not generally seen in typical presentations of mature cystic teratoma.
A: anti-NMDAR encephalitis
Back Extra: Mature Cystic Teratoma
- Clinical: Most cases occur in women of reproductive age and often present with abdominal pain or a palpable mass. About 10% of cases are bilateral.
- Micro: Common elements include squamous epithelium, sebaceous glands, hair follicles, neuroectodermal tissues (e.g., glia, ependyma), adipose tissue, bone, cartilage, and respiratory-type epithelium.
- Ancillary: Not clinically relevant; diagnosis is primarily based on gross and microscopic examination.
Reference Gallery:
Mature cystic teratoma. Gross specimen with multicystic appearance. Some cysts are filled with hair and sebaceous material.
Mature cystic teratoma. Squamous epithelium, sebaceous glands, and hair follicles are among the common elements seen in these tumours.
Mature cystic teratoma. Neural-type tissue is one of the common elements seen in these tumours.
Mature cystic teratoma. Mature cystic teratoma commonly contains a solid nodule (the Rokitansky tubercle), which is lined by hair-bearing skin and contains cutaneous adnexal structures and adipose tissue. A variety of other tissues (e.g. neuroglial elements, bone, cartilage, and endodermal tissues) may also be seen within the nodule.
Mature cystic teratoma. This patient presented with anti-NMDAR encephalitis. Prominent lymphoid aggregates with germinal centres surround neuroglial tissue, a finding not generally seen in typical presentations of mature cystic teratoma.
Mature cystic teratoma. Respiratory-type epithelium and glands are among the common elements seen in these tumours.
Mature cystic teratoma. Cartilage and bone are among the common elements seen in these tumours.

Q: A benign ovarian mass containing fully mature, differentiated tissues derived from multiple germ layers (e.g., squamous epithelium, sebaceous glands, neural tissue, bone, and respiratory epithelium) is diagnostic of a [...].
Mature cystic teratoma. Squamous epithelium, sebaceous glands, and hair follicles are among the common elements seen in these tumours.
Mature cystic teratoma. Neural-type tissue is one of the common elements seen in these tumours.
Mature cystic teratoma. Respiratory-type epithelium and glands are among the common elements seen in these tumours.
A: Mature Cystic Teratoma
Back Extra: Mature Cystic Teratoma
- Clinical: Most cases occur in women of reproductive age and often present with abdominal pain or a palpable mass. About 10% of cases are bilateral.
- Micro: Common elements include squamous epithelium, sebaceous glands, hair follicles, neuroectodermal tissues (e.g., glia, ependyma), adipose tissue, bone, cartilage, and respiratory-type epithelium.
- Ancillary: Not clinically relevant; diagnosis is primarily based on gross and microscopic examination.
Reference Gallery:
Mature cystic teratoma. Gross specimen with multicystic appearance. Some cysts are filled with hair and sebaceous material.
Mature cystic teratoma. Squamous epithelium, sebaceous glands, and hair follicles are among the common elements seen in these tumours.
Mature cystic teratoma. Neural-type tissue is one of the common elements seen in these tumours.
Mature cystic teratoma. Mature cystic teratoma commonly contains a solid nodule (the Rokitansky tubercle), which is lined by hair-bearing skin and contains cutaneous adnexal structures and adipose tissue. A variety of other tissues (e.g. neuroglial elements, bone, cartilage, and endodermal tissues) may also be seen within the nodule.
Mature cystic teratoma. This patient presented with anti-NMDAR encephalitis. Prominent lymphoid aggregates with germinal centres surround neuroglial tissue, a finding not generally seen in typical presentations of mature cystic teratoma.
Mature cystic teratoma. Respiratory-type epithelium and glands are among the common elements seen in these tumours.
Mature cystic teratoma. Cartilage and bone are among the common elements seen in these tumours.

Q: Microscopically, Struma Ovarii is characterized by the presence of variably sized [...] filled with colloid, representing ectopic tissue.
Struma ovarii. Variably sized thyroid follicles filled with colloid and hyperplastic papillae are characteristic of ectopic thyroid tissue.
A: thyroid follicles
Back Extra: Struma Ovarii
- Clinical: Struma ovarii is usually an incidental finding, but can present with signs and symptoms of a pelvic mass, ascites, and rarely hyperthyroidism.
- Micro: Characterized by variably sized thyroid follicles filled with colloid, with hyperplastic changes and occasional papillary, follicular, or anaplastic carcinoma.
- Ancillary: BRAF and KRAS mutations, as well as RET/PTC and PAX8-PPARG rearrangements, may be identified in papillary and follicular carcinomas arising in struma ovarii.
Reference Gallery:
Struma ovarii. A multicystic ovarian tumour filled with colloid/mucoid material.
Struma ovarii. Variably sized thyroid follicles filled with colloid and hyperplastic papillae are characteristic of ectopic thyroid tissue.

Q: Grossly, Struma Ovarii appears as a multicystic ovarian tumor filled with colloid material; clinically, this functional tissue can rarely lead to [...].
Struma ovarii. A multicystic ovarian tumour filled with colloid/mucoid material.
A: hyperthyroidism
Back Extra: Struma Ovarii
- Clinical: Struma ovarii is usually an incidental finding, but can present with signs and symptoms of a pelvic mass, ascites, and rarely hyperthyroidism.
- Micro: Characterized by variably sized thyroid follicles filled with colloid, with hyperplastic changes and occasional papillary, follicular, or anaplastic carcinoma.
- Ancillary: BRAF and KRAS mutations, as well as RET/PTC and PAX8-PPARG rearrangements, may be identified in papillary and follicular carcinomas arising in struma ovarii.
Reference Gallery:
Struma ovarii. A multicystic ovarian tumour filled with colloid/mucoid material.
Struma ovarii. Variably sized thyroid follicles filled with colloid and hyperplastic papillae are characteristic of ectopic thyroid tissue.

Q: In Ovarian Carcinoid, the [...] variant is characterized microscopically by an insular or trabecular growth pattern intimately admixed with benign thyroid follicles.
Strumal carcinoid. Trabecular carcinoid is juxtaposed to cystic thyroid follicles filled with colloid.
A: strumal
Back Extra: Ovarian Carcinoid
- Clinical: Ovarian carcinoid is often diagnosed in postmenopausal women and may present as an incidental finding or with symptoms of a pelvic mass or ascites. Carcinoid syndrome is seen in 30% of insular carcinoid cases.
- Micro: Strumal carcinoid consists of insular or trabecular carcinoid admixed with thyroid follicles. Mucinous carcinoid shows small glands floating in pools of mucin, lined by goblet cells with compressed nuclei.
- Ancillary: Carcinoids are positive for neuroendocrine markers and typically CK7+/CK20−, except for mucinous carcinoids which are CK20+.
Reference Gallery:
Strumal carcinoid. Trabecular carcinoid is juxtaposed to cystic thyroid follicles filled with colloid.
Insular carcinoid. Closely apposed nests punctuated by multiple acini, some displaying eosinophilic secretions. Acini are lined by cells with round nuclei showing salt-and-pepper chromatin. Note the presence of neuroendocrine granules at the base of cells.
Trabecular carcinoid. Interanastomosing trabeculae of uniform cells oriented perpendicularly to the main axis of the trabeculae are separated by minimal amounts of stroma.
Mucinous carcinoid. Note the glands lined by goblet cells with basally located compressed nuclei floating in pools of mucin. There is abundant intermingled fibromatous stroma.

Q: In Ovarian Carcinoid, roughly 30% of cases exhibiting an [...] growth pattern (characterized by closely apposed nests and acini with salt-and-pepper chromatin) present clinically with carcinoid syndrome.
Insular carcinoid. Closely apposed nests punctuated by multiple acini, some displaying eosinophilic secretions. Acini are lined by cells with round nuclei showing salt-and-pepper chromatin. Note the presence of neuroendocrine granules at the base of cells.
A: insular
Back Extra: Ovarian Carcinoid
- Clinical: Ovarian carcinoid is often diagnosed in postmenopausal women and may present as an incidental finding or with symptoms of a pelvic mass or ascites. Carcinoid syndrome is seen in 30% of insular carcinoid cases.
- Micro: Strumal carcinoid consists of insular or trabecular carcinoid admixed with thyroid follicles. Mucinous carcinoid shows small glands floating in pools of mucin, lined by goblet cells with compressed nuclei.
- Ancillary: Carcinoids are positive for neuroendocrine markers and typically CK7+/CK20−, except for mucinous carcinoids which are CK20+.
Reference Gallery:
Strumal carcinoid. Trabecular carcinoid is juxtaposed to cystic thyroid follicles filled with colloid.
Insular carcinoid. Closely apposed nests punctuated by multiple acini, some displaying eosinophilic secretions. Acini are lined by cells with round nuclei showing salt-and-pepper chromatin. Note the presence of neuroendocrine granules at the base of cells.
Trabecular carcinoid. Interanastomosing trabeculae of uniform cells oriented perpendicularly to the main axis of the trabeculae are separated by minimal amounts of stroma.
Mucinous carcinoid. Note the glands lined by goblet cells with basally located compressed nuclei floating in pools of mucin. There is abundant intermingled fibromatous stroma.

Q: Most subtypes of Ovarian Carcinoid are characteristically CK7+/CK20−, but the [...] variant is uniquely CK20+ and features small glands lined by goblet cells floating in pools of extracellular mucin.
Mucinous carcinoid. Note the glands lined by goblet cells with basally located compressed nuclei floating in pools of mucin. There is abundant intermingled fibromatous stroma.
A: mucinous
Back Extra: Ovarian Carcinoid
- Clinical: Ovarian carcinoid is often diagnosed in postmenopausal women and may present as an incidental finding or with symptoms of a pelvic mass or ascites. Carcinoid syndrome is seen in 30% of insular carcinoid cases.
- Micro: Strumal carcinoid consists of insular or trabecular carcinoid admixed with thyroid follicles. Mucinous carcinoid shows small glands floating in pools of mucin, lined by goblet cells with compressed nuclei.
- Ancillary: Carcinoids are positive for neuroendocrine markers and typically CK7+/CK20−, except for mucinous carcinoids which are CK20+.
Reference Gallery:
Strumal carcinoid. Trabecular carcinoid is juxtaposed to cystic thyroid follicles filled with colloid.
Insular carcinoid. Closely apposed nests punctuated by multiple acini, some displaying eosinophilic secretions. Acini are lined by cells with round nuclei showing salt-and-pepper chromatin. Note the presence of neuroendocrine granules at the base of cells.
Trabecular carcinoid. Interanastomosing trabeculae of uniform cells oriented perpendicularly to the main axis of the trabeculae are separated by minimal amounts of stroma.
Mucinous carcinoid. Note the glands lined by goblet cells with basally located compressed nuclei floating in pools of mucin. There is abundant intermingled fibromatous stroma.

Q: Histologically, Dysgerminoma classically features nests of monotonous polygonal tumor cells separated by thin fibrous septa that typically contain a characteristic infiltrate of [...].
Dysgerminoma. Monotonous polygonal tumour cells are arranged in nests defined by thin fibrous septa.
Dysgerminoma. Fibrous septa between aggregates of tumour cells contain variable numbers of lymphocytes.
A: lymphocytes
Back Extra: Dysgerminoma
- Clinical: Dysgerminoma typically presents in children and young women, often with abdominal pain or a mass, and is associated with elevated serum LDH.
- Micro: Monotonous polygonal tumour cells are arranged in nests defined by thin fibrous septa, with prominent nucleoli and frequent mitoses.
- Ancillary: Immunohistochemically, dysgerminoma is positive for SALL4, OCT4, KIT (CD117), and D2-40.
Reference Gallery:
Dysgerminoma. The nuclei of dysgerminoma tumour cells often exhibit angular or squared-off contours and prominent nucleoli. Mitoses are common.
Dysgerminoma. Monotonous polygonal tumour cells are arranged in nests defined by thin fibrous septa.
Dysgerminoma. The tumour cells grow in a corded and trabecular pattern.
Dysgerminoma. Fibrous septa between aggregates of tumour cells contain variable numbers of lymphocytes.
Dysgerminoma. Dysgerminoma exhibits nuclear staining for SALL4 (shown here) and OCT4 (Fig. 13162) and membranous staining for KIT (CD117) (Fig. 13163) and D2-40 (Fig. 13164).
Dysgerminoma. Dysgerminoma exhibits nuclear staining for SALL4 (Fig. 13161) and OCT4 (shown here) and membranous staining for KIT (CD117) (Fig. 13163) and D2-40 (Fig. 13164).
Dysgerminoma. Dysgerminoma exhibits nuclear staining for SALL4 (Fig. 13161) and OCT4 (Fig. 13162) and membranous staining for KIT (CD117) (shown here) and D2-40 (Fig. 13164).
Dysgerminoma. Dysgerminoma exhibits nuclear staining for SALL4 (Fig. 13161) and OCT4 (Fig. 13162) and membranous staining for KIT (CD117) (Fig. 13163) and D2-40 (shown here).
Dysgerminoma. Granulomatous inflammation (epithelioid histiocytes and lymphocytes) in the fibrous septa of dysgerminoma may be extensive in some cases, obscuring the tumour cells.

Q: The immunohistochemical profile of Dysgerminoma is characteristically positive for nuclear markers SALL4 and OCT4, as well as showing membranous staining for D2-40 and [...].
Dysgerminoma. Dysgerminoma exhibits nuclear staining for SALL4 (Fig. 13161) and OCT4 (shown here) and membranous staining for KIT (CD117) (Fig. 13163) and D2-40 (Fig. 13164).
Dysgerminoma. Dysgerminoma exhibits nuclear staining for SALL4 (Fig. 13161) and OCT4 (Fig. 13162) and membranous staining for KIT (CD117) (shown here) and D2-40 (Fig. 13164).
A: CD117
Back Extra: Dysgerminoma
- Clinical: Dysgerminoma typically presents in children and young women, often with abdominal pain or a mass, and is associated with elevated serum LDH.
- Micro: Monotonous polygonal tumour cells are arranged in nests defined by thin fibrous septa, with prominent nucleoli and frequent mitoses.
- Ancillary: Immunohistochemically, dysgerminoma is positive for SALL4, OCT4, KIT (CD117), and D2-40.
Reference Gallery:
Dysgerminoma. The nuclei of dysgerminoma tumour cells often exhibit angular or squared-off contours and prominent nucleoli. Mitoses are common.
Dysgerminoma. Monotonous polygonal tumour cells are arranged in nests defined by thin fibrous septa.
Dysgerminoma. The tumour cells grow in a corded and trabecular pattern.
Dysgerminoma. Fibrous septa between aggregates of tumour cells contain variable numbers of lymphocytes.
Dysgerminoma. Dysgerminoma exhibits nuclear staining for SALL4 (shown here) and OCT4 (Fig. 13162) and membranous staining for KIT (CD117) (Fig. 13163) and D2-40 (Fig. 13164).
Dysgerminoma. Dysgerminoma exhibits nuclear staining for SALL4 (Fig. 13161) and OCT4 (shown here) and membranous staining for KIT (CD117) (Fig. 13163) and D2-40 (Fig. 13164).
Dysgerminoma. Dysgerminoma exhibits nuclear staining for SALL4 (Fig. 13161) and OCT4 (Fig. 13162) and membranous staining for KIT (CD117) (shown here) and D2-40 (Fig. 13164).
Dysgerminoma. Dysgerminoma exhibits nuclear staining for SALL4 (Fig. 13161) and OCT4 (Fig. 13162) and membranous staining for KIT (CD117) (Fig. 13163) and D2-40 (shown here).
Dysgerminoma. Granulomatous inflammation (epithelioid histiocytes and lymphocytes) in the fibrous septa of dysgerminoma may be extensive in some cases, obscuring the tumour cells.

Q: High-power examination of Dysgerminoma reveals tumor cells with angular or squared-off nuclear contours, frequent mitoses, and prominent [...].
Dysgerminoma. The nuclei of dysgerminoma tumour cells often exhibit angular or squared-off contours and prominent nucleoli. Mitoses are common.
A: nucleoli
Back Extra: Dysgerminoma
- Clinical: Dysgerminoma typically presents in children and young women, often with abdominal pain or a mass, and is associated with elevated serum LDH.
- Micro: Monotonous polygonal tumour cells are arranged in nests defined by thin fibrous septa, with prominent nucleoli and frequent mitoses.
- Ancillary: Immunohistochemically, dysgerminoma is positive for SALL4, OCT4, KIT (CD117), and D2-40.
Reference Gallery:
Dysgerminoma. The nuclei of dysgerminoma tumour cells often exhibit angular or squared-off contours and prominent nucleoli. Mitoses are common.
Dysgerminoma. Monotonous polygonal tumour cells are arranged in nests defined by thin fibrous septa.
Dysgerminoma. The tumour cells grow in a corded and trabecular pattern.
Dysgerminoma. Fibrous septa between aggregates of tumour cells contain variable numbers of lymphocytes.
Dysgerminoma. Dysgerminoma exhibits nuclear staining for SALL4 (shown here) and OCT4 (Fig. 13162) and membranous staining for KIT (CD117) (Fig. 13163) and D2-40 (Fig. 13164).
Dysgerminoma. Dysgerminoma exhibits nuclear staining for SALL4 (Fig. 13161) and OCT4 (shown here) and membranous staining for KIT (CD117) (Fig. 13163) and D2-40 (Fig. 13164).
Dysgerminoma. Dysgerminoma exhibits nuclear staining for SALL4 (Fig. 13161) and OCT4 (Fig. 13162) and membranous staining for KIT (CD117) (shown here) and D2-40 (Fig. 13164).
Dysgerminoma. Dysgerminoma exhibits nuclear staining for SALL4 (Fig. 13161) and OCT4 (Fig. 13162) and membranous staining for KIT (CD117) (Fig. 13163) and D2-40 (shown here).
Dysgerminoma. Granulomatous inflammation (epithelioid histiocytes and lymphocytes) in the fibrous septa of dysgerminoma may be extensive in some cases, obscuring the tumour cells.

Q: In Immature Teratoma of the Ovary, the admixed immature tissue components most frequently consist of primitive [...] tubules and rosettes.
Immature teratoma. Immature neuroectodermal tissue is seen adjacent to cartilage.
Immature teratoma. This immature neuroectodermal tissue consists of a rosette composed of primitive, mitotically active cells (arrows) with increased N:C ratios and hyperchromatic nuclei.
A: neuroectodermal
Back Extra: Immature Teratoma of the Ovary
- Clinical: Immature teratoma usually presents as a pelvic mass, typically in the first three decades of life. Elevated serum AFP should prompt more-extensive sampling to rule out yolk sac tumour.
- Micro: The microscopic features include variable amounts of immature tissues, mostly neuroectodermal tubules and rosettes, admixed with ectodermal and endodermal tissues of varying maturation.
- Ancillary: SALL4 can be positive in immature neuroectoderm and intestinal elements. SOX2 and glypican-3 (GPC3) can be positive in neuroectoderm.
Reference Gallery:
Immature teratoma. Immature neuroectodermal tissue is seen adjacent to cartilage.
Immature teratoma. The immature neuroectodermal tissue is mostly solid, with minor areas of rosette formation. Because it occupies > 3 low-power fields in this slide, this example is grade 3.
Immature teratoma. This immature neuroectodermal tissue consists of a rosette composed of primitive, mitotically active cells (arrows) with increased N:C ratios and hyperchromatic nuclei.

Q: The histologic grade of [...] is specifically determined by the quantitative amount of immature neuroectodermal tissue present (e.g., grade 3 tumors exhibit this tissue in > 3 low-power fields).
Immature teratoma. The immature neuroectodermal tissue is mostly solid, with minor areas of rosette formation. Because it occupies > 3 low-power fields in this slide, this example is grade 3.
A: Immature Teratoma of the Ovary
Back Extra: Immature Teratoma of the Ovary
- Clinical: Immature teratoma usually presents as a pelvic mass, typically in the first three decades of life. Elevated serum AFP should prompt more-extensive sampling to rule out yolk sac tumour.
- Micro: The microscopic features include variable amounts of immature tissues, mostly neuroectodermal tubules and rosettes, admixed with ectodermal and endodermal tissues of varying maturation.
- Ancillary: SALL4 can be positive in immature neuroectoderm and intestinal elements. SOX2 and glypican-3 (GPC3) can be positive in neuroectoderm.
Reference Gallery:
Immature teratoma. Immature neuroectodermal tissue is seen adjacent to cartilage.
Immature teratoma. The immature neuroectodermal tissue is mostly solid, with minor areas of rosette formation. Because it occupies > 3 low-power fields in this slide, this example is grade 3.
Immature teratoma. This immature neuroectodermal tissue consists of a rosette composed of primitive, mitotically active cells (arrows) with increased N:C ratios and hyperchromatic nuclei.

Q: The histologic hallmark of Non-gestational choriocarcinoma is an intimate admixture of mononuclear cytotrophoblasts and multinucleated [...], typically accompanied by extensive hemorrhage and necrosis.
Non-gestational choriocarcinoma of ovary. Non-gestational choriocarcinoma of ovary consists of cytotrophoblast and syncytiotrophoblast.
Non-gestational choriocarcinoma of ovary. Non-gestational choriocarcinoma of ovary showing intimate admixture of syncytiotrophoblastic and cytotrophoblastic cells.
A: syncytiotrophoblasts
Back Extra: Non-gestational choriocarcinoma
- Clinical: Non-gestational choriocarcinoma typically presents with abdominal pain, pelvic mass, and vaginal bleeding. Serum β-hCG is usually elevated, and premenarchal patients may have isosexual precocious puberty.
- Micro: The tumour is characterized by an admixture of mononuclear cytotrophoblast and multinucleated syncytiotrophoblast, often with extensive haemorrhage and necrosis.
- Ancillary: STR DNA genotyping can help distinguish non-gestational choriocarcinoma from an ovarian metastasis of gestational choriocarcinoma.
Reference Gallery:
Non-gestational choriocarcinoma of ovary. Non-gestational choriocarcinoma of ovary consists of cytotrophoblast and syncytiotrophoblast.
Non-gestational choriocarcinoma of ovary. Non-gestational choriocarcinoma of ovary showing intimate admixture of syncytiotrophoblastic and cytotrophoblastic cells.

Q: An ovarian germ cell tumor featuring an admixture of cytotrophoblasts and syncytiotrophoblasts in a premenarchal patient with elevated serum β-hCG and isosexual precocious puberty is highly characteristic of [...].
Non-gestational choriocarcinoma of ovary. Non-gestational choriocarcinoma of ovary consists of cytotrophoblast and syncytiotrophoblast.
Non-gestational choriocarcinoma of ovary. Non-gestational choriocarcinoma of ovary showing intimate admixture of syncytiotrophoblastic and cytotrophoblastic cells.
A: Non-gestational choriocarcinoma
Back Extra: Non-gestational choriocarcinoma
- Clinical: Non-gestational choriocarcinoma typically presents with abdominal pain, pelvic mass, and vaginal bleeding. Serum β-hCG is usually elevated, and premenarchal patients may have isosexual precocious puberty.
- Micro: The tumour is characterized by an admixture of mononuclear cytotrophoblast and multinucleated syncytiotrophoblast, often with extensive haemorrhage and necrosis.
- Ancillary: STR DNA genotyping can help distinguish non-gestational choriocarcinoma from an ovarian metastasis of gestational choriocarcinoma.
Reference Gallery:
Non-gestational choriocarcinoma of ovary. Non-gestational choriocarcinoma of ovary consists of cytotrophoblast and syncytiotrophoblast.
Non-gestational choriocarcinoma of ovary. Non-gestational choriocarcinoma of ovary showing intimate admixture of syncytiotrophoblastic and cytotrophoblastic cells.

Q: In Central Primitive Neuroectodermal Tumor, the presence of [...] on histology indicates glial differentiation within a background of primitive small blue cells.
Central-type primitive neuroectodermal tumour. The presence of neuropil indicates glial differentiation in a background of primitive small blue cells.
A: neuropil
Back Extra: Central Primitive Neuroectodermal Tumor
- Clinical: Central Primitive Neuroectodermal Tumor typically presents in younger patients (median age 22 years) with a pelvic mass.
- Micro: These tumours can show a variable degree of neuronal or glial differentiation, and are often positive for CD99, FLI1, and GFAP.
- Ancillary: Essential diagnostic features include membranous CD99 and nuclear FLI1 expression, along with a variable degree of neuroectodermal differentiation.
Reference Gallery:
Central-type primitive neuroectodermal tumour. The presence of neuropil indicates glial differentiation in a background of primitive small blue cells.
Central-type primitive neuroectodermal tumour. Cytoplasmic GFAP staining confirms the presence of neuropil.

Q: In Central Primitive Neuroectodermal Tumor, cytoplasmic staining for [...] is often used to confirm the presence of neuropil and glial differentiation.
Central-type primitive neuroectodermal tumour. Cytoplasmic GFAP staining confirms the presence of neuropil.
A: GFAP
Back Extra: Central Primitive Neuroectodermal Tumor
- Clinical: Central Primitive Neuroectodermal Tumor typically presents in younger patients (median age 22 years) with a pelvic mass.
- Micro: These tumours can show a variable degree of neuronal or glial differentiation, and are often positive for CD99, FLI1, and GFAP.
- Ancillary: Essential diagnostic features include membranous CD99 and nuclear FLI1 expression, along with a variable degree of neuroectodermal differentiation.
Reference Gallery:
Central-type primitive neuroectodermal tumour. The presence of neuropil indicates glial differentiation in a background of primitive small blue cells.
Central-type primitive neuroectodermal tumour. Cytoplasmic GFAP staining confirms the presence of neuropil.

Q: When evaluating Somatic Neoplasms Arising from Teratomas that present as low-grade mucinous epithelial neoplasms, identifying a juxtaposed [...] component (such as fat necrosis) is crucial to exclude metastasis from an appendiceal primary.
Low-grade mucinous epithelial neoplasm (appendiceal-type) arising in a mature cystic teratoma. Tumour cells with tall mucinous cytoplasm and slightly pseudostratified nuclei are detached from the underlying stroma (as seen in secondary involvement by appendiceal tumours). This component is juxtaposed to a sieve-like pattern (fat necrosis with giant cells) typical of mature cystic teratoma.
A: teratomatous
Back Extra: Somatic Neoplasms Arising from Teratomas
- Clinical: Somatic neoplasms arising from teratomas are typically unilateral and occur at an older age (average: 55 years).
- Micro: Squamous cell carcinoma in these neoplasms can range from well-differentiated and keratinizing to poorly differentiated to anaplastic.
- Ancillary: The presence of a teratomatous component is crucial for diagnosis to exclude metastases from appendiceal primaries.
Reference Gallery:
Low-grade mucinous epithelial neoplasm (appendiceal-type) arising in a mature cystic teratoma. Tumour cells with tall mucinous cytoplasm and slightly pseudostratified nuclei are detached from the underlying stroma (as seen in secondary involvement by appendiceal tumours). This component is juxtaposed to a sieve-like pattern (fat necrosis with giant cells) typical of mature cystic teratoma.
Melanoma arising in a mature cystic teratoma. The tumour has spindle and epithelioid morphologies and is associated with abundant pigment. It is present beneath squamous epithelium.

Q: Somatic Neoplasms Arising from Teratomas can occasionally manifest as highly pigmented malignancies like [...], which typically displays spindle and epithelioid morphologies beneath the existing squamous epithelium.
Melanoma arising in a mature cystic teratoma. The tumour has spindle and epithelioid morphologies and is associated with abundant pigment. It is present beneath squamous epithelium.
A: melanoma
Back Extra: Somatic Neoplasms Arising from Teratomas
- Clinical: Somatic neoplasms arising from teratomas are typically unilateral and occur at an older age (average: 55 years).
- Micro: Squamous cell carcinoma in these neoplasms can range from well-differentiated and keratinizing to poorly differentiated to anaplastic.
- Ancillary: The presence of a teratomatous component is crucial for diagnosis to exclude metastases from appendiceal primaries.
Reference Gallery:
Low-grade mucinous epithelial neoplasm (appendiceal-type) arising in a mature cystic teratoma. Tumour cells with tall mucinous cytoplasm and slightly pseudostratified nuclei are detached from the underlying stroma (as seen in secondary involvement by appendiceal tumours). This component is juxtaposed to a sieve-like pattern (fat necrosis with giant cells) typical of mature cystic teratoma.
Melanoma arising in a mature cystic teratoma. The tumour has spindle and epithelioid morphologies and is associated with abundant pigment. It is present beneath squamous epithelium.

Q: In Embryonal Carcinoma, the tumor typically forms solid, nested, glandular, or papillary patterns composed of highly pleomorphic cells that are often intermixed with characteristic [...].
Embryonal carcinoma with glandular and papillary patterns.
Embryonal carcinoma glandular pattern composed of pleomorphic tumour cells and syncytiotrophoblastic giant cells.
A: syncytiotrophoblastic giant cells
Back Extra: Embryonal Carcinoma
- Clinical: Embryonal carcinoma presents in children and young women (average age: 12–15 years) with an abdominal mass and pain, and may cause endocrine alterations such as precocious puberty and menstrual abnormalities.
- Micro: The tumour is composed of monomorphic to pleomorphic cells growing in solid, nested, glandular, and papillary patterns, with hyperchromatic and atypical nuclei and syncytiotrophoblastic giant cells.
- Ancillary: Immunohistochemically, embryonal carcinoma is positive for CD30, OCT4, SALL4, SOX2, and LIN28, and often shows chromosome 12 abnormalities (isochromosome 12p or 12p amplification).
Reference Gallery:
Embryonal carcinoma with glandular and papillary patterns.
Embryonal carcinoma glandular pattern composed of pleomorphic tumour cells and syncytiotrophoblastic giant cells.
CD30 stains embryonal carcinoma in a membranous pattern.
SOX2 stains embryonal carcinoma in a nuclear pattern.

Q: To help distinguish Embryonal Carcinoma from other germ cell tumors, pathologists rely on its characteristic membranous immunohistochemical positivity for [...].
CD30 stains embryonal carcinoma in a membranous pattern.
A: CD30
Back Extra: Embryonal Carcinoma
- Clinical: Embryonal carcinoma presents in children and young women (average age: 12–15 years) with an abdominal mass and pain, and may cause endocrine alterations such as precocious puberty and menstrual abnormalities.
- Micro: The tumour is composed of monomorphic to pleomorphic cells growing in solid, nested, glandular, and papillary patterns, with hyperchromatic and atypical nuclei and syncytiotrophoblastic giant cells.
- Ancillary: Immunohistochemically, embryonal carcinoma is positive for CD30, OCT4, SALL4, SOX2, and LIN28, and often shows chromosome 12 abnormalities (isochromosome 12p or 12p amplification).
Reference Gallery:
Embryonal carcinoma with glandular and papillary patterns.
Embryonal carcinoma glandular pattern composed of pleomorphic tumour cells and syncytiotrophoblastic giant cells.
CD30 stains embryonal carcinoma in a membranous pattern.
SOX2 stains embryonal carcinoma in a nuclear pattern.

Q: In addition to broad germ cell markers like OCT4 and SALL4, Embryonal Carcinoma classically exhibits strong nuclear immunohistochemical staining for [...].
SOX2 stains embryonal carcinoma in a nuclear pattern.
A: SOX2
Back Extra: Embryonal Carcinoma
- Clinical: Embryonal carcinoma presents in children and young women (average age: 12–15 years) with an abdominal mass and pain, and may cause endocrine alterations such as precocious puberty and menstrual abnormalities.
- Micro: The tumour is composed of monomorphic to pleomorphic cells growing in solid, nested, glandular, and papillary patterns, with hyperchromatic and atypical nuclei and syncytiotrophoblastic giant cells.
- Ancillary: Immunohistochemically, embryonal carcinoma is positive for CD30, OCT4, SALL4, SOX2, and LIN28, and often shows chromosome 12 abnormalities (isochromosome 12p or 12p amplification).
Reference Gallery:
Embryonal carcinoma with glandular and papillary patterns.
Embryonal carcinoma glandular pattern composed of pleomorphic tumour cells and syncytiotrophoblastic giant cells.
CD30 stains embryonal carcinoma in a membranous pattern.
SOX2 stains embryonal carcinoma in a nuclear pattern.

Q: A pathognomonic histologic feature of Yolk Sac Tumor is the [...], which consists of a tumor cell-lined papilla with a large central vessel occupying a cystic space.
Yolk sac tumour. The Schiller–Duval body is a tumour cell–lined papilla with a large central vessel, occupying a cystic space within endodermal sinus–pattern yolk sac tumour.
A: Schiller-Duval body
Back Extra: Yolk Sac Tumor
- Clinical: Yolk sac tumors (YSTs) typically present in the second and third decades with abdominal pain and/or a pelvic mass. Elevated serum AFP levels are commonly seen.
- Micro: The reticular/microcystic pattern is the most common, characterized by anastomosing spaces and cysts lined by a single layer of tumour cells. Other patterns include endodermal sinus, papillary, and glandular.
- Ancillary: YSTs are positive for SALL4, LIN28, AFP (often focal and weak), glypican-3 (GPC3), and ZBTB16. About 75% of cases show chromosome 12 abnormalities, predominantly isochromosome 12p.
Reference Gallery:
Yolk sac tumour. Yolk sac tumour typically exhibits multiple patterns: reticular/microcystic pattern (top), endodermal sinus pattern (centre), and endometrioid-like glandular pattern (bottom).
Yolk sac tumour. The polyvesicular vitelline pattern of yolk sac tumour is a honeycomb-like pattern of numerous variably sized vesicles and cysts within fibrous stroma.
Yolk sac tumour. The Schiller–Duval body is a tumour cell–lined papilla with a large central vessel, occupying a cystic space within endodermal sinus–pattern yolk sac tumour.
Yolk sac tumour. Papillary pattern.
Yolk sac tumour. The reticular/microcystic pattern consists of interanastomosing spaces and cysts lined by tumour cells.
Yolk sac tumour. Eosinophilic hyaline globules are common in yolk sac tumour, although not specific for this tumour type.
Yolk sac tumour. Glypican-3 (GPC3) immunohistochemistry.

Q: The most common histologic pattern in Yolk Sac Tumor is the [...] pattern, which is characterized by an anastomosing network of spaces and cysts.
Yolk sac tumour. Yolk sac tumour typically exhibits multiple patterns: reticular/microcystic pattern (top), endodermal sinus pattern (centre), and endometrioid-like glandular pattern (bottom).
Yolk sac tumour. The reticular/microcystic pattern consists of interanastomosing spaces and cysts lined by tumour cells.
A: reticular/microcystic
Back Extra: Yolk Sac Tumor
- Clinical: Yolk sac tumors (YSTs) typically present in the second and third decades with abdominal pain and/or a pelvic mass. Elevated serum AFP levels are commonly seen.
- Micro: The reticular/microcystic pattern is the most common, characterized by anastomosing spaces and cysts lined by a single layer of tumour cells. Other patterns include endodermal sinus, papillary, and glandular.
- Ancillary: YSTs are positive for SALL4, LIN28, AFP (often focal and weak), glypican-3 (GPC3), and ZBTB16. About 75% of cases show chromosome 12 abnormalities, predominantly isochromosome 12p.
Reference Gallery:
Yolk sac tumour. Yolk sac tumour typically exhibits multiple patterns: reticular/microcystic pattern (top), endodermal sinus pattern (centre), and endometrioid-like glandular pattern (bottom).
Yolk sac tumour. The polyvesicular vitelline pattern of yolk sac tumour is a honeycomb-like pattern of numerous variably sized vesicles and cysts within fibrous stroma.
Yolk sac tumour. The Schiller–Duval body is a tumour cell–lined papilla with a large central vessel, occupying a cystic space within endodermal sinus–pattern yolk sac tumour.
Yolk sac tumour. Papillary pattern.
Yolk sac tumour. The reticular/microcystic pattern consists of interanastomosing spaces and cysts lined by tumour cells.
Yolk sac tumour. Eosinophilic hyaline globules are common in yolk sac tumour, although not specific for this tumour type.
Yolk sac tumour. Glypican-3 (GPC3) immunohistochemistry.

Q: Immunohistochemically, Yolk Sac Tumor is typically positive for AFP, SALL4, LIN28, and the highly characteristic marker [...] (GPC3).
Yolk sac tumour. Glypican-3 (GPC3) immunohistochemistry.
A: glypican-3
Back Extra: Yolk Sac Tumor
- Clinical: Yolk sac tumors (YSTs) typically present in the second and third decades with abdominal pain and/or a pelvic mass. Elevated serum AFP levels are commonly seen.
- Micro: The reticular/microcystic pattern is the most common, characterized by anastomosing spaces and cysts lined by a single layer of tumour cells. Other patterns include endodermal sinus, papillary, and glandular.
- Ancillary: YSTs are positive for SALL4, LIN28, AFP (often focal and weak), glypican-3 (GPC3), and ZBTB16. About 75% of cases show chromosome 12 abnormalities, predominantly isochromosome 12p.
Reference Gallery:
Yolk sac tumour. Yolk sac tumour typically exhibits multiple patterns: reticular/microcystic pattern (top), endodermal sinus pattern (centre), and endometrioid-like glandular pattern (bottom).
Yolk sac tumour. The polyvesicular vitelline pattern of yolk sac tumour is a honeycomb-like pattern of numerous variably sized vesicles and cysts within fibrous stroma.
Yolk sac tumour. The Schiller–Duval body is a tumour cell–lined papilla with a large central vessel, occupying a cystic space within endodermal sinus–pattern yolk sac tumour.
Yolk sac tumour. Papillary pattern.
Yolk sac tumour. The reticular/microcystic pattern consists of interanastomosing spaces and cysts lined by tumour cells.
Yolk sac tumour. Eosinophilic hyaline globules are common in yolk sac tumour, although not specific for this tumour type.
Yolk sac tumour. Glypican-3 (GPC3) immunohistochemistry.

Q: Histologically, Burkitt lymphoma is classically characterized by a [...] pattern due to the presence of numerous tingible-body macrophages interspersed among diffuse sheets of monotonous medium-sized lymphoid cells.
Burkitt lymphoma. Characteristic histology with diffuse sheets of monotonous medium-sized lymphoid cells with numerous tingible-body macrophages, giving the so-called starry-sky appearance.
A: starry-sky
Back Extra: Burkitt lymphoma
- Clinical: Patients often present acutely with bulky disease, and Burkitt lymphoma accounts for 5–20% of lymphomas involving the female genital tract.
- Micro: Characterized by diffuse sheets of monotonous medium-sized lymphoid cells with high mitotic activity and apoptosis, resulting in a starry-sky pattern due to the presence of numerous tingible-body macrophages.
- Ancillary: Essential diagnostic criteria include MYC gene rearrangement, B-cell markers (CD19, CD20, CD22, CD79a, PAX5), and a high Ki-67 proliferation index (> 95%).
Reference Gallery:
Burkitt lymphoma. Characteristic histology with diffuse sheets of monotonous medium-sized lymphoid cells with numerous tingible-body macrophages, giving the so-called starry-sky appearance.
Burkitt lymphoma involving ovaries. Medium-sized lymphoid cells are interspersed with macrophages. They possess multiple small nucleoli and amphophilic cytoplasm.

Q: A fast-growing B-cell neoplasm that can present as bulky disease in the ovaries and features monotonous medium-sized lymphoid cells with amphophilic cytoplasm and multiple small nucleoli is known as [...].
Burkitt lymphoma involving ovaries. Medium-sized lymphoid cells are interspersed with macrophages. They possess multiple small nucleoli and amphophilic cytoplasm.
A: Burkitt lymphoma
Back Extra: Burkitt lymphoma
- Clinical: Patients often present acutely with bulky disease, and Burkitt lymphoma accounts for 5–20% of lymphomas involving the female genital tract.
- Micro: Characterized by diffuse sheets of monotonous medium-sized lymphoid cells with high mitotic activity and apoptosis, resulting in a starry-sky pattern due to the presence of numerous tingible-body macrophages.
- Ancillary: Essential diagnostic criteria include MYC gene rearrangement, B-cell markers (CD19, CD20, CD22, CD79a, PAX5), and a high Ki-67 proliferation index (> 95%).
Reference Gallery:
Burkitt lymphoma. Characteristic histology with diffuse sheets of monotonous medium-sized lymphoid cells with numerous tingible-body macrophages, giving the so-called starry-sky appearance.
Burkitt lymphoma involving ovaries. Medium-sized lymphoid cells are interspersed with macrophages. They possess multiple small nucleoli and amphophilic cytoplasm.

Q: In primary ovarian Follicular Lymphoma, the tumor typically exhibits a growth pattern of back-to-back follicles replacing the parenchyma, composed predominantly of [...].
Primary ovarian follicular lymphoma. Low-power view. Back-to-back follicles composed predominantly of centrocytes (inset) replace the ovarian parenchyma.
A: centrocytes
Back Extra: Follicular Lymphoma
- Clinical: Follicular lymphoma in the female genital tract (FGT) presents with localized masses and is often indolent, with a 5-year cancer-specific survival rate of 88.6%.
- Micro: Primary ovarian follicular lymphoma shows a mixed diffuse and follicular growth pattern, with back-to-back follicles composed predominantly of centrocytes.
- Ancillary: The characteristic t(14;18)(q32;q21) translocation is less common in primary ovarian follicular lymphoma compared to secondary involvement.
Reference Gallery:
Primary ovarian follicular lymphoma. The neoplastic cells express CD20.
Primary ovarian follicular lymphoma. The neoplastic B cells express CD10. Both follicular and interfollicular B cells are positive.
Primary ovarian follicular lymphoma. The neoplastic follicles lack BCL2 expression, a characteristic feature of primary ovarian follicular lymphoma.
Primary ovarian follicular lymphoma. Low-power view. Back-to-back follicles composed predominantly of centrocytes (inset) replace the ovarian parenchyma.

Q: Unlike typical nodal disease, primary ovarian Follicular Lymphoma characteristically lacks the expression of [...] by immunohistochemistry.
Primary ovarian follicular lymphoma. The neoplastic follicles lack BCL2 expression, a characteristic feature of primary ovarian follicular lymphoma.
A: BCL2
Back Extra: Follicular Lymphoma
- Clinical: Follicular lymphoma in the female genital tract (FGT) presents with localized masses and is often indolent, with a 5-year cancer-specific survival rate of 88.6%.
- Micro: Primary ovarian follicular lymphoma shows a mixed diffuse and follicular growth pattern, with back-to-back follicles composed predominantly of centrocytes.
- Ancillary: The characteristic t(14;18)(q32;q21) translocation is less common in primary ovarian follicular lymphoma compared to secondary involvement.
Reference Gallery:
Primary ovarian follicular lymphoma. The neoplastic cells express CD20.
Primary ovarian follicular lymphoma. The neoplastic B cells express CD10. Both follicular and interfollicular B cells are positive.
Primary ovarian follicular lymphoma. The neoplastic follicles lack BCL2 expression, a characteristic feature of primary ovarian follicular lymphoma.
Primary ovarian follicular lymphoma. Low-power view. Back-to-back follicles composed predominantly of centrocytes (inset) replace the ovarian parenchyma.

Q: The neoplastic B cells in primary ovarian Follicular Lymphoma are positive for CD20 and [...], which highlights both the follicular and interfollicular areas.
Primary ovarian follicular lymphoma. The neoplastic cells express CD20.
Primary ovarian follicular lymphoma. The neoplastic B cells express CD10. Both follicular and interfollicular B cells are positive.
A: CD10
Back Extra: Follicular Lymphoma
- Clinical: Follicular lymphoma in the female genital tract (FGT) presents with localized masses and is often indolent, with a 5-year cancer-specific survival rate of 88.6%.
- Micro: Primary ovarian follicular lymphoma shows a mixed diffuse and follicular growth pattern, with back-to-back follicles composed predominantly of centrocytes.
- Ancillary: The characteristic t(14;18)(q32;q21) translocation is less common in primary ovarian follicular lymphoma compared to secondary involvement.
Reference Gallery:
Primary ovarian follicular lymphoma. The neoplastic cells express CD20.
Primary ovarian follicular lymphoma. The neoplastic B cells express CD10. Both follicular and interfollicular B cells are positive.
Primary ovarian follicular lymphoma. The neoplastic follicles lack BCL2 expression, a characteristic feature of primary ovarian follicular lymphoma.
Primary ovarian follicular lymphoma. Low-power view. Back-to-back follicles composed predominantly of centrocytes (inset) replace the ovarian parenchyma.

Q: Histologically, Low-Grade Endometrioid Stromal Sarcoma often arises from a background of endometriosis and is characterized by a diffuse proliferation of uniform, small cells with [...] and inconspicuous nucleoli.
Low-grade endometrioid stromal sarcoma arising from endometriosis. Tumour cells grow in sheets; they are small and uniform, with bland cytological features. The tumour is juxtaposed to endometriosis.
A: bland oval nuclei
Q: Low-Grade Endometrioid Stromal Sarcoma
- Clinical: Patients are typically perimenopausal or postmenopausal and present with abdominal swelling or pain. These tumours arise from endometriosis and have genetic alterations similar to their uterine counterparts, including [...] rearrangements.
- Micro: The tumour shows a diffuse growth of uniform small cells, sometimes whorling around arteriole-like vessels. Cells are small with [...]; mitotic activity is typically low.
- Ancillary: These tumours typically express [...] with variable expression of keratin, nuclear WT1, and actins. Desmin is positive in areas of smooth muscle differentiation.
Reference Gallery:
Low-grade endometrioid stromal sarcoma arising from endometriosis. Tumour cells grow in sheets; they are small and uniform, with bland cytological features. The tumour is juxtaposed to endometriosis.
A: JAZF1-SUZ12 (JJAZ1), EPC1-PHF1, and PHF1; bland oval nuclei and inconspicuous nucleoli; CD10, ER, and PR

Q: Extrauterine Low-Grade Endometrioid Stromal Sarcoma typically arises from a background of [...], presenting microscopically as sheets of small, uniform cells juxtaposed to the precursor lesion.
Low-grade endometrioid stromal sarcoma arising from endometriosis. Tumour cells grow in sheets; they are small and uniform, with bland cytological features. The tumour is juxtaposed to endometriosis.
A: endometriosis
Q: Low-Grade Endometrioid Stromal Sarcoma
- Clinical: Patients are typically perimenopausal or postmenopausal and present with abdominal swelling or pain. These tumours arise from endometriosis and have genetic alterations similar to their uterine counterparts, including [...] rearrangements.
- Micro: The tumour shows a diffuse growth of uniform small cells, sometimes whorling around arteriole-like vessels. Cells are small with [...]; mitotic activity is typically low.
- Ancillary: These tumours typically express [...] with variable expression of keratin, nuclear WT1, and actins. Desmin is positive in areas of smooth muscle differentiation.
Reference Gallery:
Low-grade endometrioid stromal sarcoma arising from endometriosis. Tumour cells grow in sheets; they are small and uniform, with bland cytological features. The tumour is juxtaposed to endometriosis.
A: JAZF1-SUZ12 (JJAZ1), EPC1-PHF1, and PHF1; bland oval nuclei and inconspicuous nucleoli; CD10, ER, and PR

Q: Histologically, Ovarian Fibrosarcoma is characterized by densely hypercellular and disorderly fascicles of spindle cells with moderate to marked nuclear atypia and numerous [...].
Ovarian fibrosarcoma. Markedly atypical spindle cells with numerous mitoses.
A: mitotic figures
Back Extra: Ovarian Fibrosarcoma
- Clinical: Most patients are postmenopausal and present with symptoms attributable to a pelvic or abdominal mass. These are extremely rare ovarian neoplasms.
- Micro: Neoplasms are densely hypercellular with disorderly fascicles of spindle cells, moderate to marked nuclear atypia, and numerous mitotic figures.
- Ancillary: Ovarian fibrosarcomas may exhibit positive staining (usually focal) with calretinin or inhibin and are usually negative for CD10.
Reference Gallery:
Ovarian fibrosarcoma. Markedly atypical spindle cells with numerous mitoses.

Q: When evaluating Smooth Muscle Tumours of the Ovary, the microscopic finding of a well-circumscribed tumor featuring intersecting short fascicles of bland, uniform spindled cells is characteristic of a benign [...].
Cellular leiomyoma. The tumour is well circumscribed from adjacent ovarian parenchyma. It is cellular, with uniform elongated and bland tumour cells forming intersecting fascicles.
A: leiomyoma
Back Extra: Smooth Muscle Tumours of the Ovary
- Clinical: Smooth muscle tumours of the ovary can present in reproductive-aged to postmenopausal women, often with a pelvic mass or signs of Meigs syndrome.
- Micro: Leiomyomas are characterized by intersecting short fascicles of bland spindled cells, while leiomyosarcomas show hypercellularity, cytological atypia, and brisk mitotic activity.
- Ancillary: Immunohistochemical studies show positivity for smooth muscle markers, ER, and PR.
Reference Gallery:
Cellular leiomyoma. The tumour is well circumscribed from adjacent ovarian parenchyma. It is cellular, with uniform elongated and bland tumour cells forming intersecting fascicles.

Q: Microscopically, Wilms tumor classically exhibits a [...] morphology, characterized by a combination of blastemal, epithelial, and mesenchymal elements.
Wilms tumour of the ovary. Spindle cell component.
Wilms tumour of the ovary. Epithelial and blastemal components.
A: triphasic
Back Extra: Wilms Tumour
- Clinical: The usual presentation is abdominal pain or a palpable mass. Rare cases present with menorrhagia, calf pain due to deep venous thrombosis, or fever.
- Micro: Wilms tumour typically shows a combination of blastemal, epithelial, and mesenchymal elements. The blastemal component consists of densely packed cells with scant cytoplasm, and the epithelial component includes rosette-like structures and tubules.
- Ancillary: Immunohistochemically, the blastemal and epithelial components are positive for WT1, PAX8, CAM5.2, and CD56, while the epithelial cells are positive for cytokeratins.
Reference Gallery:
Wilms tumour of the ovary. Spindle cell component.
Wilms tumour of the ovary. Epithelial and blastemal components.

Q: Within the characteristic histology of Wilms tumor, the densely packed blastemal cells are often seen alongside an epithelial component that typically organizes into rosette-like structures and primitive [...].
Wilms tumour of the ovary. Epithelial and blastemal components.
A: tubules
Back Extra: Wilms Tumour
- Clinical: The usual presentation is abdominal pain or a palpable mass. Rare cases present with menorrhagia, calf pain due to deep venous thrombosis, or fever.
- Micro: Wilms tumour typically shows a combination of blastemal, epithelial, and mesenchymal elements. The blastemal component consists of densely packed cells with scant cytoplasm, and the epithelial component includes rosette-like structures and tubules.
- Ancillary: Immunohistochemically, the blastemal and epithelial components are positive for WT1, PAX8, CAM5.2, and CD56, while the epithelial cells are positive for cytokeratins.
Reference Gallery:
Wilms tumour of the ovary. Spindle cell component.
Wilms tumour of the ovary. Epithelial and blastemal components.

Q: The mesenchymal component of a Wilms tumor frequently consists of a primitive [...] proliferation, as seen microscopically.
Wilms tumour of the ovary. Spindle cell component.
A: spindle cell
Back Extra: Wilms Tumour
- Clinical: The usual presentation is abdominal pain or a palpable mass. Rare cases present with menorrhagia, calf pain due to deep venous thrombosis, or fever.
- Micro: Wilms tumour typically shows a combination of blastemal, epithelial, and mesenchymal elements. The blastemal component consists of densely packed cells with scant cytoplasm, and the epithelial component includes rosette-like structures and tubules.
- Ancillary: Immunohistochemically, the blastemal and epithelial components are positive for WT1, PAX8, CAM5.2, and CD56, while the epithelial cells are positive for cytokeratins.
Reference Gallery:
Wilms tumour of the ovary. Spindle cell component.
Wilms tumour of the ovary. Epithelial and blastemal components.

Q: Adenosarcoma of the Ovary is a biphasic tumor characterized by mildly atypical cellular stroma forming polypoid projections into cystic spaces, imparting a striking [...] appearance at low magnification.
Adenosarcoma. The tumour shows polypoid projections of cellular stroma into a large cystic space lined by endometrioid-type epithelium associated with squamous metaplasia.
Adenosarcoma. At lower magnification, the tumour shows a striking phyllodes-like configuration.
A: phyllodes-like
Back Extra: Adenosarcoma of the Ovary
- Clinical: Patients are typically early postmenopausal with an adnexal mass, vaginal bleeding, or incidental findings.
- Micro: The glands are often elongated, compressed, and branching, giving a phyllodes-like appearance. The stroma may form polypoid projections within cysts, and the stromal cells may show mild to moderate cytological atypia.
- Ancillary: The stromal component is typically positive for CD10, WT1, ER, and PR. High-grade sarcomatous overgrowth areas are usually negative for these markers.
Reference Gallery:
Adenosarcoma. The tumour shows polypoid projections of cellular stroma into a large cystic space lined by endometrioid-type epithelium associated with squamous metaplasia.
Adenosarcoma. At lower magnification, the tumour shows a striking phyllodes-like configuration.

Q: Adenosarcoma of the Ovary classically exhibits cellular stromal projections that protrude into large cysts lined by benign [...]-type epithelium, which may occasionally show squamous metaplasia.
Adenosarcoma. The tumour shows polypoid projections of cellular stroma into a large cystic space lined by endometrioid-type epithelium associated with squamous metaplasia.
A: endometrioid
Back Extra: Adenosarcoma of the Ovary
- Clinical: Patients are typically early postmenopausal with an adnexal mass, vaginal bleeding, or incidental findings.
- Micro: The glands are often elongated, compressed, and branching, giving a phyllodes-like appearance. The stroma may form polypoid projections within cysts, and the stromal cells may show mild to moderate cytological atypia.
- Ancillary: The stromal component is typically positive for CD10, WT1, ER, and PR. High-grade sarcomatous overgrowth areas are usually negative for these markers.
Reference Gallery:
Adenosarcoma. The tumour shows polypoid projections of cellular stroma into a large cystic space lined by endometrioid-type epithelium associated with squamous metaplasia.
Adenosarcoma. At lower magnification, the tumour shows a striking phyllodes-like configuration.

Q: Microscopically, Mixed Germ Cell-Sex Cord-Stromal Tumor, Unclassified is characterized by a haphazard admixture of smaller sex cord cells forming cords or tubules, and large [...] which possess pleomorphic nuclei and ample cytoplasm.
Mixed germ cell–sex cord–stromal tumour, unclassified. Mixed germ cell–sex cord–stromal tumour showing an admixture of germ cell and sex cord components arranged in a haphazard fashion. The germ cells are large, with pleomorphic nuclei and ample cytoplasm, resembling dysgerminoma tumour cells. The smaller sex cord cells surround the germ cells, forming cords or trabeculae.
A: germ cells
Back Extra: Mixed Germ Cell-Sex Cord-Stromal Tumour, Unclassified
- Clinical: Most tumours occur in infants or children aged < 10 years, and are occasionally associated with isosexual pseudoprecocity.
- Micro: The tumour shows a variable and haphazard admixture of large germ cells with pleomorphic nuclei and ample cytoplasm, and smaller sex cord cells forming cords, trabeculae, or tubules.
- Ancillary: Immunohistochemically, the sex cord elements are typically positive for inhibin, and the germ cells are immunoreactive for PLAP, OCT4, and KIT.
Reference Gallery:
Mixed germ cell–sex cord–stromal tumour, unclassified. Mixed germ cell–sex cord–stromal tumour showing an admixture of germ cell and sex cord components arranged in a haphazard fashion. The germ cells are large, with pleomorphic nuclei and ample cytoplasm, resembling dysgerminoma tumour cells. The smaller sex cord cells surround the germ cells, forming cords or trabeculae.
Mixed germ cell–sex cord–stromal tumour, unclassified. Mixed germ cell–sex cord–stromal tumour, unclassified, showing an admixture of germ cells and sex cord cells (top left and right). Sex cord cells also grow in clustered hollow or solid tubules (centre and bottom).

Q: A pediatric neoplasm presenting with a haphazard microscopic admixture of large, pleomorphic germ cells and smaller sex cord cells arranged in clustered solid or hollow tubules is characteristic of [...].
Mixed germ cell–sex cord–stromal tumour, unclassified. Mixed germ cell–sex cord–stromal tumour showing an admixture of germ cell and sex cord components arranged in a haphazard fashion. The germ cells are large, with pleomorphic nuclei and ample cytoplasm, resembling dysgerminoma tumour cells. The smaller sex cord cells surround the germ cells, forming cords or trabeculae.
Mixed germ cell–sex cord–stromal tumour, unclassified. Mixed germ cell–sex cord–stromal tumour, unclassified, showing an admixture of germ cells and sex cord cells (top left and right). Sex cord cells also grow in clustered hollow or solid tubules (centre and bottom).
A: Mixed Germ Cell-Sex Cord-Stromal Tumor, Unclassified
Back Extra: Mixed Germ Cell-Sex Cord-Stromal Tumour, Unclassified
- Clinical: Most tumours occur in infants or children aged < 10 years, and are occasionally associated with isosexual pseudoprecocity.
- Micro: The tumour shows a variable and haphazard admixture of large germ cells with pleomorphic nuclei and ample cytoplasm, and smaller sex cord cells forming cords, trabeculae, or tubules.
- Ancillary: Immunohistochemically, the sex cord elements are typically positive for inhibin, and the germ cells are immunoreactive for PLAP, OCT4, and KIT.
Reference Gallery:
Mixed germ cell–sex cord–stromal tumour, unclassified. Mixed germ cell–sex cord–stromal tumour showing an admixture of germ cell and sex cord components arranged in a haphazard fashion. The germ cells are large, with pleomorphic nuclei and ample cytoplasm, resembling dysgerminoma tumour cells. The smaller sex cord cells surround the germ cells, forming cords or trabeculae.
Mixed germ cell–sex cord–stromal tumour, unclassified. Mixed germ cell–sex cord–stromal tumour, unclassified, showing an admixture of germ cells and sex cord cells (top left and right). Sex cord cells also grow in clustered hollow or solid tubules (centre and bottom).

Q: The characteristic histologic appearance of an Ovarian Fibroma features intersecting fascicles of bland spindle cells interspersed with [...].
Ovarian fibroma. Fascicles of bland spindle cells with hyalinized plaques.
A: hyalinized plaques
Back Extra: Ovarian Fibroma
- Clinical: Ovarian fibromas are often unilateral and can be associated with Meigs syndrome (ascites and pleural effusion).
- Micro: Characterized by intersecting fascicles of bland spindle cells with hyalinized plaques and occasional calcifications.
- Ancillary: Trisomy and/or tetrasomy 12 is frequently found in ovarian fibromas.
Reference Gallery:
Ovarian fibroma. Fascicles of bland spindle cells with hyalinized plaques.
Mitotically active cellular fibroma. Cellular fascicles of mildly atypical spindle cells with mitoses.

Q: The bland spindle cell neoplasm shown in the image is an Ovarian Fibroma, which can present with the classic clinical triad of the tumor, ascites, and pleural effusion known as [...].
Ovarian fibroma. Fascicles of bland spindle cells with hyalinized plaques.
A: Meigs syndrome
Back Extra: Ovarian Fibroma
- Clinical: Ovarian fibromas are often unilateral and can be associated with Meigs syndrome (ascites and pleural effusion).
- Micro: Characterized by intersecting fascicles of bland spindle cells with hyalinized plaques and occasional calcifications.
- Ancillary: Trisomy and/or tetrasomy 12 is frequently found in ovarian fibromas.
Reference Gallery:
Ovarian fibroma. Fascicles of bland spindle cells with hyalinized plaques.
Mitotically active cellular fibroma. Cellular fascicles of mildly atypical spindle cells with mitoses.

Q: In a Leydig cell tumor, microscopic examination often reveals large epithelioid cells with abundant eosinophilic cytoplasm containing characteristic [...].
Leydig cell tumour. The tumour is composed of epithelioid cells with prominent nucleoli, abundant eosinophilic cytoplasm, and fibrinoid material within vessel wall.
Ovarian Leydig cell tumour. The tumour cells have abundant eosinophilic cytoplasm with easily identifiable cytoplasmic Reinke crystals.
A: Reinke crystals
Back Extra: Leydig Cell Tumour
- Clinical: Leydig Cell Tumour usually presents with endocrine manifestations, most commonly androgenic and rarely estrogenic. The average patient age is 58 years.
- Micro: These tumours are well-circumscribed nodular growths of large polyhedral or rounded epithelioid cells with abundant eosinophilic cytoplasm. Cytoplasmic Reinke crystals are often seen.
- Ancillary: Immunohistochemically, Leydig cell tumours are usually positive for sex cord–stromal markers such as inhibin, calretinin, and melan-A.
Reference Gallery:
Leydig cell tumour. The tumour is composed of epithelioid cells with prominent nucleoli, abundant eosinophilic cytoplasm, and fibrinoid material within vessel wall.
Ovarian Leydig cell tumour. The tumour cells have abundant eosinophilic cytoplasm with easily identifiable cytoplasmic Reinke crystals.

Q: A 58-year-old patient presents with androgenic endocrine manifestations. Biopsy reveals a well-circumscribed nodular growth of large polyhedral cells with prominent nucleoli, abundant eosinophilic cytoplasm, and Reinke crystals. This morphology is diagnostic of a [...].
Leydig cell tumour. The tumour is composed of epithelioid cells with prominent nucleoli, abundant eosinophilic cytoplasm, and fibrinoid material within vessel wall.
Ovarian Leydig cell tumour. The tumour cells have abundant eosinophilic cytoplasm with easily identifiable cytoplasmic Reinke crystals.
A: Leydig cell tumor
Back Extra: Leydig Cell Tumour
- Clinical: Leydig Cell Tumour usually presents with endocrine manifestations, most commonly androgenic and rarely estrogenic. The average patient age is 58 years.
- Micro: These tumours are well-circumscribed nodular growths of large polyhedral or rounded epithelioid cells with abundant eosinophilic cytoplasm. Cytoplasmic Reinke crystals are often seen.
- Ancillary: Immunohistochemically, Leydig cell tumours are usually positive for sex cord–stromal markers such as inhibin, calretinin, and melan-A.
Reference Gallery:
Leydig cell tumour. The tumour is composed of epithelioid cells with prominent nucleoli, abundant eosinophilic cytoplasm, and fibrinoid material within vessel wall.
Ovarian Leydig cell tumour. The tumour cells have abundant eosinophilic cytoplasm with easily identifiable cytoplasmic Reinke crystals.

Q: Microscopically, [...] presents as a well-circumscribed, paucicellular tumor featuring spindle to stellate cells with bland nuclei embedded in an abundant myxoid matrix.
Ovarian myxoma. The tumour is paucicellular, with spindle to stellate cells displaying small and bland nuclei. Cells are embedded in an abundant myxoid background. Small capillary vessels are seen at the bottom left.
A: Ovarian Myxoma
Back Extra: Ovarian Myxoma
- Clinical: Ovarian myxomas typically occur in women of reproductive age and present with nonspecific symptoms related to a pelvic/abdominal mass.
- Micro: The tumour is well circumscribed, paucicellular, with an abundant myxoid matrix and spindle to stellate cells with bland nuclei.
- Ancillary: Ovarian myxomas are positive for vimentin and frequently for SMA, but negative for desmin, S100, keratins, and EMA.
Reference Gallery:
Ovarian myxoma. The tumour is paucicellular, with spindle to stellate cells displaying small and bland nuclei. Cells are embedded in an abundant myxoid background. Small capillary vessels are seen at the bottom left.

Q: The classic microscopic architecture of a Sclerosing Stromal Tumour features a [...] appearance, consisting of cellular nodules separated by hypocellular, edematous, or collagenous stroma.
Sclerosing stromal tumour. Cellular pseudolobules are present in an oedematous to collagenous stroma.
A: pseudolobular
Back Extra: Sclerosing Stromal Tumour
- Clinical: Patients typically present with abnormal uterine bleeding or symptoms related to an ovarian mass, but some tumours are incidental findings.
- Micro: Sclerosing stromal tumour has a pseudolobular appearance with cellular nodules separated by a hypocellular oedematous, collagenous, or occasionally myxoid stroma.
- Ancillary: FISH studies have revealed a subpopulation of tumour cells with trisomy 12, and recurrent FHL2-GLI2 fusion genes in 65% of cases.
Reference Gallery:
Sclerosing stromal tumour. Cellular pseudolobules are present in an oedematous to collagenous stroma.
Sclerosing stromal tumour. Cellular lobules are composed of spindled and epithelioid cells with clear to eosinophilic vacuolated cytoplasm; thin and dilated vessels are also present.

Q: The cellular nodules in a Sclerosing Stromal Tumour are typically composed of a mixture of spindled cells and vacuolated [...] cells, often accompanied by prominent thin and dilated blood vessels.
Sclerosing stromal tumour. Cellular lobules are composed of spindled and epithelioid cells with clear to eosinophilic vacuolated cytoplasm; thin and dilated vessels are also present.
A: epithelioid
Back Extra: Sclerosing Stromal Tumour
- Clinical: Patients typically present with abnormal uterine bleeding or symptoms related to an ovarian mass, but some tumours are incidental findings.
- Micro: Sclerosing stromal tumour has a pseudolobular appearance with cellular nodules separated by a hypocellular oedematous, collagenous, or occasionally myxoid stroma.
- Ancillary: FISH studies have revealed a subpopulation of tumour cells with trisomy 12, and recurrent FHL2-GLI2 fusion genes in 65% of cases.
Reference Gallery:
Sclerosing stromal tumour. Cellular pseudolobules are present in an oedematous to collagenous stroma.
Sclerosing stromal tumour. Cellular lobules are composed of spindled and epithelioid cells with clear to eosinophilic vacuolated cytoplasm; thin and dilated vessels are also present.

Q: Histologically, [...] is an ovarian neoplasm characterized by sheets of cells with bland eccentric nuclei and a single large cytoplasmic vacuole (which characteristically lacks mucin, glycogen, or lipid), set in a fibromatous background.
Signet-ring stromal tumour. The tumour cells have bland eccentric nuclei with small nucleoli and abundant clear cytoplasm containing eosinophilic globules.
Signet-ring stromal tumour. Sheets of signet-ring cells are present within a fibromatous background.
A: Signet-ring stromal tumor
Back Extra: Signet-ring stromal tumour
- Clinical: Signet-ring stromal tumours present with symptoms attributable to an ovarian mass, usually without hormonal manifestations, and occur in adults ranging from 21 to 83 years.
- Micro: The tumour consists of signet-ring cells with bland eccentric nuclei and a single large cytoplasmic vacuole, which do not contain mucin, glycogen, or lipid, in a fibromatous stromal background.
- Ancillary: Immunohistochemically, the tumour cells are positive for calretinin, SF1, and SMA, and may show nuclear β-catenin and cyclin D1 expression.
Reference Gallery:
Signet-ring stromal tumour. The tumour cells have bland eccentric nuclei with small nucleoli and abundant clear cytoplasm containing eosinophilic globules.
Signet-ring stromal tumour. Sheets of signet-ring cells are present within a fibromatous background.

Q: Characterized by a diffuse microscopic growth of uniform tumor cells with characteristic pale-gray cytoplasm and indistinct cell membranes, a [...] is an ovarian sex cord-stromal tumor typically presenting in postmenopausal women.
Thecoma. Typical thecoma showing diffuse growth of tumour cells with indistinct cell membranes resulting in a syncytial appearance.
Thecoma. Uniform tumour cells with the characteristic pale-grey cytoplasm.
A: thecoma
Back Extra: Thecoma
- Clinical: Thecomas are typically unilateral and occur predominantly in postmenopausal women, often associated with endometrial proliferative lesions.
- Micro: Thecomas exhibit a diffuse growth pattern with uniform cells having pale-grey cytoplasm, indistinct cell membranes, and occasional hyaline plaques.
- Ancillary: Immunohistochemically, thecomas are positive for inhibin, calretinin, and other sex cord markers.
Reference Gallery:
Thecoma. Typical thecoma showing diffuse growth of tumour cells with indistinct cell membranes resulting in a syncytial appearance.
Thecoma. Uniform tumour cells with the characteristic pale-grey cytoplasm.

Q: Histologically, the uniform tumor cells of a thecoma feature indistinct cell membranes that result in a characteristic [...] appearance.
Thecoma. Typical thecoma showing diffuse growth of tumour cells with indistinct cell membranes resulting in a syncytial appearance.
A: syncytial
Back Extra: Thecoma
- Clinical: Thecomas are typically unilateral and occur predominantly in postmenopausal women, often associated with endometrial proliferative lesions.
- Micro: Thecomas exhibit a diffuse growth pattern with uniform cells having pale-grey cytoplasm, indistinct cell membranes, and occasional hyaline plaques.
- Ancillary: Immunohistochemically, thecomas are positive for inhibin, calretinin, and other sex cord markers.
Reference Gallery:
Thecoma. Typical thecoma showing diffuse growth of tumour cells with indistinct cell membranes resulting in a syncytial appearance.
Thecoma. Uniform tumour cells with the characteristic pale-grey cytoplasm.

Q: Microscopically, Gonadoblastoma features discrete nests composed of large, clear germ cells and smaller, dark [...] arranged around deposits of basement membrane material (often with calcifications).
Gonadoblastoma. Classic pattern of gonadoblastoma with discrete nests consisting of small, dark, sex cord cells; germ cells with clear cytoplasm; and round deposits of basement membrane material. One nest (bottom right) contains a calcification.
Gonadoblastoma. The sex cord cells form a partial palisade at the periphery of a nest and are also arranged around basement membrane deposits and germ cells.
A: sex cord cells
Back Extra: Gonadoblastoma
- Clinical: Gonadoblastoma is often found in patients with disorders of sex development, typically presenting with ambiguous genitalia or primary amenorrhoea.
- Micro: The classic pattern of gonadoblastoma includes discrete nests of germ cells, sex cord cells, and basement membrane deposits, often with calcifications.
- Ancillary: Immunohistochemical staining shows germ cells positive for OCT3/4, podoplanin, and PLAP, while sex cord cells are positive for inhibin, calretinin, SF1, FOXL2, and SOX9.
Reference Gallery:
Gonadoblastoma with germinoma. Gonadoblastoma shows a variegated, pink to tan to white granular cut surface (top) and is associated with a solid white area (bottom) corresponding to a germinoma.
Gonadoblastoma. Classic pattern of gonadoblastoma with discrete nests consisting of small, dark, sex cord cells; germ cells with clear cytoplasm; and round deposits of basement membrane material. One nest (bottom right) contains a calcification.
Gonadoblastoma. The sex cord cells form a partial palisade at the periphery of a nest and are also arranged around basement membrane deposits and germ cells.
Gonadoblastoma. Burnt-out gonadoblastoma consisting of islands of irregular and mulberry-shaped calcifications devoid of tumour cells in a cellular stroma.
Gonadoblastoma. Large confluent nests of gonadoblastoma closely resemble germinoma at low power. Classic gonadoblastoma nests are seen at the top-right corner.
Gonadoblastoma. Immunostaining for SF1 highlights the consistent sex cord component in the tumour shown in <<#9942>>Fig. #9942.
Gonadoblastoma. Cords and small nests (called dissecting gonadoblastoma or, alternatively, undifferentiated gonadal tissue) resemble a common pattern of germinoma.
Gonadoblastoma and germinoma. Gonadoblastoma with admixed germinoma.
Gonadoblastoma and germinoma. Inhibin staining highlights the sex cord component in the nests of gonadoblastoma and the lack thereof in the germinoma.
Gonadoblastoma. The germ cells of gonadoblastoma are variably positive for OCT3/4.
Gonadoblastoma. An inhibin immunostain highlights the sex cord cells within small nests and ill-defined cords of undifferentiated gonadal tissue or dissecting gonadoblastoma.

Q: Immunohistochemical evaluation of Gonadoblastoma highlights its dual cell populations, with the sex cord cells characteristically staining positive for SF1 and [...], while the germ cells stain positive for OCT3/4.
Gonadoblastoma. Immunostaining for SF1 highlights the consistent sex cord component in the tumour shown in <<#9942>>Fig. #9942.
Gonadoblastoma and germinoma. Inhibin staining highlights the sex cord component in the nests of gonadoblastoma and the lack thereof in the germinoma.
Gonadoblastoma. The germ cells of gonadoblastoma are variably positive for OCT3/4.
A: inhibin
Back Extra: Gonadoblastoma
- Clinical: Gonadoblastoma is often found in patients with disorders of sex development, typically presenting with ambiguous genitalia or primary amenorrhoea.
- Micro: The classic pattern of gonadoblastoma includes discrete nests of germ cells, sex cord cells, and basement membrane deposits, often with calcifications.
- Ancillary: Immunohistochemical staining shows germ cells positive for OCT3/4, podoplanin, and PLAP, while sex cord cells are positive for inhibin, calretinin, SF1, FOXL2, and SOX9.
Reference Gallery:
Gonadoblastoma with germinoma. Gonadoblastoma shows a variegated, pink to tan to white granular cut surface (top) and is associated with a solid white area (bottom) corresponding to a germinoma.
Gonadoblastoma. Classic pattern of gonadoblastoma with discrete nests consisting of small, dark, sex cord cells; germ cells with clear cytoplasm; and round deposits of basement membrane material. One nest (bottom right) contains a calcification.
Gonadoblastoma. The sex cord cells form a partial palisade at the periphery of a nest and are also arranged around basement membrane deposits and germ cells.
Gonadoblastoma. Burnt-out gonadoblastoma consisting of islands of irregular and mulberry-shaped calcifications devoid of tumour cells in a cellular stroma.
Gonadoblastoma. Large confluent nests of gonadoblastoma closely resemble germinoma at low power. Classic gonadoblastoma nests are seen at the top-right corner.
Gonadoblastoma. Immunostaining for SF1 highlights the consistent sex cord component in the tumour shown in <<#9942>>Fig. #9942.
Gonadoblastoma. Cords and small nests (called dissecting gonadoblastoma or, alternatively, undifferentiated gonadal tissue) resemble a common pattern of germinoma.
Gonadoblastoma and germinoma. Gonadoblastoma with admixed germinoma.
Gonadoblastoma and germinoma. Inhibin staining highlights the sex cord component in the nests of gonadoblastoma and the lack thereof in the germinoma.
Gonadoblastoma. The germ cells of gonadoblastoma are variably positive for OCT3/4.
Gonadoblastoma. An inhibin immunostain highlights the sex cord cells within small nests and ill-defined cords of undifferentiated gonadal tissue or dissecting gonadoblastoma.

Q: A "burnt-out" Gonadoblastoma typically lacks viable tumor cells and instead consists entirely of islands of irregular, mulberry-shaped [...] within a cellular stroma.
Gonadoblastoma. Burnt-out gonadoblastoma consisting of islands of irregular and mulberry-shaped calcifications devoid of tumour cells in a cellular stroma.
A: calcifications
Back Extra: Gonadoblastoma
- Clinical: Gonadoblastoma is often found in patients with disorders of sex development, typically presenting with ambiguous genitalia or primary amenorrhoea.
- Micro: The classic pattern of gonadoblastoma includes discrete nests of germ cells, sex cord cells, and basement membrane deposits, often with calcifications.
- Ancillary: Immunohistochemical staining shows germ cells positive for OCT3/4, podoplanin, and PLAP, while sex cord cells are positive for inhibin, calretinin, SF1, FOXL2, and SOX9.
Reference Gallery:
Gonadoblastoma with germinoma. Gonadoblastoma shows a variegated, pink to tan to white granular cut surface (top) and is associated with a solid white area (bottom) corresponding to a germinoma.
Gonadoblastoma. Classic pattern of gonadoblastoma with discrete nests consisting of small, dark, sex cord cells; germ cells with clear cytoplasm; and round deposits of basement membrane material. One nest (bottom right) contains a calcification.
Gonadoblastoma. The sex cord cells form a partial palisade at the periphery of a nest and are also arranged around basement membrane deposits and germ cells.
Gonadoblastoma. Burnt-out gonadoblastoma consisting of islands of irregular and mulberry-shaped calcifications devoid of tumour cells in a cellular stroma.
Gonadoblastoma. Large confluent nests of gonadoblastoma closely resemble germinoma at low power. Classic gonadoblastoma nests are seen at the top-right corner.
Gonadoblastoma. Immunostaining for SF1 highlights the consistent sex cord component in the tumour shown in <<#9942>>Fig. #9942.
Gonadoblastoma. Cords and small nests (called dissecting gonadoblastoma or, alternatively, undifferentiated gonadal tissue) resemble a common pattern of germinoma.
Gonadoblastoma and germinoma. Gonadoblastoma with admixed germinoma.
Gonadoblastoma and germinoma. Inhibin staining highlights the sex cord component in the nests of gonadoblastoma and the lack thereof in the germinoma.
Gonadoblastoma. The germ cells of gonadoblastoma are variably positive for OCT3/4.
Gonadoblastoma. An inhibin immunostain highlights the sex cord cells within small nests and ill-defined cords of undifferentiated gonadal tissue or dissecting gonadoblastoma.

Q: Morphologically, gynandroblastoma is a biphasic sex cord-stromal tumor characterized by an admixture of male elements (Sertoli or Sertoli-Leydig cell tumor) and female elements, predominantly [...] (adult or juvenile).
Gynandroblastoma composed of Sertoli–Leydig cell tumour (left) and adult granulosa cell tumour (right)
A: granulosa cell tumor
Back Extra: Gynandroblastoma
- Clinical: Patients with gynandroblastoma can present with abdominal pain, distension, and androgenic or estrogenic symptoms.
- Micro: These tumours comprise a mixture of female elements (adult or juvenile granulosa cell tumour) and male elements (Sertoli cell tumour or Sertoli–Leydig cell tumour).
- Ancillary: Gynandroblastomas often show heterozygous hotspot mutations in the RNase IIIb domain of DICER1, especially in cases with juvenile granulosa cell tumour and Sertoli–Leydig cell tumour components.
Reference Gallery:
Gynandroblastoma composed of Sertoli–Leydig cell tumour (left) and adult granulosa cell tumour (right)
Gynandroblastoma. Gynandroblastoma composed of juvenile granulosa cell tumour (shown here) and moderately differentiated Sertoli–Leydig cell tumour with heterologous intestinal mucinous differentiation (shown in Fig. 13773).
Gynandroblastoma. Gynandroblastoma composed of juvenile granulosa cell tumour (shown in Fig. 13772) and moderately differentiated Sertoli–Leydig cell tumour with heterologous intestinal mucinous differentiation (shown here).
Gynandroblastoma. Gynandroblastoma composed of adult granulosa cell tumour (shown here) and well-differentiated Sertoli–Leydig cell tumour (shown in Fig. 13775).
Gynandroblastoma. Gynandroblastoma composed of adult granulosa cell tumour (shown in Fig. 13774) and well-differentiated Sertoli–Leydig cell tumour (shown here).

Q: Molecular analysis of gynandroblastoma, especially in cases containing both juvenile granulosa cell and Sertoli-Leydig cell tumor components, frequently reveals heterozygous hotspot mutations in the RNase IIIb domain of [...].
Gynandroblastoma. Gynandroblastoma composed of juvenile granulosa cell tumour (shown here) and moderately differentiated Sertoli–Leydig cell tumour with heterologous intestinal mucinous differentiation (shown in Fig. 13773).
Gynandroblastoma. Gynandroblastoma composed of juvenile granulosa cell tumour (shown in Fig. 13772) and moderately differentiated Sertoli–Leydig cell tumour with heterologous intestinal mucinous differentiation (shown here).
A: DICER1
Back Extra: Gynandroblastoma
- Clinical: Patients with gynandroblastoma can present with abdominal pain, distension, and androgenic or estrogenic symptoms.
- Micro: These tumours comprise a mixture of female elements (adult or juvenile granulosa cell tumour) and male elements (Sertoli cell tumour or Sertoli–Leydig cell tumour).
- Ancillary: Gynandroblastomas often show heterozygous hotspot mutations in the RNase IIIb domain of DICER1, especially in cases with juvenile granulosa cell tumour and Sertoli–Leydig cell tumour components.
Reference Gallery:
Gynandroblastoma composed of Sertoli–Leydig cell tumour (left) and adult granulosa cell tumour (right)
Gynandroblastoma. Gynandroblastoma composed of juvenile granulosa cell tumour (shown here) and moderately differentiated Sertoli–Leydig cell tumour with heterologous intestinal mucinous differentiation (shown in Fig. 13773).
Gynandroblastoma. Gynandroblastoma composed of juvenile granulosa cell tumour (shown in Fig. 13772) and moderately differentiated Sertoli–Leydig cell tumour with heterologous intestinal mucinous differentiation (shown here).
Gynandroblastoma. Gynandroblastoma composed of adult granulosa cell tumour (shown here) and well-differentiated Sertoli–Leydig cell tumour (shown in Fig. 13775).
Gynandroblastoma. Gynandroblastoma composed of adult granulosa cell tumour (shown in Fig. 13774) and well-differentiated Sertoli–Leydig cell tumour (shown here).

Q: Histologically, a Microcystic Stromal Tumor characteristically exhibits a classic triad of solid cellular zones, coalescing microcysts, and intersecting bands of hyalinized [...].
Microcystic stromal tumour. Cellular islands with coalescing microcysts intersected by bands of hyalinized stroma.
Microcystic stromal tumour. Rounded microcysts and ovoid cells with intracytoplasmic vacuoles merge with the solid cellular component (upper left).
A: fibrous stroma
Back Extra: Microcystic Stromal Tumour
- Clinical: Most patients present with symptoms related to a pelvic mass. Hormonal manifestations are usually absent. Patients have ranged in age from 23 to 71 years (mean: 45 years). The tumour may rarely occur as an extracolonic m…
- Micro: Most tumours exhibit a classic triad of microcysts, solid cellular zones, and fibrous stroma, which vary in proportion. Microcysts are composed of small rounded to oval cystic spaces, in areas coalescing to larger irregu…
- Cyto: Not clinically relevant
- Ancillary: Tumour cells are usually diffusely positive for β-catenin (nuclear and cytoplasmic), CD10, WT1, FOXL2, cyclin D1, and SF1, while inhibin, calretinin, and EMA are typically negative. Tumours may be positive for AR but are…
Reference Gallery:
Microcystic stromal tumour. Cellular islands with coalescing microcysts intersected by bands of hyalinized stroma.
Microcystic stromal tumour. Rounded microcysts and ovoid cells with intracytoplasmic vacuoles merge with the solid cellular component (upper left).
Microcystic stromal tumour. There is diffuse nuclear and cytoplasmic β-catenin immunoreactivity.
Microcystic stromal tumour. Diffuse nuclear staining with cyclin D1.

Q: In Microcystic Stromal Tumor, immunohistochemistry characteristically demonstrates diffuse nuclear and cytoplasmic expression of [...].
Microcystic stromal tumour. There is diffuse nuclear and cytoplasmic β-catenin immunoreactivity.
A: β-catenin
Back Extra: Microcystic Stromal Tumour
- Clinical: Most patients present with symptoms related to a pelvic mass. Hormonal manifestations are usually absent. Patients have ranged in age from 23 to 71 years (mean: 45 years). The tumour may rarely occur as an extracolonic m…
- Micro: Most tumours exhibit a classic triad of microcysts, solid cellular zones, and fibrous stroma, which vary in proportion. Microcysts are composed of small rounded to oval cystic spaces, in areas coalescing to larger irregu…
- Cyto: Not clinically relevant
- Ancillary: Tumour cells are usually diffusely positive for β-catenin (nuclear and cytoplasmic), CD10, WT1, FOXL2, cyclin D1, and SF1, while inhibin, calretinin, and EMA are typically negative. Tumours may be positive for AR but are…
Reference Gallery:
Microcystic stromal tumour. Cellular islands with coalescing microcysts intersected by bands of hyalinized stroma.
Microcystic stromal tumour. Rounded microcysts and ovoid cells with intracytoplasmic vacuoles merge with the solid cellular component (upper left).
Microcystic stromal tumour. There is diffuse nuclear and cytoplasmic β-catenin immunoreactivity.
Microcystic stromal tumour. Diffuse nuclear staining with cyclin D1.

Q: In Microcystic Stromal Tumor, in addition to β-catenin, the tumor cells typically show diffuse nuclear immunoreactivity for [...].
Microcystic stromal tumour. Diffuse nuclear staining with cyclin D1.
A: cyclin D1
Back Extra: Microcystic Stromal Tumour
- Clinical: Most patients present with symptoms related to a pelvic mass. Hormonal manifestations are usually absent. Patients have ranged in age from 23 to 71 years (mean: 45 years). The tumour may rarely occur as an extracolonic m…
- Micro: Most tumours exhibit a classic triad of microcysts, solid cellular zones, and fibrous stroma, which vary in proportion. Microcysts are composed of small rounded to oval cystic spaces, in areas coalescing to larger irregu…
- Cyto: Not clinically relevant
- Ancillary: Tumour cells are usually diffusely positive for β-catenin (nuclear and cytoplasmic), CD10, WT1, FOXL2, cyclin D1, and SF1, while inhibin, calretinin, and EMA are typically negative. Tumours may be positive for AR but are…
Reference Gallery:
Microcystic stromal tumour. Cellular islands with coalescing microcysts intersected by bands of hyalinized stroma.
Microcystic stromal tumour. Rounded microcysts and ovoid cells with intracytoplasmic vacuoles merge with the solid cellular component (upper left).
Microcystic stromal tumour. There is diffuse nuclear and cytoplasmic β-catenin immunoreactivity.
Microcystic stromal tumour. Diffuse nuclear staining with cyclin D1.

Q: A hallmark histologic pattern of a Sertoli Cell Tumor is the presence of tightly packed or elongated [...] and cords lined by bland cells with pale or eosinophilic cytoplasm.
Sertoli cell tumour. Tubules and cords contain tumour cells with pale cytoplasm. The small to medium-sized nuclei are round to oval and bland.
Sertoli cell tumour. The tumour shows small, round to elongated tubules lined by cuboidal cells with scant eosinophilic cytoplasm separated by minimal collagenous stroma.
A: tubules
Back Extra: Sertoli Cell Tumour
- Clinical: Sertoli cell tumours can present with signs or symptoms related to a pelvic mass, estrogenic or androgenic manifestations, or may be an incidental finding. A subset of patients have Peutz–Jeghers syndrome.
- Micro: Sertoli cell tumours show a variety of patterns, including tubules, trabecular, diffuse, alveolar, pseudopapillary, retiform, and (rarely) pseudoendometrioid and spindled. Cells have pale, sometimes lipid-rich to eosinophilic cytoplasm and bland nuclei.
- Ancillary: Most Sertoli cell tumours are positive for inhibin, SF1, calretinin, CD99, WT1, and broad-spectrum cytokeratins. DICER1 mutations may be present.
Reference Gallery:
Sertoli cell tumour. Tubules and cords contain tumour cells with pale cytoplasm. The small to medium-sized nuclei are round to oval and bland.
Sertoli cell tumour, lipid-rich. The tumour is composed of tightly packed tubules with abundant pale (lipid-rich) cytoplasm and basally located small and round nuclei with bland cytological features.
Sertoli cell tumour. The tumour shows small, round to elongated tubules lined by cuboidal cells with scant eosinophilic cytoplasm separated by minimal collagenous stroma.

Q: A specific morphologic variant of Sertoli Cell Tumor features tightly packed tubules lined by cells with abundant, pale [...] cytoplasm and basally located, round, bland nuclei.
Sertoli cell tumour, lipid-rich. The tumour is composed of tightly packed tubules with abundant pale (lipid-rich) cytoplasm and basally located small and round nuclei with bland cytological features.
A: lipid-rich
Back Extra: Sertoli Cell Tumour
- Clinical: Sertoli cell tumours can present with signs or symptoms related to a pelvic mass, estrogenic or androgenic manifestations, or may be an incidental finding. A subset of patients have Peutz–Jeghers syndrome.
- Micro: Sertoli cell tumours show a variety of patterns, including tubules, trabecular, diffuse, alveolar, pseudopapillary, retiform, and (rarely) pseudoendometrioid and spindled. Cells have pale, sometimes lipid-rich to eosinophilic cytoplasm and bland nuclei.
- Ancillary: Most Sertoli cell tumours are positive for inhibin, SF1, calretinin, CD99, WT1, and broad-spectrum cytokeratins. DICER1 mutations may be present.
Reference Gallery:
Sertoli cell tumour. Tubules and cords contain tumour cells with pale cytoplasm. The small to medium-sized nuclei are round to oval and bland.
Sertoli cell tumour, lipid-rich. The tumour is composed of tightly packed tubules with abundant pale (lipid-rich) cytoplasm and basally located small and round nuclei with bland cytological features.
Sertoli cell tumour. The tumour shows small, round to elongated tubules lined by cuboidal cells with scant eosinophilic cytoplasm separated by minimal collagenous stroma.

Q: This sex cord-stromal neoplasm often presents with androgenic or estrogenic manifestations and classically forms tubules and cords. A subset of patients have Peutz-Jeghers syndrome. Diagnosis: [...].
Sertoli cell tumour. Tubules and cords contain tumour cells with pale cytoplasm. The small to medium-sized nuclei are round to oval and bland.
Sertoli cell tumour, lipid-rich. The tumour is composed of tightly packed tubules with abundant pale (lipid-rich) cytoplasm and basally located small and round nuclei with bland cytological features.
Sertoli cell tumour. The tumour shows small, round to elongated tubules lined by cuboidal cells with scant eosinophilic cytoplasm separated by minimal collagenous stroma.
A: Sertoli Cell Tumor
Back Extra: Sertoli Cell Tumour
- Clinical: Sertoli cell tumours can present with signs or symptoms related to a pelvic mass, estrogenic or androgenic manifestations, or may be an incidental finding. A subset of patients have Peutz–Jeghers syndrome.
- Micro: Sertoli cell tumours show a variety of patterns, including tubules, trabecular, diffuse, alveolar, pseudopapillary, retiform, and (rarely) pseudoendometrioid and spindled. Cells have pale, sometimes lipid-rich to eosinophilic cytoplasm and bland nuclei.
- Ancillary: Most Sertoli cell tumours are positive for inhibin, SF1, calretinin, CD99, WT1, and broad-spectrum cytokeratins. DICER1 mutations may be present.
Reference Gallery:
Sertoli cell tumour. Tubules and cords contain tumour cells with pale cytoplasm. The small to medium-sized nuclei are round to oval and bland.
Sertoli cell tumour, lipid-rich. The tumour is composed of tightly packed tubules with abundant pale (lipid-rich) cytoplasm and basally located small and round nuclei with bland cytological features.
Sertoli cell tumour. The tumour shows small, round to elongated tubules lined by cuboidal cells with scant eosinophilic cytoplasm separated by minimal collagenous stroma.

Q: Microscopically, a well-differentiated Sertoli-Leydig cell tumor is characterized by open or closed tubules of Sertoli cells admixed with clusters of eosinophilic [...] cells.
Sertoli–Leydig cell tumour. Well-differentiated Sertoli–Leydig cell tumour, with open sertoliform tubules and Leydig cell clusters between tubules.
A: Leydig
Back Extra: Sertoli-Leydig Cell Tumour
- Clinical: Sertoli-Leydig Cell Tumours can present with androgenic manifestations in 40-60% of patients, or estrogenic manifestations in rare cases, and may also present with abdominal pain, ascites, or tumour rupture.
- Micro: Well-differentiated Sertoli-Leydig Cell Tumours are characterized by open or closed tubules of Sertoli cells and clusters of Leydig cells, while poorly differentiated forms show a sarcomatoid stroma and conspicuous mitotic figures.
- Ancillary: Sertoli cells are typically positive for vimentin, pancytokeratin, and sex cord markers (α-inhibin, calretinin, SF1, WT1, FOXL2), while Leydig cells usually express α-inhibin and melan-A.
Reference Gallery:
Sertoli–Leydig cell tumour. Well-differentiated Sertoli–Leydig cell tumour, with open sertoliform tubules and Leydig cell clusters between tubules.
Sertoli–Leydig cell tumour. Moderately differentiated Sertoli–Leydig cell tumour, with irregular anastomosing cords and closed sertoliform tubules admixed with plump eosinophilic Leydig cells. This tumour harbours hotspot mutations in the RNase IIIb domain of DICER1.
Sertoli–Leydig cell tumour. Poorly differentiated Sertoli–Leydig cell tumour, with storiform arrangement of primitive gonadal stromal cells and rare individual Leydig cells. Other areas of this tumour showed closed sertoliform tubules and Leydig cells. This tumour harbours hotspot mutations in the RNase IIIb domain of DICER1.
Sertoli–Leydig cell tumour. Heterologous intestinal mucinous differentiation in a moderately differentiated tumour. This tumour harbours hotspot mutations in the RNase IIIb domain of DICER1.
Sertoli–Leydig cell tumour. Retiform differentiation in a moderately differentiated tumour. This tumour harbours hotspot mutations in the RNase IIIb domain of DICER1.
Sertoli–Leydig cell tumour. FOXL2 immunohistochemistry showing staining of the sertoliform component and no staining of the Leydig cells, in a well-differentiated Sertoli–Leydig cell tumour.
Sertoli–Leydig cell tumour. Cellular areas alternate with hypocellular areas in this intermediate-grade Sertoli–Leydig cell tumour, imparting a multinodular appearance on low-power examination.

Q: Moderately and poorly differentiated variants of Sertoli-Leydig cell tumor, including those with heterologous or retiform differentiation, frequently harbor hotspot mutations in the RNase IIIb domain of [...].
Sertoli–Leydig cell tumour. Moderately differentiated Sertoli–Leydig cell tumour, with irregular anastomosing cords and closed sertoliform tubules admixed with plump eosinophilic Leydig cells. This tumour harbours hotspot mutations in the RNase IIIb domain of DICER1.
Sertoli–Leydig cell tumour. Poorly differentiated Sertoli–Leydig cell tumour, with storiform arrangement of primitive gonadal stromal cells and rare individual Leydig cells. Other areas of this tumour showed closed sertoliform tubules and Leydig cells. This tumour harbours hotspot mutations in the RNase IIIb domain of DICER1.
Sertoli–Leydig cell tumour. Heterologous intestinal mucinous differentiation in a moderately differentiated tumour. This tumour harbours hotspot mutations in the RNase IIIb domain of DICER1.
A: DICER1
Back Extra: Sertoli-Leydig Cell Tumour
- Clinical: Sertoli-Leydig Cell Tumours can present with androgenic manifestations in 40-60% of patients, or estrogenic manifestations in rare cases, and may also present with abdominal pain, ascites, or tumour rupture.
- Micro: Well-differentiated Sertoli-Leydig Cell Tumours are characterized by open or closed tubules of Sertoli cells and clusters of Leydig cells, while poorly differentiated forms show a sarcomatoid stroma and conspicuous mitotic figures.
- Ancillary: Sertoli cells are typically positive for vimentin, pancytokeratin, and sex cord markers (α-inhibin, calretinin, SF1, WT1, FOXL2), while Leydig cells usually express α-inhibin and melan-A.
Reference Gallery:
Sertoli–Leydig cell tumour. Well-differentiated Sertoli–Leydig cell tumour, with open sertoliform tubules and Leydig cell clusters between tubules.
Sertoli–Leydig cell tumour. Moderately differentiated Sertoli–Leydig cell tumour, with irregular anastomosing cords and closed sertoliform tubules admixed with plump eosinophilic Leydig cells. This tumour harbours hotspot mutations in the RNase IIIb domain of DICER1.
Sertoli–Leydig cell tumour. Poorly differentiated Sertoli–Leydig cell tumour, with storiform arrangement of primitive gonadal stromal cells and rare individual Leydig cells. Other areas of this tumour showed closed sertoliform tubules and Leydig cells. This tumour harbours hotspot mutations in the RNase IIIb domain of DICER1.
Sertoli–Leydig cell tumour. Heterologous intestinal mucinous differentiation in a moderately differentiated tumour. This tumour harbours hotspot mutations in the RNase IIIb domain of DICER1.
Sertoli–Leydig cell tumour. Retiform differentiation in a moderately differentiated tumour. This tumour harbours hotspot mutations in the RNase IIIb domain of DICER1.
Sertoli–Leydig cell tumour. FOXL2 immunohistochemistry showing staining of the sertoliform component and no staining of the Leydig cells, in a well-differentiated Sertoli–Leydig cell tumour.
Sertoli–Leydig cell tumour. Cellular areas alternate with hypocellular areas in this intermediate-grade Sertoli–Leydig cell tumour, imparting a multinodular appearance on low-power examination.

Q: In a Sertoli-Leydig cell tumor, immunohistochemistry for FOXL2 characteristically highlights the [...] cell component while remaining negative in the Leydig cells.
Sertoli–Leydig cell tumour. FOXL2 immunohistochemistry showing staining of the sertoliform component and no staining of the Leydig cells, in a well-differentiated Sertoli–Leydig cell tumour.
A: Sertoli
Back Extra: Sertoli-Leydig Cell Tumour
- Clinical: Sertoli-Leydig Cell Tumours can present with androgenic manifestations in 40-60% of patients, or estrogenic manifestations in rare cases, and may also present with abdominal pain, ascites, or tumour rupture.
- Micro: Well-differentiated Sertoli-Leydig Cell Tumours are characterized by open or closed tubules of Sertoli cells and clusters of Leydig cells, while poorly differentiated forms show a sarcomatoid stroma and conspicuous mitotic figures.
- Ancillary: Sertoli cells are typically positive for vimentin, pancytokeratin, and sex cord markers (α-inhibin, calretinin, SF1, WT1, FOXL2), while Leydig cells usually express α-inhibin and melan-A.
Reference Gallery:
Sertoli–Leydig cell tumour. Well-differentiated Sertoli–Leydig cell tumour, with open sertoliform tubules and Leydig cell clusters between tubules.
Sertoli–Leydig cell tumour. Moderately differentiated Sertoli–Leydig cell tumour, with irregular anastomosing cords and closed sertoliform tubules admixed with plump eosinophilic Leydig cells. This tumour harbours hotspot mutations in the RNase IIIb domain of DICER1.
Sertoli–Leydig cell tumour. Poorly differentiated Sertoli–Leydig cell tumour, with storiform arrangement of primitive gonadal stromal cells and rare individual Leydig cells. Other areas of this tumour showed closed sertoliform tubules and Leydig cells. This tumour harbours hotspot mutations in the RNase IIIb domain of DICER1.
Sertoli–Leydig cell tumour. Heterologous intestinal mucinous differentiation in a moderately differentiated tumour. This tumour harbours hotspot mutations in the RNase IIIb domain of DICER1.
Sertoli–Leydig cell tumour. Retiform differentiation in a moderately differentiated tumour. This tumour harbours hotspot mutations in the RNase IIIb domain of DICER1.
Sertoli–Leydig cell tumour. FOXL2 immunohistochemistry showing staining of the sertoliform component and no staining of the Leydig cells, in a well-differentiated Sertoli–Leydig cell tumour.
Sertoli–Leydig cell tumour. Cellular areas alternate with hypocellular areas in this intermediate-grade Sertoli–Leydig cell tumour, imparting a multinodular appearance on low-power examination.

Q: Sex cord tumor with annular tubules is a distinct ovarian neoplasm that may occur sporadically or as an incidental finding in patients with [...].
Sex cord tumour with annular tubules. Discrete small nests with a conspicuous tubular pattern and typical basement membrane–like material in a patient with Peutz–Jeghers syndrome.
A: Peutz-Jeghers syndrome
Back Extra: Sex cord tumour with annular tubules
- Clinical: These lesions may be seen at any age and typically represent an incidental finding in patients with Peutz–Jeghers syndrome; non-syndromic cases may be associated with nonspecific symptoms and signs.
- Micro: Characterized by variably sized, usually rounded nests composed of simple or complex tubules that encircle hyaline basement membrane–like material, with tall cells and basally located round nuclei displaying an antipodal distribution within the tubules.
- Ancillary: The tumour cells are typically positive for calretinin, WT1, inhibin, SF1, FOXL2, and CD56, and are typically negative for EMA and CD10.
Reference Gallery:
Sex cord tumour with annular tubules. Large nests with central cystic change, showing characteristic tubules at the periphery, most of which encircle hyaline material (not associated with Peutz–Jeghers syndrome).
Sex cord tumour with annular tubules. Discrete small nests with a conspicuous tubular pattern and typical basement membrane–like material in a patient with Peutz–Jeghers syndrome.

Q: The characteristic histologic feature of a Sex cord tumor with annular tubules consists of variably sized nests of simple or complex tubules that encircle [...] material.
Sex cord tumour with annular tubules. Large nests with central cystic change, showing characteristic tubules at the periphery, most of which encircle hyaline material (not associated with Peutz–Jeghers syndrome).
Sex cord tumour with annular tubules. Discrete small nests with a conspicuous tubular pattern and typical basement membrane–like material in a patient with Peutz–Jeghers syndrome.
A: hyaline basement membrane-like
Back Extra: Sex cord tumour with annular tubules
- Clinical: These lesions may be seen at any age and typically represent an incidental finding in patients with Peutz–Jeghers syndrome; non-syndromic cases may be associated with nonspecific symptoms and signs.
- Micro: Characterized by variably sized, usually rounded nests composed of simple or complex tubules that encircle hyaline basement membrane–like material, with tall cells and basally located round nuclei displaying an antipodal distribution within the tubules.
- Ancillary: The tumour cells are typically positive for calretinin, WT1, inhibin, SF1, FOXL2, and CD56, and are typically negative for EMA and CD10.
Reference Gallery:
Sex cord tumour with annular tubules. Large nests with central cystic change, showing characteristic tubules at the periphery, most of which encircle hyaline material (not associated with Peutz–Jeghers syndrome).
Sex cord tumour with annular tubules. Discrete small nests with a conspicuous tubular pattern and typical basement membrane–like material in a patient with Peutz–Jeghers syndrome.

Q: The most common architectural pattern in an Adult Granulosa Cell Tumor is the microfollicular growth pattern, which is characterized by monotonous cells with nuclear grooves arranged around hyalinized spaces known as [...].
Adult granulosa cell tumour. Microfollicular growth pattern (Call–Exner bodies) composed of monotonous tumour cells with nuclear grooves and folds and scant cytoplasm disposed around spaces filled with hyalinized material.
A: Call-Exner bodies
Back Extra: Adult Granulosa Cell Tumour
- Clinical: Adult Granulosa Cell Tumours are most common in perimenopausal women and often present with abdominal pain or estrogenic manifestations, such as uterine bleeding.
- Micro: The most common architectural pattern is the microfollicular growth pattern with Call–Exner bodies, but other patterns like insular, macrofollicular, and trabecular can also be seen.
- Ancillary: Tumours are typically positive for FOXL2, calretinin, and inhibin, and the characteristic FOXL2 point mutation can be helpful in diagnosis.
Reference Gallery:
Adult granulosa cell tumour. Microfollicular growth pattern (Call–Exner bodies) composed of monotonous tumour cells with nuclear grooves and folds and scant cytoplasm disposed around spaces filled with hyalinized material.
Adult granulosa cell tumour. Insular growth pattern.
Adult granulosa cell tumour. Macrofollicular growth pattern.
Adult granulosa cell tumour. Trabecular growth pattern.
Adult granulosa cell tumour. Fibroma-like growth.
Adult granulosa cell tumour. The tumour has a nodular appearance, with extensive areas of haemorrhage and necrosis. The nodules have a yellow and soft cut surface.
Adult granulosa cell tumour. Reticulin fibres surround groups of granulosa cells, unlike in fibroma, where reticulin fibres are present around individual cells.
Adult granulosa cell tumour. A solid and cystic, tan/cream tumour with serosanguinous fluid.

Q: An Adult Granulosa Cell Tumor is a sex cord-stromal neoplasm that often presents with abnormal uterine bleeding due to [...] manifestations, and grossly appears as a solid and cystic mass with a characteristic yellow cut surface.
Adult granulosa cell tumour. The tumour has a nodular appearance, with extensive areas of haemorrhage and necrosis. The nodules have a yellow and soft cut surface.
Adult granulosa cell tumour. A solid and cystic, tan/cream tumour with serosanguinous fluid.
A: estrogenic
Back Extra: Adult Granulosa Cell Tumour
- Clinical: Adult Granulosa Cell Tumours are most common in perimenopausal women and often present with abdominal pain or estrogenic manifestations, such as uterine bleeding.
- Micro: The most common architectural pattern is the microfollicular growth pattern with Call–Exner bodies, but other patterns like insular, macrofollicular, and trabecular can also be seen.
- Ancillary: Tumours are typically positive for FOXL2, calretinin, and inhibin, and the characteristic FOXL2 point mutation can be helpful in diagnosis.
Reference Gallery:
Adult granulosa cell tumour. Microfollicular growth pattern (Call–Exner bodies) composed of monotonous tumour cells with nuclear grooves and folds and scant cytoplasm disposed around spaces filled with hyalinized material.
Adult granulosa cell tumour. Insular growth pattern.
Adult granulosa cell tumour. Macrofollicular growth pattern.
Adult granulosa cell tumour. Trabecular growth pattern.
Adult granulosa cell tumour. Fibroma-like growth.
Adult granulosa cell tumour. The tumour has a nodular appearance, with extensive areas of haemorrhage and necrosis. The nodules have a yellow and soft cut surface.
Adult granulosa cell tumour. Reticulin fibres surround groups of granulosa cells, unlike in fibroma, where reticulin fibres are present around individual cells.
Adult granulosa cell tumour. A solid and cystic, tan/cream tumour with serosanguinous fluid.

Q: To help distinguish an Adult Granulosa Cell Tumor from a cellular fibroma, a reticulin stain can be utilized; in granulosa cell tumors, the reticulin fibers characteristically surround [...] rather than individual tumor cells.
Adult granulosa cell tumour. Reticulin fibres surround groups of granulosa cells, unlike in fibroma, where reticulin fibres are present around individual cells.
A: groups of cells
Back Extra: Adult Granulosa Cell Tumour
- Clinical: Adult Granulosa Cell Tumours are most common in perimenopausal women and often present with abdominal pain or estrogenic manifestations, such as uterine bleeding.
- Micro: The most common architectural pattern is the microfollicular growth pattern with Call–Exner bodies, but other patterns like insular, macrofollicular, and trabecular can also be seen.
- Ancillary: Tumours are typically positive for FOXL2, calretinin, and inhibin, and the characteristic FOXL2 point mutation can be helpful in diagnosis.
Reference Gallery:
Adult granulosa cell tumour. Microfollicular growth pattern (Call–Exner bodies) composed of monotonous tumour cells with nuclear grooves and folds and scant cytoplasm disposed around spaces filled with hyalinized material.
Adult granulosa cell tumour. Insular growth pattern.
Adult granulosa cell tumour. Macrofollicular growth pattern.
Adult granulosa cell tumour. Trabecular growth pattern.
Adult granulosa cell tumour. Fibroma-like growth.
Adult granulosa cell tumour. The tumour has a nodular appearance, with extensive areas of haemorrhage and necrosis. The nodules have a yellow and soft cut surface.
Adult granulosa cell tumour. Reticulin fibres surround groups of granulosa cells, unlike in fibroma, where reticulin fibres are present around individual cells.
Adult granulosa cell tumour. A solid and cystic, tan/cream tumour with serosanguinous fluid.

Q: A pediatric patient presenting with precocious pseudopuberty and a pelvic mass demonstrating a solid, yellow cut surface with focal cystic and hemorrhagic areas is highly characteristic of a [...].
Juvenile granulosa cell tumour. The tumour has a predominantly nodular, solid, yellow cut surface with focal cystic and haemorrhagic areas.
A: juvenile granulosa cell tumor
Back Extra: Juvenile Granulosa Cell Tumour
- Clinical: Patients with juvenile granulosa cell tumour may present with signs of a pelvic mass, estrogenic manifestations such as precocious pseudopuberty, or menstrual disturbances.
- Micro: The tumour displays a nodular or diffuse architecture with scattered follicles and abundant eosinophilic cytoplasm in the cells.
- Ancillary: Tumours typically express SF1, inhibin, calretinin, WT1, CD99, and CD56, with activating alterations in AKT1 and GNAS (gsp mutations) detected in 60% and 30% of cases, respectively.
Reference Gallery:
Juvenile granulosa cell tumour. The tumour has a predominantly nodular, solid, yellow cut surface with focal cystic and haemorrhagic areas.
Juvenile granulosa cell tumour. There is a vague nodular growth with irregular follicles showing basophilic secretion. The tumour cells have abundant eosinophilic cytoplasm. Inset: Prominent mitoses and apoptoses.

Q: Microscopically, a juvenile granulosa cell tumor typically displays a vague nodular growth pattern with irregular follicles containing basophilic secretions, and tumor cells characterized by abundant [...] cytoplasm.
Juvenile granulosa cell tumour. There is a vague nodular growth with irregular follicles showing basophilic secretion. The tumour cells have abundant eosinophilic cytoplasm. Inset: Prominent mitoses and apoptoses.
A: eosinophilic
Back Extra: Juvenile Granulosa Cell Tumour
- Clinical: Patients with juvenile granulosa cell tumour may present with signs of a pelvic mass, estrogenic manifestations such as precocious pseudopuberty, or menstrual disturbances.
- Micro: The tumour displays a nodular or diffuse architecture with scattered follicles and abundant eosinophilic cytoplasm in the cells.
- Ancillary: Tumours typically express SF1, inhibin, calretinin, WT1, CD99, and CD56, with activating alterations in AKT1 and GNAS (gsp mutations) detected in 60% and 30% of cases, respectively.
Reference Gallery:
Juvenile granulosa cell tumour. The tumour has a predominantly nodular, solid, yellow cut surface with focal cystic and haemorrhagic areas.
Juvenile granulosa cell tumour. There is a vague nodular growth with irregular follicles showing basophilic secretion. The tumour cells have abundant eosinophilic cytoplasm. Inset: Prominent mitoses and apoptoses.

Q: When a gonadal neoplasm exhibits both sex cord and stromal elements (which can be highlighted by reticulin staining) but lacks the characteristic cytological features of an adult granulosa cell tumor, lacks the tubular architecture of a Sertoli-Leydig cell tumor, and is negative for FOXL2 and DICER1 mutations, it is best classified as [...].
Sex cord–stromal tumour NOS. Both sex cord and stromal elements are present; the former can be highlighted by reticulin staining. The sex cord component lacks the cytological features of adult granulosa cell tumour and the tubular or cord-like architecture of Sertoli–Leydig cell tumour. This tumour is negative for mutations in FOXL2 and DICER1.
A: Sex Cord-Stromal Tumor NOS
Back Extra: Sex Cord-Stromal Tumour NOS
- Clinical: These tumours may be estrogenic, androgenic, or non-functioning. No data on epidemiology are available.
- Micro: Histological features are variable, but distinctive features of a specific sex cord–stromal tumour are not identifiable. Changes seen in pregnancy include prominent oedema, luteinization, and prominent Leydig cells.
- Ancillary: Immunohistochemical findings support a diagnosis of sex cord–stromal tumour, but histopathological features of a specific tumour type are not present.
Reference Gallery:
Sex cord–stromal tumour NOS. Both sex cord and stromal elements are present; the former can be highlighted by reticulin staining. The sex cord component lacks the cytological features of adult granulosa cell tumour and the tubular or cord-like architecture of Sertoli–Leydig cell tumour. This tumour is negative for mutations in FOXL2 and DICER1.

Q: An ovarian [...] typically presents with endocrine manifestations (androgenic or estrogenic) and is characterized microscopically by nests or diffuse sheets of large polygonal cells with abundant eosinophilic or vacuolated cytoplasm.
Steroid cell tumour. Low power of ovarian steroid cell tumour composed of nests of cells with abundant eosinophilic cytoplasm.
Steroid cell tumour. The tumour is composed of cells with abundant eosinophilic cytoplasm, exhibiting diffuse and follicle-like architecture.
A: Steroid Cell Tumor
Back Extra: Steroid Cell Tumour
- Clinical: Steroid cell tumours are usually unilateral, and patients often present with endocrine manifestations such as androgenic or estrogenic symptoms.
- Micro: These tumours typically consist of large polygonal cells with abundant eosinophilic or vacuolated cytoplasm and round nuclei with prominent nucleoli.
- Ancillary: Immunohistochemistry shows positivity for inhibin, calretinin, and melan-A, but negativity for FOXL2.
Reference Gallery:
Steroid cell tumour. Diffuse cytoplasmic immunoreactivity for inhibin.
Steroid cell tumour. Low power of ovarian steroid cell tumour composed of nests of cells with abundant eosinophilic cytoplasm.
Steroid cell tumour. The tumour is composed of cells with abundant eosinophilic cytoplasm, exhibiting diffuse and follicle-like architecture.

Q: Immunohistochemistry for an ovarian Steroid Cell Tumor classically shows diffuse cytoplasmic positivity for [...], as well as calretinin and melan-A, while being negative for FOXL2.
Steroid cell tumour. Diffuse cytoplasmic immunoreactivity for inhibin.
A: inhibin
Back Extra: Steroid Cell Tumour
- Clinical: Steroid cell tumours are usually unilateral, and patients often present with endocrine manifestations such as androgenic or estrogenic symptoms.
- Micro: These tumours typically consist of large polygonal cells with abundant eosinophilic or vacuolated cytoplasm and round nuclei with prominent nucleoli.
- Ancillary: Immunohistochemistry shows positivity for inhibin, calretinin, and melan-A, but negativity for FOXL2.
Reference Gallery:
Steroid cell tumour. Diffuse cytoplasmic immunoreactivity for inhibin.
Steroid cell tumour. Low power of ovarian steroid cell tumour composed of nests of cells with abundant eosinophilic cytoplasm.
Steroid cell tumour. The tumour is composed of cells with abundant eosinophilic cytoplasm, exhibiting diffuse and follicle-like architecture.

Q: Microscopically, Peritoneal Inclusion Cysts are characterized by cystic spaces lined by bland, flattened or cuboidal [...] without any invasive features.
Peritoneal inclusion cyst. Cystic spaces lined by bland mesothelial cells.
A: mesothelial cells
Back Extra: Peritoneal Inclusion Cysts
- Clinical: Peritoneal inclusion cysts are commonly incidental findings, often presenting as abdominal/pelvic masses with nonspecific symptoms.
- Micro: Peritoneal inclusion cysts are lined by bland, flattened or cuboidal mesothelial cells without invasive features.
- Ancillary: CDKN2A (p16) FISH shows no CDKN2A deletion in peritoneal inclusion cysts.
Reference Gallery:
Peritoneal inclusion cyst. Cystic spaces lined by bland mesothelial cells.
Peritoneal inclusion cyst. Gross appearance; a multiloculated cyst with thin walls and clear fluid adjacent to a piece of omental tissue.

Q: Grossly, Peritoneal Inclusion Cysts frequently present as thin-walled, clear fluid-filled [...], often found adjacent to omental or pelvic tissue.
Peritoneal inclusion cyst. Gross appearance; a multiloculated cyst with thin walls and clear fluid adjacent to a piece of omental tissue.
A: multiloculated cysts
Back Extra: Peritoneal Inclusion Cysts
- Clinical: Peritoneal inclusion cysts are commonly incidental findings, often presenting as abdominal/pelvic masses with nonspecific symptoms.
- Micro: Peritoneal inclusion cysts are lined by bland, flattened or cuboidal mesothelial cells without invasive features.
- Ancillary: CDKN2A (p16) FISH shows no CDKN2A deletion in peritoneal inclusion cysts.
Reference Gallery:
Peritoneal inclusion cyst. Cystic spaces lined by bland mesothelial cells.
Peritoneal inclusion cyst. Gross appearance; a multiloculated cyst with thin walls and clear fluid adjacent to a piece of omental tissue.

Q: Microscopically, Splenosis is characterized by a distorted architecture that mimics normal [...], often seen embedded within the fibrovascular tissue of the peritoneum.
Splenosis. Distorted splenic tissue embedded in fibrovascular tissue of peritoneum.
A: splenic tissue
Back Extra: Splenosis
- Clinical: Splenosis is usually an incidental finding, although it can cause pelvic pain, intestinal obstruction, or bleeding. It is uncommon in women and is typically seen in patients ranging in age from 29 to 60 years.
- Micro: The tissue may mimic normal spleen or show a distorted architecture. Splenosis presents as dark-red to bluish, solitary or multiple lesions ranging from a few millimetres to > 10 cm.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis and management of splenosis.
Reference Gallery:
Splenosis. Distorted splenic tissue embedded in fibrovascular tissue of peritoneum.

Q: The histologic diagnosis of Endometriosis is established by the presence of endometrial glands and stroma, frequently accompanied by evidence of old hemorrhage in the form of [...].
Nodule of endometriosis with xanthoma cells and haemosiderin. Stromal endometriosis is seen at the upper right. Endometrial glands are absent.
A: hemosiderin
Back Extra: Endometriosis
- Clinical: Patients with endometriosis commonly present with infertility, dysmenorrhoea, pelvic pain, and dyspareunia. Abdominal pain or swelling may indicate endometriosis-related tumours.
- Micro: Conventional endometriosis resembles normal endometrium, with glandular and stromal elements. The stroma can show morphological changes such as myxoid or elastotic alterations, and the epithelium can exhibit metaplastic changes.
- Ancillary: Diagnosis is confirmed by the presence of endometrial glands and stroma, often with haemorrhage or haemosiderin. Immunohistochemistry for CD10 or IFITM1 can highlight subtle lesions.
Reference Gallery:
Ovarian low-grade endometrioid carcinoma within an endometriotic cyst. The cyst lining shows transition from conventional endometriosis (right) to atypical endometriosis (left, arrow).
Atypical ovarian endometriosis. There is stratification and atypia of the epithelium transitioning to early carcinoma (right). Note the underlying endometrial-type stroma.
Endometriosis with myxoid change mimicking malignancy. Endometriosis (especially in the abdominal wall or omentum) may be associated with a prominent myxoid stromal reaction, mimicking the desmoplastic reaction associated with a malignancy.
Nodule of endometriosis with xanthoma cells and haemosiderin. Stromal endometriosis is seen at the upper right. Endometrial glands are absent.
Endometriosis of ovary. There is surrounding metaplastic/hyperplastic smooth muscle.
Endometriosis involving appendix. Endometriosis in the colonic wall has an infiltrative appearance (right).
Endometriosis involving appendix. In the appendix, endometriosis is associated with muscular hyperplasia.
Ovarian endometrioid carcinoma arising in an endometriotic cyst. There is a large solid white area representing the carcinoma juxtaposed to cysts with a smooth lining.
Ovarian endometrioid carcinoma arising in an endometriotic cyst. There is complex papillary growth within some cysts. The box outlines the area shown at high power in <<#13988>>Fig. #13988.
Endometriotic cyst. The lumen includes blood clot, imparting the gross appearance of a so-called chocolate cyst.
Endometriotic cyst. The cyst lining is mostly single-layered, with small bud-like papillae.

Q: Grossly, an ovarian cyst formed by Endometriosis is classically referred to as a [...] due to the accumulation of thick, dark, degenerated blood within the lumen.
Endometriotic cyst. The lumen includes blood clot, imparting the gross appearance of a so-called chocolate cyst.
A: "chocolate cyst"
Back Extra: Endometriosis
- Clinical: Patients with endometriosis commonly present with infertility, dysmenorrhoea, pelvic pain, and dyspareunia. Abdominal pain or swelling may indicate endometriosis-related tumours.
- Micro: Conventional endometriosis resembles normal endometrium, with glandular and stromal elements. The stroma can show morphological changes such as myxoid or elastotic alterations, and the epithelium can exhibit metaplastic changes.
- Ancillary: Diagnosis is confirmed by the presence of endometrial glands and stroma, often with haemorrhage or haemosiderin. Immunohistochemistry for CD10 or IFITM1 can highlight subtle lesions.
Reference Gallery:
Ovarian low-grade endometrioid carcinoma within an endometriotic cyst. The cyst lining shows transition from conventional endometriosis (right) to atypical endometriosis (left, arrow).
Atypical ovarian endometriosis. There is stratification and atypia of the epithelium transitioning to early carcinoma (right). Note the underlying endometrial-type stroma.
Endometriosis with myxoid change mimicking malignancy. Endometriosis (especially in the abdominal wall or omentum) may be associated with a prominent myxoid stromal reaction, mimicking the desmoplastic reaction associated with a malignancy.
Nodule of endometriosis with xanthoma cells and haemosiderin. Stromal endometriosis is seen at the upper right. Endometrial glands are absent.
Endometriosis of ovary. There is surrounding metaplastic/hyperplastic smooth muscle.
Endometriosis involving appendix. Endometriosis in the colonic wall has an infiltrative appearance (right).
Endometriosis involving appendix. In the appendix, endometriosis is associated with muscular hyperplasia.
Ovarian endometrioid carcinoma arising in an endometriotic cyst. There is a large solid white area representing the carcinoma juxtaposed to cysts with a smooth lining.
Ovarian endometrioid carcinoma arising in an endometriotic cyst. There is complex papillary growth within some cysts. The box outlines the area shown at high power in <<#13988>>Fig. #13988.
Endometriotic cyst. The lumen includes blood clot, imparting the gross appearance of a so-called chocolate cyst.
Endometriotic cyst. The cyst lining is mostly single-layered, with small bud-like papillae.

Q: Ovarian Endometriosis is a known precursor lesion that can exhibit cytologic atypia and transition directly into clear cell carcinoma or [...].
Ovarian low-grade endometrioid carcinoma within an endometriotic cyst. The cyst lining shows transition from conventional endometriosis (right) to atypical endometriosis (left, arrow).
Atypical ovarian endometriosis. There is stratification and atypia of the epithelium transitioning to early carcinoma (right). Note the underlying endometrial-type stroma.
Ovarian endometrioid carcinoma arising in an endometriotic cyst. There is a large solid white area representing the carcinoma juxtaposed to cysts with a smooth lining.
A: endometrioid carcinoma
Back Extra: Endometriosis
- Clinical: Patients with endometriosis commonly present with infertility, dysmenorrhoea, pelvic pain, and dyspareunia. Abdominal pain or swelling may indicate endometriosis-related tumours.
- Micro: Conventional endometriosis resembles normal endometrium, with glandular and stromal elements. The stroma can show morphological changes such as myxoid or elastotic alterations, and the epithelium can exhibit metaplastic changes.
- Ancillary: Diagnosis is confirmed by the presence of endometrial glands and stroma, often with haemorrhage or haemosiderin. Immunohistochemistry for CD10 or IFITM1 can highlight subtle lesions.
Reference Gallery:
Ovarian low-grade endometrioid carcinoma within an endometriotic cyst. The cyst lining shows transition from conventional endometriosis (right) to atypical endometriosis (left, arrow).
Atypical ovarian endometriosis. There is stratification and atypia of the epithelium transitioning to early carcinoma (right). Note the underlying endometrial-type stroma.
Endometriosis with myxoid change mimicking malignancy. Endometriosis (especially in the abdominal wall or omentum) may be associated with a prominent myxoid stromal reaction, mimicking the desmoplastic reaction associated with a malignancy.
Nodule of endometriosis with xanthoma cells and haemosiderin. Stromal endometriosis is seen at the upper right. Endometrial glands are absent.
Endometriosis of ovary. There is surrounding metaplastic/hyperplastic smooth muscle.
Endometriosis involving appendix. Endometriosis in the colonic wall has an infiltrative appearance (right).
Endometriosis involving appendix. In the appendix, endometriosis is associated with muscular hyperplasia.
Ovarian endometrioid carcinoma arising in an endometriotic cyst. There is a large solid white area representing the carcinoma juxtaposed to cysts with a smooth lining.
Ovarian endometrioid carcinoma arising in an endometriotic cyst. There is complex papillary growth within some cysts. The box outlines the area shown at high power in <<#13988>>Fig. #13988.
Endometriotic cyst. The lumen includes blood clot, imparting the gross appearance of a so-called chocolate cyst.
Endometriotic cyst. The cyst lining is mostly single-layered, with small bud-like papillae.

Q: In Endosalpingiosis, the classic microscopic finding is the presence of cystic or glandular structures lined by a single layer of bland [...] epithelium.
Endosalpingiosis. Cystic structure lined by bland tubal-type epithelium in omentum.
Endosalpingiosis. Glandular structure lined by bland tubal-type epithelium in lymph node capsule.
A: tubal-type
Back Extra: Endosalpingiosis
- Clinical: Endosalpingiosis is usually an incidental finding and occurs in as many as 12.5% of women, with a wide age range.
- Micro: Endosalpingiosis is lined by a single layer of tubal-like epithelium, sometimes associated with psammoma bodies. Small papillae or epithelial proliferation without cell detachment can be seen.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of endosalpingiosis.
Reference Gallery:
Endosalpingiosis. Cystic structure lined by bland tubal-type epithelium in omentum.
Endosalpingiosis. Glandular structure lined by bland tubal-type epithelium in lymph node capsule.

Q: [...] is a typically incidental finding characterized microscopically by cystic or glandular structures lined by a single layer of bland tubal-type epithelium.
Endosalpingiosis. Cystic structure lined by bland tubal-type epithelium in omentum.
Endosalpingiosis. Glandular structure lined by bland tubal-type epithelium in lymph node capsule.
A: Endosalpingiosis
Back Extra: Endosalpingiosis
- Clinical: Endosalpingiosis is usually an incidental finding and occurs in as many as 12.5% of women, with a wide age range.
- Micro: Endosalpingiosis is lined by a single layer of tubal-like epithelium, sometimes associated with psammoma bodies. Small papillae or epithelial proliferation without cell detachment can be seen.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of endosalpingiosis.
Reference Gallery:
Endosalpingiosis. Cystic structure lined by bland tubal-type epithelium in omentum.
Endosalpingiosis. Glandular structure lined by bland tubal-type epithelium in lymph node capsule.

Q: In Other Tumour-like Lesions of the Peritoneum, microscopic examination may incidentally reveal [...], which are characterized by laminated keratinous debris or ghost squamous cells surrounded by foreign body–type giant cells.
Keratin granuloma. Keratinous debris surrounded by foreign body–type giant cells.
A: keratin granulomas
Back Extra: Other Tumour-like Lesions of the Peritoneum
- Clinical: These lesions are usually incidental findings and are benign.
- Micro: Keratin granulomas show laminated keratin or ghost squamous cells surrounded by foreign body–type giant cells, histiocytes, and inflammatory cells.
- Ancillary: Ancillary studies are not clinically relevant for these lesions.
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Keratin granuloma. Keratinous debris surrounded by foreign body–type giant cells.

Q: Microscopically, [...] is characterized by cystic lesions with a fibrous wall containing papillae and abundant concentric calcifications known as psammoma bodies.
Serous borderline tumour of the peritoneum. Cystic lesion of the peritoneum with a fibrous wall showing papillae and psammoma bodies. Focally, the fibrous tissue is densely infiltrated by inflammatory cells.
Serous borderline tumour of the peritoneum. The lesion consists of multiple papillae and large psammomatous calcifications, partially in the stroma of the papillae.
A: serous borderline tumor of the peritoneum
Back Extra: Serous Borderline Tumour of the Peritoneum
- Clinical: Patients with Serous Borderline Tumour of the Peritoneum typically present with symptoms of an abdominal/pelvic mass, ascites, and adhesions. The mean age at diagnosis is 31-33 years.
- Micro: Microscopically, the tumours show cystic lesions with a fibrous wall containing papillae and psammoma bodies. The papillae are covered by proliferative serous epithelium with mild atypia and tufting.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of Serous Borderline Tumour of the Peritoneum.
Reference Gallery:
Serous borderline tumour of the peritoneum. Cystic lesion of the peritoneum with a fibrous wall showing papillae and psammoma bodies. Focally, the fibrous tissue is densely infiltrated by inflammatory cells.
Serous borderline tumour of the peritoneum. The lesion consists of multiple papillae and large psammomatous calcifications, partially in the stroma of the papillae.
Serous borderline tumour of the peritoneum. The papillae are covered by proliferative serous epithelium, which shows mild atypia, tufting, and detachment from the surface.
Serous borderline tumour of the peritoneum. The dense fibrous tissue contains small psammoma bodies and glandular structures.

Q: The papillae in a serous borderline tumor of the peritoneum are lined by proliferative serous epithelium that typically demonstrates mild atypia, detachment, and epithelial [...].
Serous borderline tumour of the peritoneum. The papillae are covered by proliferative serous epithelium, which shows mild atypia, tufting, and detachment from the surface.
A: tufting
Back Extra: Serous Borderline Tumour of the Peritoneum
- Clinical: Patients with Serous Borderline Tumour of the Peritoneum typically present with symptoms of an abdominal/pelvic mass, ascites, and adhesions. The mean age at diagnosis is 31-33 years.
- Micro: Microscopically, the tumours show cystic lesions with a fibrous wall containing papillae and psammoma bodies. The papillae are covered by proliferative serous epithelium with mild atypia and tufting.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of Serous Borderline Tumour of the Peritoneum.
Reference Gallery:
Serous borderline tumour of the peritoneum. Cystic lesion of the peritoneum with a fibrous wall showing papillae and psammoma bodies. Focally, the fibrous tissue is densely infiltrated by inflammatory cells.
Serous borderline tumour of the peritoneum. The lesion consists of multiple papillae and large psammomatous calcifications, partially in the stroma of the papillae.
Serous borderline tumour of the peritoneum. The papillae are covered by proliferative serous epithelium, which shows mild atypia, tufting, and detachment from the surface.
Serous borderline tumour of the peritoneum. The dense fibrous tissue contains small psammoma bodies and glandular structures.

Q: Microscopically, Pseudomyxoma peritonei is characterized by the massive intraperitoneal accumulation of abundant [...] pools containing varying degrees of neoplastic epithelial cellularity.
Pseudomyxoma peritonei, grade 1. Low-power view shows abundant mucin with scant cohesive strips of low-grade mucinous epithelium.
Pseudomyxoma peritonei, grade 2. Low-power view shows numerous small mucin pools with many small glandular epithelial cell groups and clusters.
A: mucin
Back Extra: Pseudomyxoma peritonei
- Clinical: Pseudomyxoma peritonei often presents with symptoms of appendicitis, increasing abdominal girth, abdominal pain, or mucin within a hernia sac.
- Micro: Abundant mucin with varying degrees of tumour cellularity is characteristic; histological grading is based on tumour cellularity, cytological and architectural atypia, and the presence of signet-ring cells.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of pseudomyxoma peritonei.
Reference Gallery:
Pseudomyxoma peritonei, grade 1. Low-power view shows abundant mucin with scant cohesive strips of low-grade mucinous epithelium.
Pseudomyxoma peritonei, grade 1. High-power view of peritoneal mucinous tumour deposit shows a strip of mucinous epithelium with low-grade cytological atypia.
Pseudomyxoma peritonei, grade 2. Low-power view shows numerous small mucin pools with many small glandular epithelial cell groups and clusters.
Pseudomyxoma peritonei, grade 2. High-power view of this mucinous tumour deposit shows a complex epithelial group with high-grade cytological features, including enlarged vesicular nuclei and nucleoli.
Pseudomyxoma peritonei, grade 3. A mucinous tumour deposit within the peritoneum composed of small glandular clusters, including many with a signet-ring morphology. The stroma shows a desmoplastic response.

Q: When grading Pseudomyxoma peritonei, grade 3 tumor deposits are distinguished by small glandular clusters featuring [...] cells and a desmoplastic stromal response.
Pseudomyxoma peritonei, grade 3. A mucinous tumour deposit within the peritoneum composed of small glandular clusters, including many with a signet-ring morphology. The stroma shows a desmoplastic response.
A: signet-ring
Back Extra: Pseudomyxoma peritonei
- Clinical: Pseudomyxoma peritonei often presents with symptoms of appendicitis, increasing abdominal girth, abdominal pain, or mucin within a hernia sac.
- Micro: Abundant mucin with varying degrees of tumour cellularity is characteristic; histological grading is based on tumour cellularity, cytological and architectural atypia, and the presence of signet-ring cells.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of pseudomyxoma peritonei.
Reference Gallery:
Pseudomyxoma peritonei, grade 1. Low-power view shows abundant mucin with scant cohesive strips of low-grade mucinous epithelium.
Pseudomyxoma peritonei, grade 1. High-power view of peritoneal mucinous tumour deposit shows a strip of mucinous epithelium with low-grade cytological atypia.
Pseudomyxoma peritonei, grade 2. Low-power view shows numerous small mucin pools with many small glandular epithelial cell groups and clusters.
Pseudomyxoma peritonei, grade 2. High-power view of this mucinous tumour deposit shows a complex epithelial group with high-grade cytological features, including enlarged vesicular nuclei and nucleoli.
Pseudomyxoma peritonei, grade 3. A mucinous tumour deposit within the peritoneum composed of small glandular clusters, including many with a signet-ring morphology. The stroma shows a desmoplastic response.

Q: The diagnosis of Low-grade serous carcinoma of the peritoneum requires the presence of infiltrating papillary or micropapillary structures exhibiting a low mitotic count and [...] cytological atypia.
Low-grade serous carcinoma of the peritoneum. Papillary structures and single cells, showing mild to moderate cytological atypia and rare mitoses, infiltrate fibroconnective tissue.
A: mild to moderate
Back Extra: Low-grade serous carcinoma of the peritoneum
- Clinical: Most patients present with abdominal pain or distension. Patient age ranges from 27 to 82 years (median: 52 years).
- Micro: Neoplastic cells show mild to moderate cytological atypia and a low mitotic count. Architectural patterns include papillary, micropapillary, cribriform, and solid patterns.
- Ancillary: No clinically relevant ancillary studies are typically performed.
Reference Gallery:
Low-grade serous carcinoma of the peritoneum. Papillary structures and single cells, showing mild to moderate cytological atypia and rare mitoses, infiltrate fibroconnective tissue.

Q: Microscopically, Low-grade serous carcinoma of the peritoneum typically demonstrates a low mitotic count and forms complex architectures, most classically [...] or micropapillary structures infiltrating fibroconnective tissue.
Low-grade serous carcinoma of the peritoneum. Papillary structures and single cells, showing mild to moderate cytological atypia and rare mitoses, infiltrate fibroconnective tissue.
A: papillary
Back Extra: Low-grade serous carcinoma of the peritoneum
- Clinical: Most patients present with abdominal pain or distension. Patient age ranges from 27 to 82 years (median: 52 years).
- Micro: Neoplastic cells show mild to moderate cytological atypia and a low mitotic count. Architectural patterns include papillary, micropapillary, cribriform, and solid patterns.
- Ancillary: No clinically relevant ancillary studies are typically performed.
Reference Gallery:
Low-grade serous carcinoma of the peritoneum. Papillary structures and single cells, showing mild to moderate cytological atypia and rare mitoses, infiltrate fibroconnective tissue.

Q: Microscopically, Calcifying Fibrous Tumor is characterized by abundant hypocellular hyalinized collagen, a chronic lymphoplasmacytic infiltrate, and scattered [...].
Calcifying fibrous tumour. The tumour is hypocellular and associated with hyalinized collagen and calcification.
Calcifying fibrous tumour. The tumour shows scattered psammomatous calcifications within dense collagenous stroma.
A: psammomatous calcifications
Back Extra: Calcifying Fibrous Tumour
- Clinical: Calcifying fibrous tumours are typically identified incidentally and may cause symptoms related to an abdominal mass. They have a female predilection and are most common in infants, young children, and young adults.
- Micro: The tumour is characterized by abundant hypocellular hyalinized collagen, scattered psammomatous calcifications, and a chronic lymphoplasmacytic infiltrate.
- Ancillary: Tumours are usually diffusely positive for factor XIIIa and CD34, but molecular and genetic studies are not clinically relevant.
Reference Gallery:
Calcifying fibrous tumour. The tumour is hypocellular and associated with hyalinized collagen and calcification.
Calcifying fibrous tumour. The tumour shows scattered psammomatous calcifications within dense collagenous stroma.
Calcifying fibrous tumour. There is often chronic lymphoplasmacytic infiltration with lymphoid follicle formation.

Q: Alongside dense collagen and calcifications, a classic histologic feature of Calcifying Fibrous Tumor is a chronic [...] infiltrate, which often forms lymphoid follicles.
Calcifying fibrous tumour. There is often chronic lymphoplasmacytic infiltration with lymphoid follicle formation.
A: lymphoplasmacytic
Back Extra: Calcifying Fibrous Tumour
- Clinical: Calcifying fibrous tumours are typically identified incidentally and may cause symptoms related to an abdominal mass. They have a female predilection and are most common in infants, young children, and young adults.
- Micro: The tumour is characterized by abundant hypocellular hyalinized collagen, scattered psammomatous calcifications, and a chronic lymphoplasmacytic infiltrate.
- Ancillary: Tumours are usually diffusely positive for factor XIIIa and CD34, but molecular and genetic studies are not clinically relevant.
Reference Gallery:
Calcifying fibrous tumour. The tumour is hypocellular and associated with hyalinized collagen and calcification.
Calcifying fibrous tumour. The tumour shows scattered psammomatous calcifications within dense collagenous stroma.
Calcifying fibrous tumour. There is often chronic lymphoplasmacytic infiltration with lymphoid follicle formation.

Q: Microscopically, Desmoid Fibromatosis features an infiltrative proliferation of bland fibroblasts and myofibroblasts arranged in characteristic [...].
Desmoid fibromatosis. Long sweeping fascicles of bland fibroblasts and myofibroblasts.
Desmoid fibromatosis. High-power examination reveals the lack of nuclear atypia.
A: long sweeping fascicles
Back Extra: Desmoid Fibromatosis
- Clinical: As many as 50% of patients with Desmoid Fibromatosis present with pain, while urinary symptoms and obstructed labour may occur in pregnant patients.
- Micro: Desmoid Fibromatosis shows an infiltrative proliferation of bland fibroblasts/myofibroblasts arranged in long sweeping fascicles.
- Ancillary: Most sporadic cases of Desmoid Fibromatosis harbour point mutations in CTNNB1, and tumour cells show nuclear expression of β-catenin by immunohistochemistry.
Reference Gallery:
Desmoid fibromatosis. The tumour cells show nuclear expression of β-catenin by immunohistochemistry.
Desmoid fibromatosis. Long sweeping fascicles of bland fibroblasts and myofibroblasts.
Desmoid fibromatosis. High-power examination reveals the lack of nuclear atypia.

Q: In Desmoid Fibromatosis, most sporadic cases harbor CTNNB1 point mutations, leading to diagnostic nuclear expression of [...] on immunohistochemistry.
Desmoid fibromatosis. The tumour cells show nuclear expression of β-catenin by immunohistochemistry.
A: β-catenin
Back Extra: Desmoid Fibromatosis
- Clinical: As many as 50% of patients with Desmoid Fibromatosis present with pain, while urinary symptoms and obstructed labour may occur in pregnant patients.
- Micro: Desmoid Fibromatosis shows an infiltrative proliferation of bland fibroblasts/myofibroblasts arranged in long sweeping fascicles.
- Ancillary: Most sporadic cases of Desmoid Fibromatosis harbour point mutations in CTNNB1, and tumour cells show nuclear expression of β-catenin by immunohistochemistry.
Reference Gallery:
Desmoid fibromatosis. The tumour cells show nuclear expression of β-catenin by immunohistochemistry.
Desmoid fibromatosis. Long sweeping fascicles of bland fibroblasts and myofibroblasts.
Desmoid fibromatosis. High-power examination reveals the lack of nuclear atypia.

Q: Microscopically, Gliomatosis is characterized by discrete nodules of mature [...] embedded in a peritoneal fibrous stroma, occasionally associated with inflammation, hemorrhage, and fibrosis.
Gliomatosis. Nodules of mature glial tissue embedded in peritoneal fibrous stroma.
A: glial tissue
Q: Gliomatosis
- Clinical: Patients with [...] often present with symptoms related to an ovarian teratoma, but can also have abdominal/pelvic pain due to the formation of glial masses.
- Micro: Microscopically, [...] shows discrete nodules of mature glial tissue, occasionally associated with inflammation, haemorrhage, and fibrosis.
- Ancillary: Immunohistochemistry for [...] shows the nodules to be positive for GFAP and SOX2, and variably positive for S100.
Reference Gallery:
Gliomatosis. Nodules of mature glial tissue embedded in peritoneal fibrous stroma.
A: gliomatosis; gliomatosis; gliomatosis

Q: Patients with Gliomatosis typically develop peritoneal implants of mature glial masses in association with an [...].
Gliomatosis. Nodules of mature glial tissue embedded in peritoneal fibrous stroma.
A: ovarian teratoma
Q: Gliomatosis
- Clinical: Patients with [...] often present with symptoms related to an ovarian teratoma, but can also have abdominal/pelvic pain due to the formation of glial masses.
- Micro: Microscopically, [...] shows discrete nodules of mature glial tissue, occasionally associated with inflammation, haemorrhage, and fibrosis.
- Ancillary: Immunohistochemistry for [...] shows the nodules to be positive for GFAP and SOX2, and variably positive for S100.
Reference Gallery:
Gliomatosis. Nodules of mature glial tissue embedded in peritoneal fibrous stroma.
A: gliomatosis; gliomatosis; gliomatosis

Q: Microscopically, Leiomyomatosis peritonealis disseminata features fascicles of cytologically [...] cells that lack mitotic figures and can often infiltrate surrounding fat.
Leiomyomatosis peritonealis disseminata. Benign smooth muscle cells infiltrate the fat.
Leiomyomatosis peritonealis disseminata. Spindle cells are cytologically benign and lack mitotic figures.
A: benign smooth muscle
Back Extra: Leiomyomatosis peritonealis disseminata
- Clinical: Leiomyomatosis peritonealis disseminata is often an incidental finding at the time of caesarean section or postpartum tubal ligation.
- Micro: The nodules resemble typical or cellular leiomyomas with spindle cells arranged in fascicles and mild nuclear atypia.
- Ancillary: MED12 mutations have been demonstrated, but the mutation status in individual peritoneal nodules and concurrent uterine leiomyomas may differ.
Reference Gallery:
Leiomyomatosis peritonealis disseminata. Benign smooth muscle cells infiltrate the fat.
Leiomyomatosis peritonealis disseminata. Multiple smooth muscle tumour nodules are present in the omentum.
Leiomyomatosis peritonealis disseminata. Spindle cells are cytologically benign and lack mitotic figures.
Leiomyomatosis peritonealis disseminata. Multiple confluent small nodules are seen. They show a uniform white cut surface.

Q: Grossly, Leiomyomatosis peritonealis disseminata consists of multiple, confluent small nodules with a uniform white cut surface, which are classically discovered as an incidental finding during a [...] or postpartum tubal ligation.
Leiomyomatosis peritonealis disseminata. Multiple smooth muscle tumour nodules are present in the omentum.
Leiomyomatosis peritonealis disseminata. Multiple confluent small nodules are seen. They show a uniform white cut surface.
A: cesarean section
Back Extra: Leiomyomatosis peritonealis disseminata
- Clinical: Leiomyomatosis peritonealis disseminata is often an incidental finding at the time of caesarean section or postpartum tubal ligation.
- Micro: The nodules resemble typical or cellular leiomyomas with spindle cells arranged in fascicles and mild nuclear atypia.
- Ancillary: MED12 mutations have been demonstrated, but the mutation status in individual peritoneal nodules and concurrent uterine leiomyomas may differ.
Reference Gallery:
Leiomyomatosis peritonealis disseminata. Benign smooth muscle cells infiltrate the fat.
Leiomyomatosis peritonealis disseminata. Multiple smooth muscle tumour nodules are present in the omentum.
Leiomyomatosis peritonealis disseminata. Spindle cells are cytologically benign and lack mitotic figures.
Leiomyomatosis peritonealis disseminata. Multiple confluent small nodules are seen. They show a uniform white cut surface.

Q: Histologically, Solitary Fibrous Tumor of the Peritoneum features spindled to ovoid cells growing in a "patternless" architecture, typically containing prominent branching, thin-walled [...] blood vessels.
Solitary fibrous tumour. A proliferation of spindled and ovoid cells growing in a patternless fashion, with branching, thin-walled staghorn blood vessels within a collagenous stroma.
A: staghorn
Back Extra: Solitary Fibrous Tumour of the Peritoneum
- Clinical: Solitary Fibrous Tumour of the Peritoneum usually presents with an abdominal mass, often associated with pain and occasionally hypoglycaemia.
- Micro: The tumour is characterized by spindled to ovoid cells with indistinct, eosinophilic cytoplasm growing in a patternless fashion within a collagenous stroma, with branching, thin-walled staghorn blood vessels.
- Ancillary: NAB2-STAT6 gene fusions are pathognomonic for Solitary Fibrous Tumour of the Peritoneum and can be detected using STAT6 immunohistochemistry.
Reference Gallery:
Solitary fibrous tumour. A proliferation of spindled and ovoid cells growing in a patternless fashion, with branching, thin-walled staghorn blood vessels within a collagenous stroma.

Q: A mesenchymal neoplasm presenting in the abdominal cavity that shows a "patternless" proliferation of spindled cells, a collagenous stroma, and branching, thin-walled "staghorn" blood vessels is highly characteristic of [...].
Solitary fibrous tumour. A proliferation of spindled and ovoid cells growing in a patternless fashion, with branching, thin-walled staghorn blood vessels within a collagenous stroma.
A: Solitary Fibrous Tumor of the Peritoneum
Back Extra: Solitary Fibrous Tumour of the Peritoneum
- Clinical: Solitary Fibrous Tumour of the Peritoneum usually presents with an abdominal mass, often associated with pain and occasionally hypoglycaemia.
- Micro: The tumour is characterized by spindled to ovoid cells with indistinct, eosinophilic cytoplasm growing in a patternless fashion within a collagenous stroma, with branching, thin-walled staghorn blood vessels.
- Ancillary: NAB2-STAT6 gene fusions are pathognomonic for Solitary Fibrous Tumour of the Peritoneum and can be detected using STAT6 immunohistochemistry.
Reference Gallery:
Solitary fibrous tumour. A proliferation of spindled and ovoid cells growing in a patternless fashion, with branching, thin-walled staghorn blood vessels within a collagenous stroma.

Q: Histologically, Desmoplastic Small Round Cell Tumor features nests of small round cells embedded in a prominent [...].
Desmoplastic small round cell tumour. The tumour is composed of sheets of cells with scant cytoplasm embedded in a fibrous stroma.
A: desmoplastic stroma
Back Extra: Desmoplastic Small Round Cell Tumour
- Clinical: Patients with Desmoplastic Small Round Cell Tumour (DSRCT) typically present with abdominal pain, distension, a palpable mass, ascites, or symptoms of bowel obstruction.
- Micro: DSRCT is characterized by nests of small round cells surrounded by a prominent desmoplastic stroma, with frequent central necrosis and cystic degeneration.
- Ancillary: The presence of EWSR1-WT1 gene fusion and immunoreactivity for cytokeratins, EMA, and desmin are key diagnostic features of DSRCT.
Reference Gallery:
Desmoplastic small round cell tumour. Punctate cytoplasmic staining with desmin.
Desmoplastic small round cell tumour. The tumour is composed of sheets of cells with scant cytoplasm embedded in a fibrous stroma.

Q: In Desmoplastic Small Round Cell Tumor, the characteristic immunohistochemical staining pattern for desmin is typically [...].
Desmoplastic small round cell tumour. Punctate cytoplasmic staining with desmin.
A: punctate cytoplasmic
Back Extra: Desmoplastic Small Round Cell Tumour
- Clinical: Patients with Desmoplastic Small Round Cell Tumour (DSRCT) typically present with abdominal pain, distension, a palpable mass, ascites, or symptoms of bowel obstruction.
- Micro: DSRCT is characterized by nests of small round cells surrounded by a prominent desmoplastic stroma, with frequent central necrosis and cystic degeneration.
- Ancillary: The presence of EWSR1-WT1 gene fusion and immunoreactivity for cytokeratins, EMA, and desmin are key diagnostic features of DSRCT.
Reference Gallery:
Desmoplastic small round cell tumour. Punctate cytoplasmic staining with desmin.
Desmoplastic small round cell tumour. The tumour is composed of sheets of cells with scant cytoplasm embedded in a fibrous stroma.

Q: An aggressive intra-abdominal malignancy featuring nests of cells in a fibrous background, punctate desmin staining, and an EWSR1-WT1 gene fusion is diagnostic of [...].
Desmoplastic small round cell tumour. Punctate cytoplasmic staining with desmin.
Desmoplastic small round cell tumour. The tumour is composed of sheets of cells with scant cytoplasm embedded in a fibrous stroma.
A: Desmoplastic Small Round Cell Tumor
Back Extra: Desmoplastic Small Round Cell Tumour
- Clinical: Patients with Desmoplastic Small Round Cell Tumour (DSRCT) typically present with abdominal pain, distension, a palpable mass, ascites, or symptoms of bowel obstruction.
- Micro: DSRCT is characterized by nests of small round cells surrounded by a prominent desmoplastic stroma, with frequent central necrosis and cystic degeneration.
- Ancillary: The presence of EWSR1-WT1 gene fusion and immunoreactivity for cytokeratins, EMA, and desmin are key diagnostic features of DSRCT.
Reference Gallery:
Desmoplastic small round cell tumour. Punctate cytoplasmic staining with desmin.
Desmoplastic small round cell tumour. The tumour is composed of sheets of cells with scant cytoplasm embedded in a fibrous stroma.

Q: In diagnostic workup, Extragastrointestinal Stromal Tumor is characteristically positive for KIT (CD117) and [...] (ANO1) by immunohistochemistry.
Extragastrointestinal stromal tumour. A primary omental gastrointestinal stromal tumour with mixed spindle cell and epithelioid morphology (shown here). Immunohistochemistry for KIT is negative (shown in Fig. #13470), whereas DOG1 (ANO1) is diffusely positive (shown in Fig. #13471). KIT-negative gastrointestinal stromal tumours often harbour PDGFRA mutations.
Extragastrointestinal stromal tumour. A primary omental gastrointestinal stromal tumour with mixed spindle cell and epithelioid morphology (shown in Fig. #13469). Immunohistochemistry for KIT is negative (shown in Fig. #13470), whereas DOG1 (ANO1) is diffusely positive (shown here). KIT-negative gastrointestinal stromal tumours often harbour PDGFRA mutations.
A: DOG1
Back Extra: Extragastrointestinal Stromal Tumour
- Clinical: Extragastrointestinal stromal tumours (EGISTs) commonly present as an abdominopelvic mass, often with abdominal discomfort or pain, and can be asymptomatic and detected incidentally.
- Micro: Histologically, EGISTs can show spindled, epithelioid, vacuolated, nested, or myxoid patterns, similar to GISTs in the gastrointestinal tract.
- Ancillary: Immunohistochemically, EGISTs are often positive for KIT (CD117) and DOG1 (ANO1), with CD34 more commonly positive in spindle cell variants. PDGFRA mutations are frequent in KIT-negative cases.
Reference Gallery:
Extragastrointestinal stromal tumour. A primary omental gastrointestinal stromal tumour with mixed spindle cell and epithelioid morphology (shown here). Immunohistochemistry for KIT is negative (shown in Fig. #13470), whereas DOG1 (ANO1) is diffusely positive (shown in Fig. #13471). KIT-negative gastrointestinal stromal tumours often harbour PDGFRA mutations.
Extragastrointestinal stromal tumour. A primary omental gastrointestinal stromal tumour with mixed spindle cell and epithelioid morphology (shown in Fig. #13469). Immunohistochemistry for KIT is negative (shown here), whereas DOG1 (ANO1) is diffusely positive (shown in Fig. #13471). KIT-negative gastrointestinal stromal tumours often harbour PDGFRA mutations.
Extragastrointestinal stromal tumour. A primary omental gastrointestinal stromal tumour with mixed spindle cell and epithelioid morphology (shown in Fig. #13469). Immunohistochemistry for KIT is negative (shown in Fig. #13470), whereas DOG1 (ANO1) is diffusely positive (shown here). KIT-negative gastrointestinal stromal tumours often harbour PDGFRA mutations.
Extragastrointestinal stromal tumour. A primary omental gastrointestinal stromal tumour of epithelioid type with myxoid stroma. This tumour harboured a PDGFRA p.Asp842Val mutation.

Q: When an Extragastrointestinal Stromal Tumor is immunohistochemically negative for KIT, it frequently harbors a mutation in the [...] gene.
Extragastrointestinal stromal tumour. A primary omental gastrointestinal stromal tumour with mixed spindle cell and epithelioid morphology (shown in Fig. #13469). Immunohistochemistry for KIT is negative (shown here), whereas DOG1 (ANO1) is diffusely positive (shown in Fig. #13471). KIT-negative gastrointestinal stromal tumours often harbour PDGFRA mutations.
Extragastrointestinal stromal tumour. A primary omental gastrointestinal stromal tumour of epithelioid type with myxoid stroma. This tumour harboured a PDGFRA p.Asp842Val mutation.
A: PDGFRA
Back Extra: Extragastrointestinal Stromal Tumour
- Clinical: Extragastrointestinal stromal tumours (EGISTs) commonly present as an abdominopelvic mass, often with abdominal discomfort or pain, and can be asymptomatic and detected incidentally.
- Micro: Histologically, EGISTs can show spindled, epithelioid, vacuolated, nested, or myxoid patterns, similar to GISTs in the gastrointestinal tract.
- Ancillary: Immunohistochemically, EGISTs are often positive for KIT (CD117) and DOG1 (ANO1), with CD34 more commonly positive in spindle cell variants. PDGFRA mutations are frequent in KIT-negative cases.
Reference Gallery:
Extragastrointestinal stromal tumour. A primary omental gastrointestinal stromal tumour with mixed spindle cell and epithelioid morphology (shown here). Immunohistochemistry for KIT is negative (shown in Fig. #13470), whereas DOG1 (ANO1) is diffusely positive (shown in Fig. #13471). KIT-negative gastrointestinal stromal tumours often harbour PDGFRA mutations.
Extragastrointestinal stromal tumour. A primary omental gastrointestinal stromal tumour with mixed spindle cell and epithelioid morphology (shown in Fig. #13469). Immunohistochemistry for KIT is negative (shown here), whereas DOG1 (ANO1) is diffusely positive (shown in Fig. #13471). KIT-negative gastrointestinal stromal tumours often harbour PDGFRA mutations.
Extragastrointestinal stromal tumour. A primary omental gastrointestinal stromal tumour with mixed spindle cell and epithelioid morphology (shown in Fig. #13469). Immunohistochemistry for KIT is negative (shown in Fig. #13470), whereas DOG1 (ANO1) is diffusely positive (shown here). KIT-negative gastrointestinal stromal tumours often harbour PDGFRA mutations.
Extragastrointestinal stromal tumour. A primary omental gastrointestinal stromal tumour of epithelioid type with myxoid stroma. This tumour harboured a PDGFRA p.Asp842Val mutation.

Q: An incidental, reactive lesion characterized by compact, nodular aggregates of histiocytes with oval or kidney-shaped nuclei that are negative for calretinin and CK5/6 is diagnosed as a [...].
Histiocytic nodule. Compact proliferation of histiocytes with oval or kidney-shaped nuclei.
A: Histiocytic Nodule
Back Extra: Histiocytic Nodule
- Clinical: Histiocytic nodules are usually incidental findings, seen in patients ranging from 6 to 70 years of age and resulting from nonspecific reactions to injury, inflammation, or the presence of a tumor.
- Micro: Characterized by a compact and nodular aggregate of histiocytes with oval or kidney-shaped nuclei, often mixed with mesothelial cells and fibrinous material.
- Ancillary: Immunohistochemistry shows histiocytes positive for CD68, CD16, CD163, lysozyme, CD4, and CD64, but negative for calretinin and CK5/6.
Reference Gallery:
Histiocytic nodule. Compact proliferation of histiocytes with oval or kidney-shaped nuclei.
Histiocytic nodule. CD68 immunoreactivity in histiocytes.
Nodular histiocytic hyperplasia. Nodular aggregates of polygonal to ovoid histiocytes enmeshed in a fibrin deposit, which is often resembling an epithelial neoplasm.
Histiocytic nodule. Nodular aggregates of polygonal to ovoid histiocytes enmeshed in a fibrin deposit, which is often resembling an epithelial neoplasm.
Histiocytic nodule. Nodular and compact aggregates of histiocytes enmeshed in fibrin, frequently resembling an epithelial neoplasm.

Q: Microscopically, a Histiocytic Nodule features compact aggregates of polygonal to ovoid histiocytes that are often enmeshed in a deposit of [...], which can make the lesion resemble an epithelial neoplasm.
Histiocytic nodule. Nodular aggregates of polygonal to ovoid histiocytes enmeshed in a fibrin deposit, which is often resembling an epithelial neoplasm.
Histiocytic nodule. Nodular and compact aggregates of histiocytes enmeshed in fibrin, frequently resembling an epithelial neoplasm.
A: fibrin
Back Extra: Histiocytic Nodule
- Clinical: Histiocytic nodules are usually incidental findings, seen in patients ranging from 6 to 70 years of age and resulting from nonspecific reactions to injury, inflammation, or the presence of a tumor.
- Micro: Characterized by a compact and nodular aggregate of histiocytes with oval or kidney-shaped nuclei, often mixed with mesothelial cells and fibrinous material.
- Ancillary: Immunohistochemistry shows histiocytes positive for CD68, CD16, CD163, lysozyme, CD4, and CD64, but negative for calretinin and CK5/6.
Reference Gallery:
Histiocytic nodule. Compact proliferation of histiocytes with oval or kidney-shaped nuclei.
Histiocytic nodule. CD68 immunoreactivity in histiocytes.
Nodular histiocytic hyperplasia. Nodular aggregates of polygonal to ovoid histiocytes enmeshed in a fibrin deposit, which is often resembling an epithelial neoplasm.
Histiocytic nodule. Nodular aggregates of polygonal to ovoid histiocytes enmeshed in a fibrin deposit, which is often resembling an epithelial neoplasm.
Histiocytic nodule. Nodular and compact aggregates of histiocytes enmeshed in fibrin, frequently resembling an epithelial neoplasm.

Q: To confirm the diagnosis of a Histiocytic Nodule and differentiate it from mesothelial or epithelial proliferations, immunohistochemistry typically demonstrates strong positivity for macrophage markers such as [...].
Histiocytic nodule. CD68 immunoreactivity in histiocytes.
A: CD68
Back Extra: Histiocytic Nodule
- Clinical: Histiocytic nodules are usually incidental findings, seen in patients ranging from 6 to 70 years of age and resulting from nonspecific reactions to injury, inflammation, or the presence of a tumor.
- Micro: Characterized by a compact and nodular aggregate of histiocytes with oval or kidney-shaped nuclei, often mixed with mesothelial cells and fibrinous material.
- Ancillary: Immunohistochemistry shows histiocytes positive for CD68, CD16, CD163, lysozyme, CD4, and CD64, but negative for calretinin and CK5/6.
Reference Gallery:
Histiocytic nodule. Compact proliferation of histiocytes with oval or kidney-shaped nuclei.
Histiocytic nodule. CD68 immunoreactivity in histiocytes.
Nodular histiocytic hyperplasia. Nodular aggregates of polygonal to ovoid histiocytes enmeshed in a fibrin deposit, which is often resembling an epithelial neoplasm.
Histiocytic nodule. Nodular aggregates of polygonal to ovoid histiocytes enmeshed in a fibrin deposit, which is often resembling an epithelial neoplasm.
Histiocytic nodule. Nodular and compact aggregates of histiocytes enmeshed in fibrin, frequently resembling an epithelial neoplasm.

Q: In Mesothelial Hyperplasia, histology often reveals hyperplastic cells proliferating on tissue surfaces (e.g., adipose tissue, as seen here) forming small aggregates, sheets, cords, and [...] structures, frequently admixed with inflammation.
Mesothelial hyperplasia. Proliferation of mesothelial cells on the surface of adipose tissue.
A: tubulopapillary
Back Extra: Mesothelial Hyperplasia
- Clinical: Mesothelial hyperplasia is usually asymptomatic and is often an incidental finding during surgery or biopsy for other conditions.
- Micro: The hyperplastic mesothelial cells grow in small aggregates, sheets, cords, and tubulopapillary structures, often admixed with inflammation.
- Ancillary: Mesothelial hyperplasia lacks BAP1 mutations and homozygous deletion of CDKN2A (p16) by FISH.
Reference Gallery:
Mesothelial hyperplasia. Proliferation of mesothelial cells on the surface of adipose tissue.

Q: An incidentally found mesothelial lesion characterized by fibrovascular cores with minimal branching, lined by a single layer of bland cuboidal cells, is diagnostic of [...].
Well-differentiated papillary mesothelial tumour. The tumour is composed of fibrovascular cores with minimal branching, lined by bland cuboidal cells.
Well-differentiated papillary mesothelial tumour. Diffuse calretinin positivity.
A: well-differentiated papillary mesothelial tumor
Back Extra: Well-differentiated Papillary Mesothelial Tumour
- Clinical: Well-differentiated Papillary Mesothelial Tumour (WDPMT) is usually an incidental finding, but rare cases can cause pain. Patients range in age from 23 to 75 years (median: 47 years).
- Micro: WDPMT commonly shows papillary, tubulopapillary, adenomatoid-like areas, and branching cords. A single layer of flattened to cuboidal mesothelial cells with bland nuclei lines the papillae.
- Ancillary: IHC positives include CK7, CK5/6, calretinin, D2-40, HBME1, L1CAM. WDPMT has retained nuclear expression of BAP1.
Reference Gallery:
Well-differentiated papillary mesothelial tumour. The tumour is composed of fibrovascular cores with minimal branching, lined by bland cuboidal cells.
Well-differentiated papillary mesothelial tumour. Diffuse calretinin positivity.
Well-differentiated papillary mesothelial tumour. L1CAM immunohistochemistry demonstrating diffuse strong positive expression in the mesothelial component.
Well-differentiated papillary mesothelial tumour. This tumour demonstrates retained nuclear expression of BAP1.
Well-differentiated papillary mesothelial tumour. L1CAM-positive membranous immunohistochemical staining.
Well-differentiated papillary mesothelial tumour. Intact BAP1 nuclear expression by immunohistochemistry.

Q: Immunohistochemistry for well-differentiated papillary mesothelial tumor characteristically demonstrates diffuse, strong membranous positivity for [...].
Well-differentiated papillary mesothelial tumour. L1CAM immunohistochemistry demonstrating diffuse strong positive expression in the mesothelial component.
Well-differentiated papillary mesothelial tumour. L1CAM-positive membranous immunohistochemical staining.
A: L1CAM
Back Extra: Well-differentiated Papillary Mesothelial Tumour
- Clinical: Well-differentiated Papillary Mesothelial Tumour (WDPMT) is usually an incidental finding, but rare cases can cause pain. Patients range in age from 23 to 75 years (median: 47 years).
- Micro: WDPMT commonly shows papillary, tubulopapillary, adenomatoid-like areas, and branching cords. A single layer of flattened to cuboidal mesothelial cells with bland nuclei lines the papillae.
- Ancillary: IHC positives include CK7, CK5/6, calretinin, D2-40, HBME1, L1CAM. WDPMT has retained nuclear expression of BAP1.
Reference Gallery:
Well-differentiated papillary mesothelial tumour. The tumour is composed of fibrovascular cores with minimal branching, lined by bland cuboidal cells.
Well-differentiated papillary mesothelial tumour. Diffuse calretinin positivity.
Well-differentiated papillary mesothelial tumour. L1CAM immunohistochemistry demonstrating diffuse strong positive expression in the mesothelial component.
Well-differentiated papillary mesothelial tumour. This tumour demonstrates retained nuclear expression of BAP1.
Well-differentiated papillary mesothelial tumour. L1CAM-positive membranous immunohistochemical staining.
Well-differentiated papillary mesothelial tumour. Intact BAP1 nuclear expression by immunohistochemistry.

Q: Unlike many malignant mesotheliomas, well-differentiated papillary mesothelial tumor typically demonstrates [...] nuclear expression of BAP1 by immunohistochemistry.
Well-differentiated papillary mesothelial tumour. This tumour demonstrates retained nuclear expression of BAP1.
Well-differentiated papillary mesothelial tumour. Intact BAP1 nuclear expression by immunohistochemistry.
A: retained
Back Extra: Well-differentiated Papillary Mesothelial Tumour
- Clinical: Well-differentiated Papillary Mesothelial Tumour (WDPMT) is usually an incidental finding, but rare cases can cause pain. Patients range in age from 23 to 75 years (median: 47 years).
- Micro: WDPMT commonly shows papillary, tubulopapillary, adenomatoid-like areas, and branching cords. A single layer of flattened to cuboidal mesothelial cells with bland nuclei lines the papillae.
- Ancillary: IHC positives include CK7, CK5/6, calretinin, D2-40, HBME1, L1CAM. WDPMT has retained nuclear expression of BAP1.
Reference Gallery:
Well-differentiated papillary mesothelial tumour. The tumour is composed of fibrovascular cores with minimal branching, lined by bland cuboidal cells.
Well-differentiated papillary mesothelial tumour. Diffuse calretinin positivity.
Well-differentiated papillary mesothelial tumour. L1CAM immunohistochemistry demonstrating diffuse strong positive expression in the mesothelial component.
Well-differentiated papillary mesothelial tumour. This tumour demonstrates retained nuclear expression of BAP1.
Well-differentiated papillary mesothelial tumour. L1CAM-positive membranous immunohistochemical staining.
Well-differentiated papillary mesothelial tumour. Intact BAP1 nuclear expression by immunohistochemistry.

Q: The most common histologic subtype of Malignant Mesothelioma is the [...] type, which frequently forms tubular, papillary, or solid patterns and shows minimal stratification compared to serous carcinoma.
Peritoneal mesothelioma, epithelioid type. Confluent papillae lined by columnar cells with mild, focally moderate atypia and inconspicuous mitotic activity.
Peritoneal mesothelioma, epithelioid type. The tumour shows papillae lined by a single row of atypical cuboidal cells.
A: epithelioid
Q: Malignant Mesothelioma
- Clinical: The presenting symptoms/signs of [...] are typically nonspecific (abdominal distention or pain, gastrointestinal disturbances, weight loss), but it may be an incidental finding. Ascites is present in most patients.
- Micro: Most [...] tumours are epithelioid, with the most common architectural patterns being tubular, papillary, and solid (often admixed). Minimal stratification and cell budding differentiate it from serous carcinoma.
- Ancillary: Immunohistochemistry (IHC) for [...] is positive for calretinin, WT1, CK5/6, mesothelin, D2-40, and CK7. It is negative for B72.3, BerEP4, claudin-4, MOC31, CD15 (LeuM1), BAP1, ER, and PR.
Reference Gallery:
Peritoneal mesothelioma, biphasic type. This tumour demonstrates unequivocal invasive growth by atypical mesothelial cells.
Peritoneal mesothelioma, epithelioid type. All the malignant cells demonstrate loss of nuclear expression of BAP1. There is preserved positive staining for BAP1 in non-neoplastic cells, which serve as an internal positive control.
Peritoneal mesothelioma, epithelioid type. Confluent papillae lined by columnar cells with mild, focally moderate atypia and inconspicuous mitotic activity.
Peritoneal mesothelioma, epithelioid type. The tumour is calretinin-positive, with nuclear and cytoplasmic staining.
Peritoneal mesothelioma, epithelioid type. The tumour shows positive immunohistochemical cytoplasmic staining for CK5/6.
Peritoneal mesothelioma, epithelioid type. Negative for ER.
Peritoneal mesothelioma, epithelioid type. BerEP4-negative.
Peritoneal mesothelioma, epithelioid type. MOC31-negative.
Peritoneal mesothelioma, sarcomatoid type. There are spindled mesothelial cells growing in a solid pattern.
Peritoneal mesothelioma, biphasic type. The epithelioid component shows confluent papillae.
Peritoneal mesothelioma, biphasic type. The sarcomatoid component shows spindled cells in a diffuse growth pattern.
Peritoneal mesothelioma, epithelioid type. The tumour shows papillae lined by a single row of atypical cuboidal cells.
A: malignant mesothelioma; malignant mesothelioma; malignant mesothelioma

Q: By immunohistochemistry, Malignant Mesothelioma is characteristically positive for mesothelial markers such as WT1, D2-40, CK5/6, and [...], the latter of which shows characteristic both nuclear and cytoplasmic staining.
Peritoneal mesothelioma, epithelioid type. The tumour is calretinin-positive, with nuclear and cytoplasmic staining.
Peritoneal mesothelioma, epithelioid type. The tumour shows positive immunohistochemical cytoplasmic staining for CK5/6.
A: calretinin
Q: Malignant Mesothelioma
- Clinical: The presenting symptoms/signs of [...] are typically nonspecific (abdominal distention or pain, gastrointestinal disturbances, weight loss), but it may be an incidental finding. Ascites is present in most patients.
- Micro: Most [...] tumours are epithelioid, with the most common architectural patterns being tubular, papillary, and solid (often admixed). Minimal stratification and cell budding differentiate it from serous carcinoma.
- Ancillary: Immunohistochemistry (IHC) for [...] is positive for calretinin, WT1, CK5/6, mesothelin, D2-40, and CK7. It is negative for B72.3, BerEP4, claudin-4, MOC31, CD15 (LeuM1), BAP1, ER, and PR.
Reference Gallery:
Peritoneal mesothelioma, biphasic type. This tumour demonstrates unequivocal invasive growth by atypical mesothelial cells.
Peritoneal mesothelioma, epithelioid type. All the malignant cells demonstrate loss of nuclear expression of BAP1. There is preserved positive staining for BAP1 in non-neoplastic cells, which serve as an internal positive control.
Peritoneal mesothelioma, epithelioid type. Confluent papillae lined by columnar cells with mild, focally moderate atypia and inconspicuous mitotic activity.
Peritoneal mesothelioma, epithelioid type. The tumour is calretinin-positive, with nuclear and cytoplasmic staining.
Peritoneal mesothelioma, epithelioid type. The tumour shows positive immunohistochemical cytoplasmic staining for CK5/6.
Peritoneal mesothelioma, epithelioid type. Negative for ER.
Peritoneal mesothelioma, epithelioid type. BerEP4-negative.
Peritoneal mesothelioma, epithelioid type. MOC31-negative.
Peritoneal mesothelioma, sarcomatoid type. There are spindled mesothelial cells growing in a solid pattern.
Peritoneal mesothelioma, biphasic type. The epithelioid component shows confluent papillae.
Peritoneal mesothelioma, biphasic type. The sarcomatoid component shows spindled cells in a diffuse growth pattern.
Peritoneal mesothelioma, epithelioid type. The tumour shows papillae lined by a single row of atypical cuboidal cells.
A: malignant mesothelioma; malignant mesothelioma; malignant mesothelioma

Q: A highly specific immunohistochemical feature that helps confirm a diagnosis of Malignant Mesothelioma and distinguish it from benign reactive mesothelial proliferations is the loss of nuclear expression of [...].
Peritoneal mesothelioma, epithelioid type. All the malignant cells demonstrate loss of nuclear expression of BAP1. There is preserved positive staining for BAP1 in non-neoplastic cells, which serve as an internal positive control.
A: BAP1
Q: Malignant Mesothelioma
- Clinical: The presenting symptoms/signs of [...] are typically nonspecific (abdominal distention or pain, gastrointestinal disturbances, weight loss), but it may be an incidental finding. Ascites is present in most patients.
- Micro: Most [...] tumours are epithelioid, with the most common architectural patterns being tubular, papillary, and solid (often admixed). Minimal stratification and cell budding differentiate it from serous carcinoma.
- Ancillary: Immunohistochemistry (IHC) for [...] is positive for calretinin, WT1, CK5/6, mesothelin, D2-40, and CK7. It is negative for B72.3, BerEP4, claudin-4, MOC31, CD15 (LeuM1), BAP1, ER, and PR.
Reference Gallery:
Peritoneal mesothelioma, biphasic type. This tumour demonstrates unequivocal invasive growth by atypical mesothelial cells.
Peritoneal mesothelioma, epithelioid type. All the malignant cells demonstrate loss of nuclear expression of BAP1. There is preserved positive staining for BAP1 in non-neoplastic cells, which serve as an internal positive control.
Peritoneal mesothelioma, epithelioid type. Confluent papillae lined by columnar cells with mild, focally moderate atypia and inconspicuous mitotic activity.
Peritoneal mesothelioma, epithelioid type. The tumour is calretinin-positive, with nuclear and cytoplasmic staining.
Peritoneal mesothelioma, epithelioid type. The tumour shows positive immunohistochemical cytoplasmic staining for CK5/6.
Peritoneal mesothelioma, epithelioid type. Negative for ER.
Peritoneal mesothelioma, epithelioid type. BerEP4-negative.
Peritoneal mesothelioma, epithelioid type. MOC31-negative.
Peritoneal mesothelioma, sarcomatoid type. There are spindled mesothelial cells growing in a solid pattern.
Peritoneal mesothelioma, biphasic type. The epithelioid component shows confluent papillae.
Peritoneal mesothelioma, biphasic type. The sarcomatoid component shows spindled cells in a diffuse growth pattern.
Peritoneal mesothelioma, epithelioid type. The tumour shows papillae lined by a single row of atypical cuboidal cells.
A: malignant mesothelioma; malignant mesothelioma; malignant mesothelioma

Q: Histologically, Adrenocortical Remnants characteristically form round nests or cords of pale, [...] cells that closely mimic the normal adrenal cortex.
Adrenocortical remnants. The histology mimics that of the cortex of the adrenal gland.
Adrenocortical remnants. There is a round nest of lipid-rich cells within paratubal adipose tissue.
A: lipid-rich
Back Extra: Adrenocortical Remnants
- Clinical: Adrenocortical remnants are typically an incidental finding in about one quarter of thoroughly examined broad ligaments.
- Micro: The remnants form round nests or cords of pale lipid-rich cells resembling the cortex of the adrenal gland.
- Ancillary: Ancillary studies are not typically required for diagnosis.
Reference Gallery:
Adrenocortical remnants. The histology mimics that of the cortex of the adrenal gland.
Adrenocortical remnants. There is a round nest of lipid-rich cells within paratubal adipose tissue.

Q: Adrenocortical Remnants are typically an incidental microscopic finding in about one quarter of thoroughly examined [...].
Adrenocortical remnants. There is a round nest of lipid-rich cells within paratubal adipose tissue.
A: broad ligaments
Back Extra: Adrenocortical Remnants
- Clinical: Adrenocortical remnants are typically an incidental finding in about one quarter of thoroughly examined broad ligaments.
- Micro: The remnants form round nests or cords of pale lipid-rich cells resembling the cortex of the adrenal gland.
- Ancillary: Ancillary studies are not typically required for diagnosis.
Reference Gallery:
Adrenocortical remnants. The histology mimics that of the cortex of the adrenal gland.
Adrenocortical remnants. There is a round nest of lipid-rich cells within paratubal adipose tissue.

Q: Microscopically, an Endometrial Polyp classically features irregularly shaped glands within a hypercellular, fibrous stroma, accompanied by striking, prominent [...].
Endometrial polyp. Glands of various sizes within a hypercellular and fibrous stroma.
Endometrial polyp. The glands are lined by benign and inactive epithelial cells. Stromal thick-walled blood vessels are striking.
A: thick-walled blood vessels
Back Extra: Endometrial Polyp
- Clinical: Common symptoms include abnormal uterine bleeding and infertility, often affecting perimenopausal or postmenopausal women.
- Micro: Microscopically, endometrial polyps show clusters of irregularly shaped glands with a hypercellular and fibrous stroma, and prominent blood vessels.
- Ancillary: Not typically required for diagnosis, but immunohistochemistry may be useful to confirm subtle involvement by serous carcinoma.
Reference Gallery:
Endometrial polyp. Glands of various sizes within a hypercellular and fibrous stroma.
Endometrial polyp. The glands are lined by benign and inactive epithelial cells. Stromal thick-walled blood vessels are striking.

Q: Often presenting with abnormal uterine bleeding, an [...] is diagnosed microscopically by the presence of irregularly shaped glands, a hypercellular and fibrous stroma, and prominent thick-walled blood vessels.
Endometrial polyp. Glands of various sizes within a hypercellular and fibrous stroma.
Endometrial polyp. The glands are lined by benign and inactive epithelial cells. Stromal thick-walled blood vessels are striking.
A: Endometrial Polyp
Back Extra: Endometrial Polyp
- Clinical: Common symptoms include abnormal uterine bleeding and infertility, often affecting perimenopausal or postmenopausal women.
- Micro: Microscopically, endometrial polyps show clusters of irregularly shaped glands with a hypercellular and fibrous stroma, and prominent blood vessels.
- Ancillary: Not typically required for diagnosis, but immunohistochemistry may be useful to confirm subtle involvement by serous carcinoma.
Reference Gallery:
Endometrial polyp. Glands of various sizes within a hypercellular and fibrous stroma.
Endometrial polyp. The glands are lined by benign and inactive epithelial cells. Stromal thick-walled blood vessels are striking.

Q: Exaggerated Placental Site Reaction features intermediate trophoblast and implantation site-type multinucleated giant cells, but unlike placental site trophoblastic tumors, it is characteristically associated with the presence of [...].
Exaggerated placental site reaction. Decidualized stroma and superficial myometrium show a poorly circumscribed, infiltrative lesion comprising individual cells and nests of intermediate trophoblast.
Exaggerated placental site reaction. Implantation site–type multinucleated trophoblast giant cells are characteristically distributed evenly within the lesion. The presence of chorionic villi (not seen in this image) is helpful in differentiating this lesion from placental site trophoblastic tumour.
A: chorionic villi
Back Extra: Exaggerated Placental Site Reaction
- Clinical: Exaggerated placental site reaction is often asymptomatic, but can present with vaginal bleeding, and is associated with normal gestation or hydatidiform mole.
- Micro: The lesion consists of atypical and pleomorphic trophoblastic cells arranged in cords and small nests, with characteristic multinucleated trophoblast giant cells.
- Ancillary: Double MCAM/Ki-67 staining shows virtually no proliferation within the trophoblast, which helps in differentiating it from other trophoblastic tumors.
Reference Gallery:
Exaggerated placental site reaction. Double MCAM/Ki-67 staining shows virtually no proliferation (red, nuclear) within MCAM-lined trophoblast (brown, membranous).
Exaggerated placental site reaction. Decidualized stroma and superficial myometrium show a poorly circumscribed, infiltrative lesion comprising individual cells and nests of intermediate trophoblast.
Exaggerated placental site reaction. Implantation site–type multinucleated trophoblast giant cells are characteristically distributed evenly within the lesion. The presence of chorionic villi (not seen in this image) is helpful in differentiating this lesion from placental site trophoblastic tumour.
Exaggerated placental site reaction. Implantation site–type multinucleated trophoblast giant cells are characteristically distributed evenly within the lesion. Trophoblastic cells may be seen within the vascular spaces, with perivascular fibrinoid necrosis (endovascular plugging).

Q: Exaggerated Placental Site Reaction can be distinguished from trophoblastic tumors using a double [...] stain, which highlights the trophoblast while demonstrating virtually no cellular proliferation.
Exaggerated placental site reaction. Double MCAM/Ki-67 staining shows virtually no proliferation (red, nuclear) within MCAM-lined trophoblast (brown, membranous).
A: MCAM/Ki-67
Back Extra: Exaggerated Placental Site Reaction
- Clinical: Exaggerated placental site reaction is often asymptomatic, but can present with vaginal bleeding, and is associated with normal gestation or hydatidiform mole.
- Micro: The lesion consists of atypical and pleomorphic trophoblastic cells arranged in cords and small nests, with characteristic multinucleated trophoblast giant cells.
- Ancillary: Double MCAM/Ki-67 staining shows virtually no proliferation within the trophoblast, which helps in differentiating it from other trophoblastic tumors.
Reference Gallery:
Exaggerated placental site reaction. Double MCAM/Ki-67 staining shows virtually no proliferation (red, nuclear) within MCAM-lined trophoblast (brown, membranous).
Exaggerated placental site reaction. Decidualized stroma and superficial myometrium show a poorly circumscribed, infiltrative lesion comprising individual cells and nests of intermediate trophoblast.
Exaggerated placental site reaction. Implantation site–type multinucleated trophoblast giant cells are characteristically distributed evenly within the lesion. The presence of chorionic villi (not seen in this image) is helpful in differentiating this lesion from placental site trophoblastic tumour.
Exaggerated placental site reaction. Implantation site–type multinucleated trophoblast giant cells are characteristically distributed evenly within the lesion. Trophoblastic cells may be seen within the vascular spaces, with perivascular fibrinoid necrosis (endovascular plugging).

Q: Exaggerated Placental Site Reaction often features trophoblastic cells within vascular spaces accompanied by perivascular fibrinoid necrosis, a histologic finding known as [...].
Exaggerated placental site reaction. Implantation site–type multinucleated trophoblast giant cells are characteristically distributed evenly within the lesion. Trophoblastic cells may be seen within the vascular spaces, with perivascular fibrinoid necrosis (endovascular plugging).
A: endovascular plugging
Back Extra: Exaggerated Placental Site Reaction
- Clinical: Exaggerated placental site reaction is often asymptomatic, but can present with vaginal bleeding, and is associated with normal gestation or hydatidiform mole.
- Micro: The lesion consists of atypical and pleomorphic trophoblastic cells arranged in cords and small nests, with characteristic multinucleated trophoblast giant cells.
- Ancillary: Double MCAM/Ki-67 staining shows virtually no proliferation within the trophoblast, which helps in differentiating it from other trophoblastic tumors.
Reference Gallery:
Exaggerated placental site reaction. Double MCAM/Ki-67 staining shows virtually no proliferation (red, nuclear) within MCAM-lined trophoblast (brown, membranous).
Exaggerated placental site reaction. Decidualized stroma and superficial myometrium show a poorly circumscribed, infiltrative lesion comprising individual cells and nests of intermediate trophoblast.
Exaggerated placental site reaction. Implantation site–type multinucleated trophoblast giant cells are characteristically distributed evenly within the lesion. The presence of chorionic villi (not seen in this image) is helpful in differentiating this lesion from placental site trophoblastic tumour.
Exaggerated placental site reaction. Implantation site–type multinucleated trophoblast giant cells are characteristically distributed evenly within the lesion. Trophoblastic cells may be seen within the vascular spaces, with perivascular fibrinoid necrosis (endovascular plugging).

Q: Papillary cystadenoma is a benign tumor frequently associated with [...] syndrome.
Papillary cystadenoma in a patient with von Hippel–Lindau syndrome. The tumour exhibits complex papillary architecture and variably hyalinized stromal cores.
A: von Hippel-Lindau
Back Extra: Papillary Cystadenoma
- Clinical: Papillary cystadenoma occurs in adults, often presenting with abdominal pain and is frequently associated with von Hippel–Lindau syndrome.
- Micro: The tumour shows complex tubulopapillary growth with non-ciliated cuboidal or low columnar cells and minimal clear to eosinophilic cytoplasm.
- Ancillary: Immunohistochemistry is positive for CK7, PAX8, PAX2, and CD10, with variable positivity for WT1 and calretinin.
Reference Gallery:
Papillary cystadenoma in a patient with von Hippel–Lindau syndrome. The tumour exhibits complex papillary architecture and variably hyalinized stromal cores.
Papillary cystadenoma in a patient with von Hippel–Lindau syndrome. The cuboidal cells lining papillae are non-ciliated and bland, with minimal eosinophilic cytoplasm.
Papillary cystadenoma in a patient with von Hippel–Lindau syndrome. Variably sized cystic spaces containing papillae. Notice the colloid material in some of the cysts.
Papillary cystadenoma in a patient with von Hippel–Lindau syndrome. Lining epithelium shows cuboidal / low columnar cells with clear cytoplasm and bland nuclei.

Q: Microscopically, [...] exhibits a complex tubulopapillary architecture lined by bland, non-ciliated cuboidal cells with clear to eosinophilic cytoplasm, and variably hyalinized stromal cores.
Papillary cystadenoma in a patient with von Hippel–Lindau syndrome. The cuboidal cells lining papillae are non-ciliated and bland, with minimal eosinophilic cytoplasm.
Papillary cystadenoma in a patient with von Hippel–Lindau syndrome. Lining epithelium shows cuboidal / low columnar cells with clear cytoplasm and bland nuclei.
A: papillary cystadenoma
Back Extra: Papillary Cystadenoma
- Clinical: Papillary cystadenoma occurs in adults, often presenting with abdominal pain and is frequently associated with von Hippel–Lindau syndrome.
- Micro: The tumour shows complex tubulopapillary growth with non-ciliated cuboidal or low columnar cells and minimal clear to eosinophilic cytoplasm.
- Ancillary: Immunohistochemistry is positive for CK7, PAX8, PAX2, and CD10, with variable positivity for WT1 and calretinin.
Reference Gallery:
Papillary cystadenoma in a patient with von Hippel–Lindau syndrome. The tumour exhibits complex papillary architecture and variably hyalinized stromal cores.
Papillary cystadenoma in a patient with von Hippel–Lindau syndrome. The cuboidal cells lining papillae are non-ciliated and bland, with minimal eosinophilic cytoplasm.
Papillary cystadenoma in a patient with von Hippel–Lindau syndrome. Variably sized cystic spaces containing papillae. Notice the colloid material in some of the cysts.
Papillary cystadenoma in a patient with von Hippel–Lindau syndrome. Lining epithelium shows cuboidal / low columnar cells with clear cytoplasm and bland nuclei.

Q: In papillary cystadenoma, the variably sized cystic spaces containing papillae frequently contain eosinophilic [...] material.
Papillary cystadenoma in a patient with von Hippel–Lindau syndrome. Variably sized cystic spaces containing papillae. Notice the colloid material in some of the cysts.
A: colloid
Back Extra: Papillary Cystadenoma
- Clinical: Papillary cystadenoma occurs in adults, often presenting with abdominal pain and is frequently associated with von Hippel–Lindau syndrome.
- Micro: The tumour shows complex tubulopapillary growth with non-ciliated cuboidal or low columnar cells and minimal clear to eosinophilic cytoplasm.
- Ancillary: Immunohistochemistry is positive for CK7, PAX8, PAX2, and CD10, with variable positivity for WT1 and calretinin.
Reference Gallery:
Papillary cystadenoma in a patient with von Hippel–Lindau syndrome. The tumour exhibits complex papillary architecture and variably hyalinized stromal cores.
Papillary cystadenoma in a patient with von Hippel–Lindau syndrome. The cuboidal cells lining papillae are non-ciliated and bland, with minimal eosinophilic cytoplasm.
Papillary cystadenoma in a patient with von Hippel–Lindau syndrome. Variably sized cystic spaces containing papillae. Notice the colloid material in some of the cysts.
Papillary cystadenoma in a patient with von Hippel–Lindau syndrome. Lining epithelium shows cuboidal / low columnar cells with clear cytoplasm and bland nuclei.

Q: Grossly, Carcinosarcoma of the uterine corpus classically presents as a large, intracavitary [...] mass that often fills and expands the endometrial cavity.
Carcinosarcoma. Gross appearance of a uterine carcinosarcoma. A large polypoid mass in the endometrial cavity.
Carcinosarcoma. The tumour is present as a large intracavitary fungating mass.
A: polypoid
Carcinosarcoma of the uterine corpus
- Clinical: Patients with Carcinosarcoma of the uterine corpus usually present with vaginal bleeding, uterine enlargement, or a pelvic mass.
- Micro: The microscopic appearance of Carcinosarcoma of the uterine corpus shows a biphasic pattern with high-grade carcinoma and sarcomatous elements.
- Ancillary: TP53 mutations are found in approximately 90% of Carcinosarcoma of the uterine corpus cases, similar to endometrial serous carcinoma.
Reference Gallery:
Carcinosarcoma. Gross appearance of a uterine carcinosarcoma. A large polypoid mass in the endometrial cavity.
Carcinosarcoma. The tumour shows two malignant components: epithelial and sarcomatous.
Carcinosarcoma. The tumour has a biphasic pattern, with a high-grade epithelial carcinoma component and sarcomatous elements.
Carcinosarcoma. The tumour is present as a large intracavitary fungating mass.
Carcinosarcoma. The tumour is composed of an admixture of high-grade carcinoma closely juxtaposed to a malignant mesenchymal component, which in this example shows heterologous chondrosarcomatous differentiation.

Q: The defining microscopic feature of Carcinosarcoma of the uterine corpus is a [...] pattern, consisting of intimately admixed high-grade carcinoma and malignant mesenchymal (sarcomatous) elements.
Carcinosarcoma. The tumour shows two malignant components: epithelial and sarcomatous.
Carcinosarcoma. The tumour has a biphasic pattern, with a high-grade epithelial carcinoma component and sarcomatous elements.
A: biphasic
Carcinosarcoma of the uterine corpus
- Clinical: Patients with Carcinosarcoma of the uterine corpus usually present with vaginal bleeding, uterine enlargement, or a pelvic mass.
- Micro: The microscopic appearance of Carcinosarcoma of the uterine corpus shows a biphasic pattern with high-grade carcinoma and sarcomatous elements.
- Ancillary: TP53 mutations are found in approximately 90% of Carcinosarcoma of the uterine corpus cases, similar to endometrial serous carcinoma.
Reference Gallery:
Carcinosarcoma. Gross appearance of a uterine carcinosarcoma. A large polypoid mass in the endometrial cavity.
Carcinosarcoma. The tumour shows two malignant components: epithelial and sarcomatous.
Carcinosarcoma. The tumour has a biphasic pattern, with a high-grade epithelial carcinoma component and sarcomatous elements.
Carcinosarcoma. The tumour is present as a large intracavitary fungating mass.
Carcinosarcoma. The tumour is composed of an admixture of high-grade carcinoma closely juxtaposed to a malignant mesenchymal component, which in this example shows heterologous chondrosarcomatous differentiation.

Q: In Carcinosarcoma of the uterine corpus, the malignant mesenchymal component frequently exhibits [...] differentiation, such as forming malignant cartilage (chondrosarcomatous areas) or skeletal muscle.
Carcinosarcoma. The tumour is composed of an admixture of high-grade carcinoma closely juxtaposed to a malignant mesenchymal component, which in this example shows heterologous chondrosarcomatous differentiation.
A: heterologous
Carcinosarcoma of the uterine corpus
- Clinical: Patients with Carcinosarcoma of the uterine corpus usually present with vaginal bleeding, uterine enlargement, or a pelvic mass.
- Micro: The microscopic appearance of Carcinosarcoma of the uterine corpus shows a biphasic pattern with high-grade carcinoma and sarcomatous elements.
- Ancillary: TP53 mutations are found in approximately 90% of Carcinosarcoma of the uterine corpus cases, similar to endometrial serous carcinoma.
Reference Gallery:
Carcinosarcoma. Gross appearance of a uterine carcinosarcoma. A large polypoid mass in the endometrial cavity.
Carcinosarcoma. The tumour shows two malignant components: epithelial and sarcomatous.
Carcinosarcoma. The tumour has a biphasic pattern, with a high-grade epithelial carcinoma component and sarcomatous elements.
Carcinosarcoma. The tumour is present as a large intracavitary fungating mass.
Carcinosarcoma. The tumour is composed of an admixture of high-grade carcinoma closely juxtaposed to a malignant mesenchymal component, which in this example shows heterologous chondrosarcomatous differentiation.

Q: Histologically, Gestational Choriocarcinoma is characterized by highly infiltrative, solid aggregates of mononuclear cytotrophoblasts and intermediate trophoblasts that are classically rimmed by multinucleated [...].
Choriocarcinoma. Biopsy of brain tumour shows metastatic choriocarcinoma with a bilaminar pattern of mononuclear villous cytotrophoblast and intermediate trophoblasts rimmed by multinucleated syncytiotrophoblasts.
Choriocarcinoma. Photomicrograph of a pelvic tumour consistent with recurrent choriocarcinoma. Nodular aggregates of mononuclear and multinucleated trophoblasts are found within fibrin deposits.
Choriocarcinoma. High-power view shows marked cytological atypia, with prominent nucleoli and brisk mitotic activity.
A: syncytiotrophoblasts
Back Extra: Gestational Choriocarcinoma
- Clinical: Common presentations include vaginal bleeding or haemorrhage at ectopic or metastatic sites in association with a highly elevated serum hCG level.
- Micro: Choriocarcinoma is characterized by infiltrative, destructive, solid aggregates of mononuclear villous cytotrophoblast and intermediate trophoblast rimmed by multinucleated syncytiotrophoblast.
- Ancillary: Strong immunoreactivity for hCG, HSD3B1, hPL, inhibin, MCAM, SALL4, HLA-G, MUC4, and p63 in neoplastic syncytiotrophoblasts and in intermediate trophoblasts.
Reference Gallery:
Choriocarcinoma. Biopsy of brain tumour shows metastatic choriocarcinoma with a bilaminar pattern of mononuclear villous cytotrophoblast and intermediate trophoblasts rimmed by multinucleated syncytiotrophoblasts.
Choriocarcinoma. Photomicrograph of a pelvic tumour consistent with recurrent choriocarcinoma. Nodular aggregates of mononuclear and multinucleated trophoblasts are found within fibrin deposits.
Choriocarcinoma. High-power view shows marked cytological atypia, with prominent nucleoli and brisk mitotic activity.
Choriocarcinoma. Immunohistochemistry shows strong immunoreactivity for SALL4.
Choriocarcinoma. Immunohistochemistry for hPL is focal.
Choriocarcinoma. Immunohistochemistry shows strong immunoreactivity for hCG.
Intraplacental choriocarcinoma. High proliferation as indicated by Ki-67 immunoreactivity in foci of intraplacental choriocarcinoma contrasted with the absence of Ki-67 staining of chorionic villi in this term placenta at left margin of photomicrograph.
Intraplacental choriocarcinoma. Intraplacental choriocarcinoma is found in this term placenta with aggregates of trophoblasts with cytological atypia extending from the chorionic villi into the intervillous space.

Q: Immunohistochemical evaluation of Gestational Choriocarcinoma characteristically demonstrates strong immunoreactivity for SALL4 and [...], which correlates with the highly elevated serum levels frequently seen at clinical presentation.
Choriocarcinoma. Immunohistochemistry shows strong immunoreactivity for SALL4.
Choriocarcinoma. Immunohistochemistry shows strong immunoreactivity for hCG.
A: hCG
Back Extra: Gestational Choriocarcinoma
- Clinical: Common presentations include vaginal bleeding or haemorrhage at ectopic or metastatic sites in association with a highly elevated serum hCG level.
- Micro: Choriocarcinoma is characterized by infiltrative, destructive, solid aggregates of mononuclear villous cytotrophoblast and intermediate trophoblast rimmed by multinucleated syncytiotrophoblast.
- Ancillary: Strong immunoreactivity for hCG, HSD3B1, hPL, inhibin, MCAM, SALL4, HLA-G, MUC4, and p63 in neoplastic syncytiotrophoblasts and in intermediate trophoblasts.
Reference Gallery:
Choriocarcinoma. Biopsy of brain tumour shows metastatic choriocarcinoma with a bilaminar pattern of mononuclear villous cytotrophoblast and intermediate trophoblasts rimmed by multinucleated syncytiotrophoblasts.
Choriocarcinoma. Photomicrograph of a pelvic tumour consistent with recurrent choriocarcinoma. Nodular aggregates of mononuclear and multinucleated trophoblasts are found within fibrin deposits.
Choriocarcinoma. High-power view shows marked cytological atypia, with prominent nucleoli and brisk mitotic activity.
Choriocarcinoma. Immunohistochemistry shows strong immunoreactivity for SALL4.
Choriocarcinoma. Immunohistochemistry for hPL is focal.
Choriocarcinoma. Immunohistochemistry shows strong immunoreactivity for hCG.
Intraplacental choriocarcinoma. High proliferation as indicated by Ki-67 immunoreactivity in foci of intraplacental choriocarcinoma contrasted with the absence of Ki-67 staining of chorionic villi in this term placenta at left margin of photomicrograph.
Intraplacental choriocarcinoma. Intraplacental choriocarcinoma is found in this term placenta with aggregates of trophoblasts with cytological atypia extending from the chorionic villi into the intervillous space.

Q: A unique presentation is intraplacental Gestational Choriocarcinoma, which features atypical trophoblasts extending from chorionic villi into the intervillous space with a markedly elevated proliferation index highlighted by [...] staining.
Intraplacental choriocarcinoma. High proliferation as indicated by Ki-67 immunoreactivity in foci of intraplacental choriocarcinoma contrasted with the absence of Ki-67 staining of chorionic villi in this term placenta at left margin of photomicrograph.
Intraplacental choriocarcinoma. Intraplacental choriocarcinoma is found in this term placenta with aggregates of trophoblasts with cytological atypia extending from the chorionic villi into the intervillous space.
A: Ki-67
Back Extra: Gestational Choriocarcinoma
- Clinical: Common presentations include vaginal bleeding or haemorrhage at ectopic or metastatic sites in association with a highly elevated serum hCG level.
- Micro: Choriocarcinoma is characterized by infiltrative, destructive, solid aggregates of mononuclear villous cytotrophoblast and intermediate trophoblast rimmed by multinucleated syncytiotrophoblast.
- Ancillary: Strong immunoreactivity for hCG, HSD3B1, hPL, inhibin, MCAM, SALL4, HLA-G, MUC4, and p63 in neoplastic syncytiotrophoblasts and in intermediate trophoblasts.
Reference Gallery:
Choriocarcinoma. Biopsy of brain tumour shows metastatic choriocarcinoma with a bilaminar pattern of mononuclear villous cytotrophoblast and intermediate trophoblasts rimmed by multinucleated syncytiotrophoblasts.
Choriocarcinoma. Photomicrograph of a pelvic tumour consistent with recurrent choriocarcinoma. Nodular aggregates of mononuclear and multinucleated trophoblasts are found within fibrin deposits.
Choriocarcinoma. High-power view shows marked cytological atypia, with prominent nucleoli and brisk mitotic activity.
Choriocarcinoma. Immunohistochemistry shows strong immunoreactivity for SALL4.
Choriocarcinoma. Immunohistochemistry for hPL is focal.
Choriocarcinoma. Immunohistochemistry shows strong immunoreactivity for hCG.
Intraplacental choriocarcinoma. High proliferation as indicated by Ki-67 immunoreactivity in foci of intraplacental choriocarcinoma contrasted with the absence of Ki-67 staining of chorionic villi in this term placenta at left margin of photomicrograph.
Intraplacental choriocarcinoma. Intraplacental choriocarcinoma is found in this term placenta with aggregates of trophoblasts with cytological atypia extending from the chorionic villi into the intervillous space.

Q: Histologically, Invasive and Metastatic Hydatidiform Moles are typically complete moles characterized by molar villi showing direct [...].
Vascular invasion by complete mole. Uterine subserosal vessel involved by invasive complete mole.
Invasive complete mole. Myometrial invasion by complete mole with molar villi in direct contact with myometrial smooth muscle fibres without intervening decidua.
A: myometrial or vascular invasion
Back Extra: Invasive and Metastatic Hydatidiform Moles
- Clinical: Vaginal bleeding with persistent elevation of serum hCG after primary evacuation of a hydatidiform mole is characteristic.
- Micro: Invasive hydatidiform moles are typically complete moles with villous histological characteristics and evidence of myometrial or vascular invasion.
- Ancillary: Chemotherapy is highly effective, with a cure rate of > 80%, depending on the extent of the disease.
Reference Gallery:
Vascular invasion by complete mole. Uterine subserosal vessel involved by invasive complete mole.
Invasive complete mole. Myometrial invasion by complete mole with molar villi in direct contact with myometrial smooth muscle fibres without intervening decidua.

Q: When evaluating Invasive and Metastatic Hydatidiform Moles for tissue invasion, the molar villi are characteristically seen in direct contact with myometrial smooth muscle fibers without intervening [...].
Invasive complete mole. Myometrial invasion by complete mole with molar villi in direct contact with myometrial smooth muscle fibres without intervening decidua.
A: decidua
Back Extra: Invasive and Metastatic Hydatidiform Moles
- Clinical: Vaginal bleeding with persistent elevation of serum hCG after primary evacuation of a hydatidiform mole is characteristic.
- Micro: Invasive hydatidiform moles are typically complete moles with villous histological characteristics and evidence of myometrial or vascular invasion.
- Ancillary: Chemotherapy is highly effective, with a cure rate of > 80%, depending on the extent of the disease.
Reference Gallery:
Vascular invasion by complete mole. Uterine subserosal vessel involved by invasive complete mole.
Invasive complete mole. Myometrial invasion by complete mole with molar villi in direct contact with myometrial smooth muscle fibres without intervening decidua.

Q: The diagnosis of Mixed Carcinoma of the Uterine Corpus requires the identification of at least two spatially distinct histotypes, most commonly consisting of serous carcinoma and [...] carcinoma.
Endometrial carcinoma with mixed endometrioid and serous patterns. Note a low-grade endometrioid carcinoma (top of field) and a serous carcinoma (bottom of field). Immunohistochemistry is critical for proving that the two tumours are distinct, because the glandular component of a serous carcinoma can appear spuriously low-grade relative to the papillary component.
Endometrial carcinoma with mixed endometrioid and serous patterns. Endometrial carcinoma with mixed endometrioid (left) and serous (right) patterns. This case (also shown in Fig. #13755) shows two separate fragments of tumour with different histomorphological patterns. The fragment to the left shows low-grade endometrioid carcinoma with squamous metaplasia, whereas the fragment to the right shows papillary serous carcinoma.
A: endometrioid
Back Extra: Mixed Carcinoma of the Uterine Corpus
- Clinical: Mixed endometrial carcinomas are rare, accounting for about 10% of all endometrial carcinomas and lack distinctive clinical features.
- Micro: At least two spatially distinct histotypes must be identified, typically endometrioid and serous, with specific immunohistochemical markers confirming the distinct nature of each component.
- Ancillary: Immunohistochemical studies are crucial, showing p53 positivity in the serous component and wildtype p53 in the endometrioid component.
Reference Gallery:
Endometrial carcinoma with mixed endometrioid and serous patterns. Note a low-grade endometrioid carcinoma (top of field) and a serous carcinoma (bottom of field). Immunohistochemistry is critical for proving that the two tumours are distinct, because the glandular component of a serous carcinoma can appear spuriously low-grade relative to the papillary component.
Endometrial carcinoma with mixed endometrioid and serous patterns. Endometrial carcinoma with mixed endometrioid (left) and serous (right) patterns. The serous carcinoma has a glandular pattern, mimicking an endometrioid carcinoma. This is the same case as shown in Fig. #13751, Fig. #13752, and Fig. #13753.
Endometrioid component of mixed endometrioid and serous carcinoma. Higher magnification shows a low nuclear grade, with squamous metaplasia. This is the same case as shown in Fig. #13750, Fig. #13752, and Fig. #13753.
Serous component of mixed endometrioid and serous carcinoma. The serous component shows a high nuclear grade, with prominent nucleoli and high mitotic activity. This is the same case as shown in Fig. #13750, Fig. #13751, and Fig. #13753.
Endometrial carcinoma with mixed endometrioid and serous patterns. Endometrial carcinoma with mixed endometrioid (left) and serous (right) patterns. p53 staining is strongly positive in the serous component and wildtype in the endometrioid component. A transitional staining pattern is seen between the two disparate tumour types. The transition from one tumour type to the other suggests perhaps a transformation from endometrioid to serous carcinoma. This is the same case as shown in Fig. #13750, Fig. #13751, and Fig. #13752.
Endometrial carcinoma with mixed endometrioid and serous patterns. Endometrial carcinoma with mixed endometrioid (left) and serous (right) patterns. This case (also shown in Fig. #13755) shows two separate fragments of tumour with different histomorphological patterns. The fragment to the left shows low-grade endometrioid carcinoma with squamous metaplasia, whereas the fragment to the right shows papillary serous carcinoma.
Endometrial carcinoma with mixed endometrioid and serous patterns. Endometrial carcinoma with mixed endometrioid (left) and serous patterns (right). This case (also shown in Fig. #13754) shows two separate fragments of tumour with different histomorphological patterns. Immunohistochemically, the endometrioid adenocarcinoma shows wildtype p53 staining and the serous carcinoma shows strong diffuse p53 positivity.

Q: Immunohistochemistry is crucial for confirming the distinct components of a Mixed Carcinoma of the Uterine Corpus; typically, the serous component demonstrates strong, mutant-pattern positivity for [...], whereas the endometrioid component displays a wildtype staining pattern.
Endometrial carcinoma with mixed endometrioid and serous patterns. Endometrial carcinoma with mixed endometrioid (left) and serous (right) patterns. p53 staining is strongly positive in the serous component and wildtype in the endometrioid component. A transitional staining pattern is seen between the two disparate tumour types. The transition from one tumour type to the other suggests perhaps a transformation from endometrioid to serous carcinoma. This is the same case as shown in Fig. #13750, Fig. #13751, and Fig. #13752.
Endometrial carcinoma with mixed endometrioid and serous patterns. Endometrial carcinoma with mixed endometrioid (left) and serous patterns (right). This case (also shown in Fig. #13754) shows two separate fragments of tumour with different histomorphological patterns. Immunohistochemically, the endometrioid adenocarcinoma shows wildtype p53 staining and the serous carcinoma shows strong diffuse p53 positivity.
A: p53
Back Extra: Mixed Carcinoma of the Uterine Corpus
- Clinical: Mixed endometrial carcinomas are rare, accounting for about 10% of all endometrial carcinomas and lack distinctive clinical features.
- Micro: At least two spatially distinct histotypes must be identified, typically endometrioid and serous, with specific immunohistochemical markers confirming the distinct nature of each component.
- Ancillary: Immunohistochemical studies are crucial, showing p53 positivity in the serous component and wildtype p53 in the endometrioid component.
Reference Gallery:
Endometrial carcinoma with mixed endometrioid and serous patterns. Note a low-grade endometrioid carcinoma (top of field) and a serous carcinoma (bottom of field). Immunohistochemistry is critical for proving that the two tumours are distinct, because the glandular component of a serous carcinoma can appear spuriously low-grade relative to the papillary component.
Endometrial carcinoma with mixed endometrioid and serous patterns. Endometrial carcinoma with mixed endometrioid (left) and serous (right) patterns. The serous carcinoma has a glandular pattern, mimicking an endometrioid carcinoma. This is the same case as shown in Fig. #13751, Fig. #13752, and Fig. #13753.
Endometrioid component of mixed endometrioid and serous carcinoma. Higher magnification shows a low nuclear grade, with squamous metaplasia. This is the same case as shown in Fig. #13750, Fig. #13752, and Fig. #13753.
Serous component of mixed endometrioid and serous carcinoma. The serous component shows a high nuclear grade, with prominent nucleoli and high mitotic activity. This is the same case as shown in Fig. #13750, Fig. #13751, and Fig. #13753.
Endometrial carcinoma with mixed endometrioid and serous patterns. Endometrial carcinoma with mixed endometrioid (left) and serous (right) patterns. p53 staining is strongly positive in the serous component and wildtype in the endometrioid component. A transitional staining pattern is seen between the two disparate tumour types. The transition from one tumour type to the other suggests perhaps a transformation from endometrioid to serous carcinoma. This is the same case as shown in Fig. #13750, Fig. #13751, and Fig. #13752.
Endometrial carcinoma with mixed endometrioid and serous patterns. Endometrial carcinoma with mixed endometrioid (left) and serous (right) patterns. This case (also shown in Fig. #13755) shows two separate fragments of tumour with different histomorphological patterns. The fragment to the left shows low-grade endometrioid carcinoma with squamous metaplasia, whereas the fragment to the right shows papillary serous carcinoma.
Endometrial carcinoma with mixed endometrioid and serous patterns. Endometrial carcinoma with mixed endometrioid (left) and serous patterns (right). This case (also shown in Fig. #13754) shows two separate fragments of tumour with different histomorphological patterns. Immunohistochemically, the endometrioid adenocarcinoma shows wildtype p53 staining and the serous carcinoma shows strong diffuse p53 positivity.

Q: Microscopically, [...] is characterized by papillary, solid, and tubulocystic architectural patterns, composed of variably pleomorphic cells with clear or eosinophilic cytoplasm.
Clear cell carcinoma. Papillary pattern.
Clear cell carcinoma. Solid pattern.
Clear cell carcinoma. Tubulocystic pattern.
A: Clear Cell Carcinoma of the Uterine Corpus
Q: Clear Cell Carcinoma of the Uterine Corpus
- Clinical: The most frequent presenting symptom of [...] is postmenopausal bleeding, and about 50-60% of the tumours are early-stage at presentation.
- Micro: Diagnostic features include papillary, tubulocystic, and solid architectural patterns with variably pleomorphic polygonal, cuboidal, flat, or hobnail cells with clear or eosinophilic cytoplasm.
- Ancillary: Immunohistochemically, [...] is positive for HNF1β, napsin A, and AMACR, and 22-72% of cases display mutation-pattern p53 staining.
Reference Gallery:
Clear cell carcinoma. Papillary pattern.
Clear cell carcinoma. Solid pattern.
Clear cell carcinoma. Tubulocystic pattern.
A: Clear Cell Carcinoma of the Uterine Corpus; Clear Cell Carcinoma of the Uterine Corpus

Q: In Clear Cell Carcinoma of the Uterine Corpus, the papillary and tubulocystic architectural patterns are frequently lined by characteristic [...] cells with apical nuclei that bulge into the cystic spaces.
Clear cell carcinoma. Papillary pattern.
Clear cell carcinoma. Tubulocystic pattern.
A: hobnail
Q: Clear Cell Carcinoma of the Uterine Corpus
- Clinical: The most frequent presenting symptom of [...] is postmenopausal bleeding, and about 50-60% of the tumours are early-stage at presentation.
- Micro: Diagnostic features include papillary, tubulocystic, and solid architectural patterns with variably pleomorphic polygonal, cuboidal, flat, or hobnail cells with clear or eosinophilic cytoplasm.
- Ancillary: Immunohistochemically, [...] is positive for HNF1β, napsin A, and AMACR, and 22-72% of cases display mutation-pattern p53 staining.
Reference Gallery:
Clear cell carcinoma. Papillary pattern.
Clear cell carcinoma. Solid pattern.
Clear cell carcinoma. Tubulocystic pattern.
A: Clear Cell Carcinoma of the Uterine Corpus; Clear Cell Carcinoma of the Uterine Corpus

Q: Patients with Cowden Syndrome (often presenting with macrocephaly and dermal trichilemmomas) have a 13-19% lifetime risk of developing [...].
Cowden syndrome. Gross appearance of an endometrial carcinoma in a patient with Cowden syndrome.
A: endometrial carcinoma
Back Extra: Cowden Syndrome
- Clinical: Cowden syndrome is characterized by macrocephaly, dermal trichilemmomas, and papillomatous papules, with a lifetime risk of endometrial carcinoma of 13-19%.
- Micro: Uterine carcinomas in Cowden syndrome are usually of the low-grade endometrioid type, but serous endometrial carcinomas may occasionally occur.
- Ancillary: Genetic testing for PTEN mutations is essential for diagnosis, and other genes like SDH, PIK3CA, AKT1, SEC23B, and KLLN may also be involved.
Reference Gallery:
Cowden syndrome. Gross appearance of an endometrial carcinoma in a patient with Cowden syndrome.
Cowden syndrome. Microscopic appearance of a low-grade endometrioid endometrial carcinoma in a patient with Cowden syndrome.

Q: Microscopically, the majority of uterine carcinomas that arise in patients with Cowden Syndrome are of the [...] subtype.
Cowden syndrome. Microscopic appearance of a low-grade endometrioid endometrial carcinoma in a patient with Cowden syndrome.
A: low-grade endometrioid
Back Extra: Cowden Syndrome
- Clinical: Cowden syndrome is characterized by macrocephaly, dermal trichilemmomas, and papillomatous papules, with a lifetime risk of endometrial carcinoma of 13-19%.
- Micro: Uterine carcinomas in Cowden syndrome are usually of the low-grade endometrioid type, but serous endometrial carcinomas may occasionally occur.
- Ancillary: Genetic testing for PTEN mutations is essential for diagnosis, and other genes like SDH, PIK3CA, AKT1, SEC23B, and KLLN may also be involved.
Reference Gallery:
Cowden syndrome. Gross appearance of an endometrial carcinoma in a patient with Cowden syndrome.
Cowden syndrome. Microscopic appearance of a low-grade endometrioid endometrial carcinoma in a patient with Cowden syndrome.

Q: Microscopically, a well-developed Complete Hydatidiform Mole features enlarged, hydropic villi with central [...] formation and marked trophoblastic proliferation.
Complete hydatidiform mole. Well-developed complete mole shows large hydropic villi with cistern formation and circumferential trophoblastic proliferation.
A: cistern
Back Extra: Complete Hydatidiform Mole
- Clinical: Classic symptoms include vaginal bleeding, excessive uterine size, hyperemesis, hyperthyroidism, and pre-eclampsia due to elevated β-hCG levels in patients with a Complete Hydatidiform Mole.
- Micro: Well-developed Complete Hydatidiform Mole is characterized by enlarged, hydropic villi with cistern formation and marked trophoblastic proliferation.
- Ancillary: p57 (KIP2) immunostaining is absent in the cytotrophoblast and villous stromal cells in Complete Hydatidiform Mole, confirming the diagnosis.
Reference Gallery:
Complete hydatidiform mole. Enlarged, hydropic villi are grossly visible in well-developed complete mole.
Complete hydatidiform mole. Well-developed complete mole shows large hydropic villi with cistern formation and circumferential trophoblastic proliferation.
Very early complete hydatidiform mole. Small irregular villi with myxoid stroma and circumferential trophoblastic proliferation.
Complete hydatidiform mole. p57 immunostaining shows absence of nuclear staining in villous stromal cells and cytotrophoblast. Decidua serves as an internal positive control (left side of image).
Very early complete hydatidiform mole. Small irregular villi with myxoid, hypercellular stroma; prominent karyorrhexis; and circumferential trophoblastic proliferation.

Q: The diagnosis of Complete Hydatidiform Mole is confirmed by the absence of nuclear immunostaining for [...] in the cytotrophoblast and villous stromal cells.
Complete hydatidiform mole. p57 immunostaining shows absence of nuclear staining in villous stromal cells and cytotrophoblast. Decidua serves as an internal positive control (left side of image).
A: p57
Back Extra: Complete Hydatidiform Mole
- Clinical: Classic symptoms include vaginal bleeding, excessive uterine size, hyperemesis, hyperthyroidism, and pre-eclampsia due to elevated β-hCG levels in patients with a Complete Hydatidiform Mole.
- Micro: Well-developed Complete Hydatidiform Mole is characterized by enlarged, hydropic villi with cistern formation and marked trophoblastic proliferation.
- Ancillary: p57 (KIP2) immunostaining is absent in the cytotrophoblast and villous stromal cells in Complete Hydatidiform Mole, confirming the diagnosis.
Reference Gallery:
Complete hydatidiform mole. Enlarged, hydropic villi are grossly visible in well-developed complete mole.
Complete hydatidiform mole. Well-developed complete mole shows large hydropic villi with cistern formation and circumferential trophoblastic proliferation.
Very early complete hydatidiform mole. Small irregular villi with myxoid stroma and circumferential trophoblastic proliferation.
Complete hydatidiform mole. p57 immunostaining shows absence of nuclear staining in villous stromal cells and cytotrophoblast. Decidua serves as an internal positive control (left side of image).
Very early complete hydatidiform mole. Small irregular villi with myxoid, hypercellular stroma; prominent karyorrhexis; and circumferential trophoblastic proliferation.

Q: Histologically, both early and well-developed cases of Complete Hydatidiform Mole characteristically exhibit marked, [...] trophoblastic proliferation around the chorionic villi.
Complete hydatidiform mole. Well-developed complete mole shows large hydropic villi with cistern formation and circumferential trophoblastic proliferation.
Very early complete hydatidiform mole. Small irregular villi with myxoid stroma and circumferential trophoblastic proliferation.
A: circumferential
Back Extra: Complete Hydatidiform Mole
- Clinical: Classic symptoms include vaginal bleeding, excessive uterine size, hyperemesis, hyperthyroidism, and pre-eclampsia due to elevated β-hCG levels in patients with a Complete Hydatidiform Mole.
- Micro: Well-developed Complete Hydatidiform Mole is characterized by enlarged, hydropic villi with cistern formation and marked trophoblastic proliferation.
- Ancillary: p57 (KIP2) immunostaining is absent in the cytotrophoblast and villous stromal cells in Complete Hydatidiform Mole, confirming the diagnosis.
Reference Gallery:
Complete hydatidiform mole. Enlarged, hydropic villi are grossly visible in well-developed complete mole.
Complete hydatidiform mole. Well-developed complete mole shows large hydropic villi with cistern formation and circumferential trophoblastic proliferation.
Very early complete hydatidiform mole. Small irregular villi with myxoid stroma and circumferential trophoblastic proliferation.
Complete hydatidiform mole. p57 immunostaining shows absence of nuclear staining in villous stromal cells and cytotrophoblast. Decidua serves as an internal positive control (left side of image).
Very early complete hydatidiform mole. Small irregular villi with myxoid, hypercellular stroma; prominent karyorrhexis; and circumferential trophoblastic proliferation.

Q: In Mesonephric-like Endometrial Adenocarcinoma, the tumor often forms small glands and tubules that classically contain luminal eosinophilic [...].
Mesonephric-like endometrial adenocarcinoma. Small glands and tubules with luminal eosinophilic colloid-like material predominate.
A: colloid-like material
Back Extra: Mesonephric-like Endometrial Adenocarcinoma
- Clinical: Mesonephric-like endometrial adenocarcinomas are rare, representing about 1% of endometrial carcinomas and may arise in the uterine wall.
- Micro: Tumour cells exhibit moderately atypical vesicular nuclei, often with angulation or overlapping, and show a variety of histological patterns including small glands, tubules, papillary, ductal, retiform, solid, or spindled architecture.
- Ancillary: Immunohistochemistry shows typically negative ER and PR, a wildtype pattern of p53 expression, and diffuse GATA3 expression (except in the more solid and spindled areas).
Reference Gallery:
Mesonephric-like endometrial adenocarcinoma. Small glands and tubules with luminal eosinophilic colloid-like material predominate.
Mesonephric-like endometrial adenocarcinoma. Tumour cells have moderately atypical vesicular nuclei, often showing angulation or overlapping.

Q: At high power, the tumor cells of Mesonephric-like Endometrial Adenocarcinoma typically exhibit moderately atypical vesicular nuclei that frequently demonstrate characteristic [...].
Mesonephric-like endometrial adenocarcinoma. Tumour cells have moderately atypical vesicular nuclei, often showing angulation or overlapping.
A: angulation or overlapping
Back Extra: Mesonephric-like Endometrial Adenocarcinoma
- Clinical: Mesonephric-like endometrial adenocarcinomas are rare, representing about 1% of endometrial carcinomas and may arise in the uterine wall.
- Micro: Tumour cells exhibit moderately atypical vesicular nuclei, often with angulation or overlapping, and show a variety of histological patterns including small glands, tubules, papillary, ductal, retiform, solid, or spindled architecture.
- Ancillary: Immunohistochemistry shows typically negative ER and PR, a wildtype pattern of p53 expression, and diffuse GATA3 expression (except in the more solid and spindled areas).
Reference Gallery:
Mesonephric-like endometrial adenocarcinoma. Small glands and tubules with luminal eosinophilic colloid-like material predominate.
Mesonephric-like endometrial adenocarcinoma. Tumour cells have moderately atypical vesicular nuclei, often showing angulation or overlapping.

Q: Microscopically, a Partial Hydatidiform Mole is characteristically composed of [...], presenting as an admixture of small, fibrotic villi alongside enlarged, hydropic villi with cistern formation.
Partial hydatidiform mole. Two villous populations are present: large hydropic villi with cistern formation and small, fibrotic villi.
Partial hydatidiform mole. Irregular villous contours and round to oval trophoblastic pseudoinclusions are characteristic. Note the presence of fetal vessels and rare nucleated red blood cells.
A: two villous populations
Back Extra: Partial Hydatidiform Mole
- Clinical: Patients with partial hydatidiform mole often present in the late first or early second trimester with missed or incomplete abortion.
- Micro: Partial hydatidiform mole shows an admixture of small, fibrotic villi and enlarged, hydropic villi with mild to moderate trophoblastic proliferation.
- Ancillary: Short tandem repeat (STR) DNA genotyping is definitive for identifying diandric triploidy in partial hydatidiform mole.
Reference Gallery:
Partial hydatidiform mole. Two villous populations are present: large hydropic villi with cistern formation and small, fibrotic villi.
Partial hydatidiform mole. Irregular villous contours and round to oval trophoblastic pseudoinclusions are characteristic. Note the presence of fetal vessels and rare nucleated red blood cells.
Dispermic (heterozygous) partial hydatidiform mole. Genotyping shows triploidy of chorionic villous tissue, with two unique paternal alleles () at one short tandem repeat (STR) locus and a unique paternal allele in duplicate quantity (*) at another locus.
Partial hydatidiform mole. Partial hydatidiform mole with mild to moderate circumferential trophoblast hyperplasia, in addition to irregular villous contours and hydrops.
Partial hydatidiform mole. p57 immunostaining shows nuclear staining in villous stromal cells and cytotrophoblast.

Q: Short tandem repeat (STR) DNA genotyping is definitive for diagnosing a Partial Hydatidiform Mole, as it typically identifies [...] (one maternal and two paternal alleles).
Dispermic (heterozygous) partial hydatidiform mole. Genotyping shows triploidy of chorionic villous tissue, with two unique paternal alleles () at one short tandem repeat (STR) locus and a unique paternal allele in duplicate quantity (*) at another locus.
A: diandric triploidy
Back Extra: Partial Hydatidiform Mole
- Clinical: Patients with partial hydatidiform mole often present in the late first or early second trimester with missed or incomplete abortion.
- Micro: Partial hydatidiform mole shows an admixture of small, fibrotic villi and enlarged, hydropic villi with mild to moderate trophoblastic proliferation.
- Ancillary: Short tandem repeat (STR) DNA genotyping is definitive for identifying diandric triploidy in partial hydatidiform mole.
Reference Gallery:
Partial hydatidiform mole. Two villous populations are present: large hydropic villi with cistern formation and small, fibrotic villi.
Partial hydatidiform mole. Irregular villous contours and round to oval trophoblastic pseudoinclusions are characteristic. Note the presence of fetal vessels and rare nucleated red blood cells.
Dispermic (heterozygous) partial hydatidiform mole. Genotyping shows triploidy of chorionic villous tissue, with two unique paternal alleles () at one short tandem repeat (STR) locus and a unique paternal allele in duplicate quantity (*) at another locus.
Partial hydatidiform mole. Partial hydatidiform mole with mild to moderate circumferential trophoblast hyperplasia, in addition to irregular villous contours and hydrops.
Partial hydatidiform mole. p57 immunostaining shows nuclear staining in villous stromal cells and cytotrophoblast.

Q: In a Partial Hydatidiform Mole, immunohistochemistry for [...] demonstrates retained nuclear staining in the villous stromal cells and cytotrophoblasts, helping to distinguish it from a complete hydatidiform mole.
Partial hydatidiform mole. p57 immunostaining shows nuclear staining in villous stromal cells and cytotrophoblast.
A: p57
Back Extra: Partial Hydatidiform Mole
- Clinical: Patients with partial hydatidiform mole often present in the late first or early second trimester with missed or incomplete abortion.
- Micro: Partial hydatidiform mole shows an admixture of small, fibrotic villi and enlarged, hydropic villi with mild to moderate trophoblastic proliferation.
- Ancillary: Short tandem repeat (STR) DNA genotyping is definitive for identifying diandric triploidy in partial hydatidiform mole.
Reference Gallery:
Partial hydatidiform mole. Two villous populations are present: large hydropic villi with cistern formation and small, fibrotic villi.
Partial hydatidiform mole. Irregular villous contours and round to oval trophoblastic pseudoinclusions are characteristic. Note the presence of fetal vessels and rare nucleated red blood cells.
Dispermic (heterozygous) partial hydatidiform mole. Genotyping shows triploidy of chorionic villous tissue, with two unique paternal alleles () at one short tandem repeat (STR) locus and a unique paternal allele in duplicate quantity (*) at another locus.
Partial hydatidiform mole. Partial hydatidiform mole with mild to moderate circumferential trophoblast hyperplasia, in addition to irregular villous contours and hydrops.
Partial hydatidiform mole. p57 immunostaining shows nuclear staining in villous stromal cells and cytotrophoblast.

Q: In Abnormal (non-molar) villous lesions, chorionic villi may show irregularity and enlargement simulating a partial hydatidiform mole, but definitive distinction and detection of aneuploidy is achieved using [...].
Abnormal villous lesion. Non-molar triploid (digynic monoandric) gestation simulating partial hydatidiform mole.
Abnormal villous lesion. Trisomy 18 gestation simulating partial hydatidiform mole.
A: DNA genotyping
Back Extra: Abnormal (non-molar) villous lesions
- Clinical: Clinical features include abortion and abnormal antenatal ultrasound findings.
- Micro: Chorionic villi often display some degree of irregularity in size and shape, with enlargement and focal mild trophoblastic proliferation.
- Ancillary: DNA genotyping analysis effectively distinguishes these lesions from PHM and may detect aneuploid conceptuses.
Reference Gallery:
Abnormal villous lesion. Non-molar triploid (digynic monoandric) gestation simulating partial hydatidiform mole.
Abnormal villous lesion. Trisomy 18 gestation simulating partial hydatidiform mole.
Abnormal villous lesion. Trisomy 21 gestation simulating partial hydatidiform mole.
Abnormal villous lesion. Paternal uniparental isodisomy of chromosome 11, simulating hydatidiform mole.

Q: Microscopically, Abnormal (non-molar) villous lesions may simulate a partial hydatidiform mole due to irregular, enlarged villi, but they typically exhibit only focal and mild [...].
Abnormal villous lesion. Trisomy 21 gestation simulating partial hydatidiform mole.
Abnormal villous lesion. Paternal uniparental isodisomy of chromosome 11, simulating hydatidiform mole.
A: trophoblastic proliferation
Back Extra: Abnormal (non-molar) villous lesions
- Clinical: Clinical features include abortion and abnormal antenatal ultrasound findings.
- Micro: Chorionic villi often display some degree of irregularity in size and shape, with enlargement and focal mild trophoblastic proliferation.
- Ancillary: DNA genotyping analysis effectively distinguishes these lesions from PHM and may detect aneuploid conceptuses.
Reference Gallery:
Abnormal villous lesion. Non-molar triploid (digynic monoandric) gestation simulating partial hydatidiform mole.
Abnormal villous lesion. Trisomy 18 gestation simulating partial hydatidiform mole.
Abnormal villous lesion. Trisomy 21 gestation simulating partial hydatidiform mole.
Abnormal villous lesion. Paternal uniparental isodisomy of chromosome 11, simulating hydatidiform mole.

Q: Microscopically, Placental Site Trophoblastic Tumor exhibits an infiltrative growth pattern where aggregates of intermediate (extravillous) trophoblasts characteristically invade and [...] the myometrial smooth muscle fibers.
Placental site trophoblastic tumour. Low-power view showing infiltrative growth into the myometrium at the periphery of the tumour.
Placental site trophoblastic tumour. High-power view showing intermediate (extravillous trophoblast) infiltrating and splitting apart myometrial fibres. Cells are predominantly mononuclear medium to large polygonal cells, which are occasionally multinuclear. In this case there is abundant eosinophilic cytoplasm, but amphophilic or clear cytoplasm can also be seen. Nuclei are vesicular with clumped chromatin.
A: split apart
Back Extra: Placental Site Trophoblastic Tumour
- Clinical: Placental Site Trophoblastic Tumour commonly presents with vaginal bleeding, uterine enlargement, or a history of missed abortion, following a full-term pregnancy with a median latency of 12–18 months.
- Micro: Characterized by an infiltrative growth pattern with aggregates of large, polyhedral cells that infiltrate and split apart myometrial smooth muscle cells. Marked cytological atypia and pleomorphism are often seen.
- Ancillary: Tumour cells diffusely express hPL, MUC4, HSD3B1, HLA-G, and MCAM (CD146). Ki-67 is expressed in 10–30% of cells.
Reference Gallery:
Placental site trophoblastic tumour. Low-power view showing infiltrative growth into the myometrium at the periphery of the tumour.
Placental site trophoblastic tumour. High-power view showing intermediate (extravillous trophoblast) infiltrating and splitting apart myometrial fibres. Cells are predominantly mononuclear medium to large polygonal cells, which are occasionally multinuclear. In this case there is abundant eosinophilic cytoplasm, but amphophilic or clear cytoplasm can also be seen. Nuclei are vesicular with clumped chromatin.
Placental site trophoblastic tumour. High-power view showing marked cytological atypia and pleomorphism, which can be seen in this neoplasm.
Placental site trophoblastic tumour. High-power view of characteristic vascular invasion. Note that the wall of the vessel has been replaced by intermediate (extravillous) trophoblast.

Q: In Placental Site Trophoblastic Tumor, a characteristic form of vascular invasion occurs where the normal [...] is extensively replaced by intermediate (extravillous) trophoblasts.
Placental site trophoblastic tumour. High-power view of characteristic vascular invasion. Note that the wall of the vessel has been replaced by intermediate (extravillous) trophoblast.
A: vessel wall
Back Extra: Placental Site Trophoblastic Tumour
- Clinical: Placental Site Trophoblastic Tumour commonly presents with vaginal bleeding, uterine enlargement, or a history of missed abortion, following a full-term pregnancy with a median latency of 12–18 months.
- Micro: Characterized by an infiltrative growth pattern with aggregates of large, polyhedral cells that infiltrate and split apart myometrial smooth muscle cells. Marked cytological atypia and pleomorphism are often seen.
- Ancillary: Tumour cells diffusely express hPL, MUC4, HSD3B1, HLA-G, and MCAM (CD146). Ki-67 is expressed in 10–30% of cells.
Reference Gallery:
Placental site trophoblastic tumour. Low-power view showing infiltrative growth into the myometrium at the periphery of the tumour.
Placental site trophoblastic tumour. High-power view showing intermediate (extravillous trophoblast) infiltrating and splitting apart myometrial fibres. Cells are predominantly mononuclear medium to large polygonal cells, which are occasionally multinuclear. In this case there is abundant eosinophilic cytoplasm, but amphophilic or clear cytoplasm can also be seen. Nuclei are vesicular with clumped chromatin.
Placental site trophoblastic tumour. High-power view showing marked cytological atypia and pleomorphism, which can be seen in this neoplasm.
Placental site trophoblastic tumour. High-power view of characteristic vascular invasion. Note that the wall of the vessel has been replaced by intermediate (extravillous) trophoblast.

Q: Microscopically, Serous Carcinoma is characterized by prominent papillary and glandular architectures, conspicuous mitotic activity, and cells with marked nuclear pleomorphism and characteristic [...] features.
Serous carcinoma. Serous carcinoma with papillary and glandular patterns and hobnail features with definitive stromal invasion.
Serous carcinoma. Serous carcinoma with cells exhibiting high-grade cytology, with marked nuclear pleomorphism, macronucleoli, and conspicuous mitotic activity.
A: hobnail
Back Extra: Serous Carcinoma
- Clinical: Most patients with serous carcinoma present with postmenopausal bleeding, and the disease is often associated with extrauterine metastasis.
- Micro: Serous carcinoma is characterized by high-grade cytology, marked nuclear pleomorphism, and prominent mitotic activity.
- Ancillary: TP53 mutations are common in serous carcinoma, and ERBB2 (HER2) overexpression is seen in more than 30% of cases.
Reference Gallery:
Serous carcinoma. Serous carcinoma confined to the glands of an endometrial polyp. The glands are lined by cells with marked cytological atypia, without definitive stromal invasion.
Serous carcinoma. Serous carcinoma with papillary and glandular patterns and hobnail features with definitive stromal invasion.
Serous carcinoma. Serous carcinoma with cells exhibiting high-grade cytology, with marked nuclear pleomorphism, macronucleoli, and conspicuous mitotic activity.

Q: As seen microscopically, early Serous Carcinoma can present with striking cytological atypia confined exclusively to the glands of an [...], lacking definitive stromal invasion.
Serous carcinoma. Serous carcinoma confined to the glands of an endometrial polyp. The glands are lined by cells with marked cytological atypia, without definitive stromal invasion.
A: endometrial polyp
Back Extra: Serous Carcinoma
- Clinical: Most patients with serous carcinoma present with postmenopausal bleeding, and the disease is often associated with extrauterine metastasis.
- Micro: Serous carcinoma is characterized by high-grade cytology, marked nuclear pleomorphism, and prominent mitotic activity.
- Ancillary: TP53 mutations are common in serous carcinoma, and ERBB2 (HER2) overexpression is seen in more than 30% of cases.
Reference Gallery:
Serous carcinoma. Serous carcinoma confined to the glands of an endometrial polyp. The glands are lined by cells with marked cytological atypia, without definitive stromal invasion.
Serous carcinoma. Serous carcinoma with papillary and glandular patterns and hobnail features with definitive stromal invasion.
Serous carcinoma. Serous carcinoma with cells exhibiting high-grade cytology, with marked nuclear pleomorphism, macronucleoli, and conspicuous mitotic activity.

Q: In Undifferentiated and Dedifferentiated Carcinomas of the Ovary, the undifferentiated component typically displays a sheet-like growth of discohesive, monotonous [...], often accompanied by geographical necrosis and prominent tumor-infiltrating lymphocytes.
Ovarian dedifferentiated carcinoma. Large portions of this tumour are undifferentiated; they display sheet-like growth of monotonous round cells. The differentiated component is FIGO grade 1 endometrioid adenocarcinoma. Together, these findings are referred to as “dedifferentiated carcinoma”.
Ovarian undifferentiated carcinoma. The carcinoma consists of sheets of discohesive cells that are small to intermediate in size, with uniform nuclei. This example displays scant cytoplasm.
A: round cells
Back Extra: Undifferentiated and Dedifferentiated Carcinomas of the Ovary
- Clinical: These are highly aggressive neoplasms, typically presenting in advanced stages with bulky pelvic and para-aortic lymph node metastases.
- Micro: The undifferentiated component shows sheet-like growth of monotonous round cells, often with geographical necrosis and prominent tumour-infiltrating lymphocytes.
- Ancillary: IHC reveals loss of SMARCA4 (BRG1), SMARCA2 (BRM), SMARCB1 (INI1), or ARID1A in the undifferentiated areas, and mismatch repair deficiency in about one third of cases.
Reference Gallery:
Ovarian dedifferentiated carcinoma. SMARCA4 (BRG1) loss in the undifferentiated component.
Ovarian dedifferentiated carcinoma. Large portions of this tumour are undifferentiated; they display sheet-like growth of monotonous round cells. The differentiated component is FIGO grade 1 endometrioid adenocarcinoma. Together, these findings are referred to as “dedifferentiated carcinoma”.
Ovarian undifferentiated carcinoma. The carcinoma consists of sheets of discohesive cells that are small to intermediate in size, with uniform nuclei. This example displays scant cytoplasm.

Q: Ancillary testing in Undifferentiated and Dedifferentiated Carcinomas of the Ovary frequently reveals the diagnostic loss of SWI/SNF chromatin remodeling complex proteins in the undifferentiated areas, most notably [...], SMARCA2, SMARCB1, or ARID1A.
Ovarian dedifferentiated carcinoma. SMARCA4 (BRG1) loss in the undifferentiated component.
A: SMARCA4 (BRG1)
Back Extra: Undifferentiated and Dedifferentiated Carcinomas of the Ovary
- Clinical: These are highly aggressive neoplasms, typically presenting in advanced stages with bulky pelvic and para-aortic lymph node metastases.
- Micro: The undifferentiated component shows sheet-like growth of monotonous round cells, often with geographical necrosis and prominent tumour-infiltrating lymphocytes.
- Ancillary: IHC reveals loss of SMARCA4 (BRG1), SMARCA2 (BRM), SMARCB1 (INI1), or ARID1A in the undifferentiated areas, and mismatch repair deficiency in about one third of cases.
Reference Gallery:
Ovarian dedifferentiated carcinoma. SMARCA4 (BRG1) loss in the undifferentiated component.
Ovarian dedifferentiated carcinoma. Large portions of this tumour are undifferentiated; they display sheet-like growth of monotonous round cells. The differentiated component is FIGO grade 1 endometrioid adenocarcinoma. Together, these findings are referred to as “dedifferentiated carcinoma”.
Ovarian undifferentiated carcinoma. The carcinoma consists of sheets of discohesive cells that are small to intermediate in size, with uniform nuclei. This example displays scant cytoplasm.

Q: Histologically, the dedifferentiated pattern of Undifferentiated and Dedifferentiated Carcinomas of the Uterine Corpus is characterized by an abruptly transitioning or admixed undifferentiated tumor and a [...] component (most commonly endometrioid adenocarcinoma).
Dedifferentiated endometrial carcinoma. The tumour shows demarcated differentiated and dedifferentiated areas.
Dedifferentiated endometrial carcinoma. The tumour shows admixed endometrioid and undifferentiated components.
A: differentiated
Back Extra: Undifferentiated and Dedifferentiated Carcinomas of the Uterine Corpus
- Clinical: Most patients are perimenopausal or postmenopausal, often presenting with postmenopausal bleeding and occasionally abdominal pain.
- Micro: Monomorphic undifferentiated carcinoma is characterized by small, discohesive cells with frequent mitotic figures and geographical necrosis. Dedifferentiated carcinoma shows a mix of differentiated and undifferentiated components.
- Ancillary: Immunohistochemistry often shows negative or focal staining for PAX8 and keratin, and frequent loss of SMARCA4 expression.
Reference Gallery:
Dedifferentiated endometrial carcinoma. The tumour shows demarcated differentiated and dedifferentiated areas.
Dedifferentiated endometrial carcinoma. High-power view showing small round cells in the undifferentiated component.
Dedifferentiated endometrial carcinoma. High-power view showing rhabdoid features.
Dedifferentiated endometrial carcinoma. The tumour shows admixed endometrioid and undifferentiated components.

Q: The undifferentiated component of Undifferentiated and Dedifferentiated Carcinomas of the Uterine Corpus typically forms solid sheets of small, discohesive cells that can occasionally exhibit eccentric eosinophilic cytoplasm known as [...] features.
Dedifferentiated endometrial carcinoma. High-power view showing small round cells in the undifferentiated component.
Dedifferentiated endometrial carcinoma. High-power view showing rhabdoid features.
A: rhabdoid
Back Extra: Undifferentiated and Dedifferentiated Carcinomas of the Uterine Corpus
- Clinical: Most patients are perimenopausal or postmenopausal, often presenting with postmenopausal bleeding and occasionally abdominal pain.
- Micro: Monomorphic undifferentiated carcinoma is characterized by small, discohesive cells with frequent mitotic figures and geographical necrosis. Dedifferentiated carcinoma shows a mix of differentiated and undifferentiated components.
- Ancillary: Immunohistochemistry often shows negative or focal staining for PAX8 and keratin, and frequent loss of SMARCA4 expression.
Reference Gallery:
Dedifferentiated endometrial carcinoma. The tumour shows demarcated differentiated and dedifferentiated areas.
Dedifferentiated endometrial carcinoma. High-power view showing small round cells in the undifferentiated component.
Dedifferentiated endometrial carcinoma. High-power view showing rhabdoid features.
Dedifferentiated endometrial carcinoma. The tumour shows admixed endometrioid and undifferentiated components.

Q: Microscopically, Endometrial Atypical Hyperplasia / Endometrioid Intraepithelial Neoplasia is defined by crowded aggregates of altered tubular or branching glands where the volume of glands exceeds the volume of [...], creating a distinct geographical region.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. Densely packed endometrial glands with little intervening stroma, forming a lesion.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. The geographical region of this endometrioid intraepithelial neoplasia lesion is visible at low magnification: its architecture shows aggregates of glands that exceed the volume of stroma.
A: stroma
Back Extra: Endometrial Atypical Hyperplasia / Endometrioid Intraepithelial Neoplasia
- Clinical: Postmenopausal or perimenopausal bleeding is the most common presenting symptom; hereditary susceptibility parallels that of heritable syndromes associated with increased risk for endometrioid endometrial carcinoma, including Cowden syndrome and Lynch syndrome.
- Micro: EAH/EIN is characterized by crowded aggregates of altered tubular or branching glands, with a reduction of the stromal volume. The lesion must be of sufficient size that artefact can be excluded and coincident change of architectural and cytological alterations is evident.
- Ancillary: Loss of immunoreactivity for PTEN, PAX2, or mismatch repair proteins may be a helpful diagnostic tool. EAH/EIN contains many of the genetic changes seen in endometrioid endometrial carcinoma, including microsatellite instability, PAX2 inactivation, and PTEN, KRAS, and CTNNB1 mutations.
Reference Gallery:
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. Densely packed endometrial glands with little intervening stroma, forming a lesion.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. The nuclear and cytoplasmic features of the crowded glands differ from those of the entrapped non-atypical gland in the centre. Cellular atypia is characterized by loss of polarity of the glandular epithelium. The nuclei are irregularly distributed, enlarged, and often vesicular, or they may show distinct nucleoli.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia with secretory changes. The crowded glands show secretory changes, similar to early secretory-phase endometrium. The lesion is distinct from adjacent non-lesional glands, which lack these extensive secretory changes.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia with secretory changes. The atypical glands are characterized by extensive cytoplasmic clearing and enlarged, irregularly distributed nuclei, frequently with distinct nucleoli.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. The atypical gland with enlarged, irregularly distributed, round to oval nuclei (left) is distinct from an adjacent non-lesional gland with smaller, elongated, and pseudostratified nuclei (right).
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia with secretory changes. A lesion consisting of crowded glands with cytoplasmic clearing, distinct from a few adjacent non-lesional glands (top left and right).
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. The geographical region of this endometrioid intraepithelial neoplasia lesion is visible at low magnification: its architecture shows aggregates of glands that exceed the volume of stroma.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. Within the crowded focus, the nuclear and cytoplasmic features of the atypical glands differ from those of the low-density background glands.

Q: In Endometrial Atypical Hyperplasia / Endometrioid Intraepithelial Neoplasia, the atypical glands show cytologic alterations that are distinctly different from the entrapped background glands, often characterized by enlarged, vesicular nuclei with a [...] of the glandular epithelium.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. The nuclear and cytoplasmic features of the crowded glands differ from those of the entrapped non-atypical gland in the centre. Cellular atypia is characterized by loss of polarity of the glandular epithelium. The nuclei are irregularly distributed, enlarged, and often vesicular, or they may show distinct nucleoli.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. The atypical gland with enlarged, irregularly distributed, round to oval nuclei (left) is distinct from an adjacent non-lesional gland with smaller, elongated, and pseudostratified nuclei (right).
A: loss of polarity
Back Extra: Endometrial Atypical Hyperplasia / Endometrioid Intraepithelial Neoplasia
- Clinical: Postmenopausal or perimenopausal bleeding is the most common presenting symptom; hereditary susceptibility parallels that of heritable syndromes associated with increased risk for endometrioid endometrial carcinoma, including Cowden syndrome and Lynch syndrome.
- Micro: EAH/EIN is characterized by crowded aggregates of altered tubular or branching glands, with a reduction of the stromal volume. The lesion must be of sufficient size that artefact can be excluded and coincident change of architectural and cytological alterations is evident.
- Ancillary: Loss of immunoreactivity for PTEN, PAX2, or mismatch repair proteins may be a helpful diagnostic tool. EAH/EIN contains many of the genetic changes seen in endometrioid endometrial carcinoma, including microsatellite instability, PAX2 inactivation, and PTEN, KRAS, and CTNNB1 mutations.
Reference Gallery:
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. Densely packed endometrial glands with little intervening stroma, forming a lesion.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. The nuclear and cytoplasmic features of the crowded glands differ from those of the entrapped non-atypical gland in the centre. Cellular atypia is characterized by loss of polarity of the glandular epithelium. The nuclei are irregularly distributed, enlarged, and often vesicular, or they may show distinct nucleoli.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia with secretory changes. The crowded glands show secretory changes, similar to early secretory-phase endometrium. The lesion is distinct from adjacent non-lesional glands, which lack these extensive secretory changes.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia with secretory changes. The atypical glands are characterized by extensive cytoplasmic clearing and enlarged, irregularly distributed nuclei, frequently with distinct nucleoli.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. The atypical gland with enlarged, irregularly distributed, round to oval nuclei (left) is distinct from an adjacent non-lesional gland with smaller, elongated, and pseudostratified nuclei (right).
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia with secretory changes. A lesion consisting of crowded glands with cytoplasmic clearing, distinct from a few adjacent non-lesional glands (top left and right).
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. The geographical region of this endometrioid intraepithelial neoplasia lesion is visible at low magnification: its architecture shows aggregates of glands that exceed the volume of stroma.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. Within the crowded focus, the nuclear and cytoplasmic features of the atypical glands differ from those of the low-density background glands.

Q: Endometrial Atypical Hyperplasia / Endometrioid Intraepithelial Neoplasia can occasionally feature crowded atypical glands with prominent [...] changes, characterized by extensive cytoplasmic clearing that mimics early secretory-phase endometrium but remains distinct from the adjacent background glands.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia with secretory changes. The crowded glands show secretory changes, similar to early secretory-phase endometrium. The lesion is distinct from adjacent non-lesional glands, which lack these extensive secretory changes.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia with secretory changes. The atypical glands are characterized by extensive cytoplasmic clearing and enlarged, irregularly distributed nuclei, frequently with distinct nucleoli.
A: secretory
Back Extra: Endometrial Atypical Hyperplasia / Endometrioid Intraepithelial Neoplasia
- Clinical: Postmenopausal or perimenopausal bleeding is the most common presenting symptom; hereditary susceptibility parallels that of heritable syndromes associated with increased risk for endometrioid endometrial carcinoma, including Cowden syndrome and Lynch syndrome.
- Micro: EAH/EIN is characterized by crowded aggregates of altered tubular or branching glands, with a reduction of the stromal volume. The lesion must be of sufficient size that artefact can be excluded and coincident change of architectural and cytological alterations is evident.
- Ancillary: Loss of immunoreactivity for PTEN, PAX2, or mismatch repair proteins may be a helpful diagnostic tool. EAH/EIN contains many of the genetic changes seen in endometrioid endometrial carcinoma, including microsatellite instability, PAX2 inactivation, and PTEN, KRAS, and CTNNB1 mutations.
Reference Gallery:
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. Densely packed endometrial glands with little intervening stroma, forming a lesion.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. The nuclear and cytoplasmic features of the crowded glands differ from those of the entrapped non-atypical gland in the centre. Cellular atypia is characterized by loss of polarity of the glandular epithelium. The nuclei are irregularly distributed, enlarged, and often vesicular, or they may show distinct nucleoli.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia with secretory changes. The crowded glands show secretory changes, similar to early secretory-phase endometrium. The lesion is distinct from adjacent non-lesional glands, which lack these extensive secretory changes.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia with secretory changes. The atypical glands are characterized by extensive cytoplasmic clearing and enlarged, irregularly distributed nuclei, frequently with distinct nucleoli.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. The atypical gland with enlarged, irregularly distributed, round to oval nuclei (left) is distinct from an adjacent non-lesional gland with smaller, elongated, and pseudostratified nuclei (right).
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia with secretory changes. A lesion consisting of crowded glands with cytoplasmic clearing, distinct from a few adjacent non-lesional glands (top left and right).
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. The geographical region of this endometrioid intraepithelial neoplasia lesion is visible at low magnification: its architecture shows aggregates of glands that exceed the volume of stroma.
Endometrial atypical hyperplasia / endometrioid intraepithelial neoplasia. Within the crowded focus, the nuclear and cytoplasmic features of the atypical glands differ from those of the low-density background glands.

Q: Histologically, an endometrium displaying increased gland density with branched and cystically dilated glands, but lined by uniform cells lacking nuclear atypia, is diagnostic of [...].
Hyperplasia without atypia. Architectural changes include glandular branching, cysts, and crowding.
Endometrial hyperplasia without atypia. Note the architectural changes (branched and dilated glands) and decreased amount of stroma between the glands.
Endometrial hyperplasia without atypia. The endometrial glands are branched and dilated. The glandular epithelium lacks cellular atypia.
A: Endometrial Hyperplasia without Atypia
Back Extra: Endometrial Hyperplasia without Atypia
- Clinical: Commonly diagnosed in perimenopause, presenting with abnormal, non-cyclical vaginal bleeding and increased endometrial thickness on ultrasound.
- Micro: Tubular glands admixed with branching and cystically dilated glands, creating increased gland density. Epithelium is simple with staggered nuclei creating a pseudostratified appearance.
- Ancillary: Not clinically relevant; diagnosis is primarily histopathological.
Reference Gallery:
Hyperplasia without atypia. Architectural changes include glandular branching, cysts, and crowding.
Hyperplasia without atypia. Cells lining the glands are columnar and pseudostratified, with cigar-shaped nuclei oriented perpendicular to the basement membrane.
Endometrial hyperplasia without atypia. Note the architectural changes (branched and dilated glands) and decreased amount of stroma between the glands.
Endometrial hyperplasia without atypia. The endometrial glands are branched and dilated. The glandular epithelium lacks cellular atypia.
Endometrial hyperplasia without atypia. The endometrial glands are branched and dilated. The stroma between the glands is slightly reduced.
Endometrial hyperplasia without atypia. Note the dilated endometrial glands with artificial intraluminal papillae (the telescope phenomenon).

Q: In Endometrial Hyperplasia without Atypia, the glandular epithelium lacks true atypia and instead maintains uniform, columnar cells with staggered, cigar-shaped nuclei that create a [...] appearance.
Hyperplasia without atypia. Cells lining the glands are columnar and pseudostratified, with cigar-shaped nuclei oriented perpendicular to the basement membrane.
A: pseudostratified
Back Extra: Endometrial Hyperplasia without Atypia
- Clinical: Commonly diagnosed in perimenopause, presenting with abnormal, non-cyclical vaginal bleeding and increased endometrial thickness on ultrasound.
- Micro: Tubular glands admixed with branching and cystically dilated glands, creating increased gland density. Epithelium is simple with staggered nuclei creating a pseudostratified appearance.
- Ancillary: Not clinically relevant; diagnosis is primarily histopathological.
Reference Gallery:
Hyperplasia without atypia. Architectural changes include glandular branching, cysts, and crowding.
Hyperplasia without atypia. Cells lining the glands are columnar and pseudostratified, with cigar-shaped nuclei oriented perpendicular to the basement membrane.
Endometrial hyperplasia without atypia. Note the architectural changes (branched and dilated glands) and decreased amount of stroma between the glands.
Endometrial hyperplasia without atypia. The endometrial glands are branched and dilated. The glandular epithelium lacks cellular atypia.
Endometrial hyperplasia without atypia. The endometrial glands are branched and dilated. The stroma between the glands is slightly reduced.
Endometrial hyperplasia without atypia. Note the dilated endometrial glands with artificial intraluminal papillae (the telescope phenomenon).

Q: In Endometrial Hyperplasia without Atypia, dilated glands may sometimes contain artificial intraluminal papillae, an architectural artifact referred to as the [...] phenomenon.
Endometrial hyperplasia without atypia. Note the dilated endometrial glands with artificial intraluminal papillae (the telescope phenomenon).
A: telescope
Back Extra: Endometrial Hyperplasia without Atypia
- Clinical: Commonly diagnosed in perimenopause, presenting with abnormal, non-cyclical vaginal bleeding and increased endometrial thickness on ultrasound.
- Micro: Tubular glands admixed with branching and cystically dilated glands, creating increased gland density. Epithelium is simple with staggered nuclei creating a pseudostratified appearance.
- Ancillary: Not clinically relevant; diagnosis is primarily histopathological.
Reference Gallery:
Hyperplasia without atypia. Architectural changes include glandular branching, cysts, and crowding.
Hyperplasia without atypia. Cells lining the glands are columnar and pseudostratified, with cigar-shaped nuclei oriented perpendicular to the basement membrane.
Endometrial hyperplasia without atypia. Note the architectural changes (branched and dilated glands) and decreased amount of stroma between the glands.
Endometrial hyperplasia without atypia. The endometrial glands are branched and dilated. The glandular epithelium lacks cellular atypia.
Endometrial hyperplasia without atypia. The endometrial glands are branched and dilated. The stroma between the glands is slightly reduced.
Endometrial hyperplasia without atypia. Note the dilated endometrial glands with artificial intraluminal papillae (the telescope phenomenon).

Q: The most frequently reported subtype of Germ Cell Tumours of the Uterine Corpus is the [...], which often presents with elevated serum AFP and microscopically features papillary structures lined by primitive-appearing cells with characteristic supranuclear and/or subnuclear vacuolization.
Endometrial yolk sac tumour. The tumour exhibits a predominant papillary architectural pattern; papillary structures are lined by cuboidal to columnar cells with primitive-appearing nuclei; supranuclear and/or subnuclear vacuolization is present.
Endometrial yolk sac tumour. The tumour exhibits a predominant papillary architectural pattern; at higher power, papillary structures are lined by cuboidal to columnar cells with primitive-appearing nuclei; supranuclear and/or subnuclear vacuolization is present.
A: yolk sac tumor
Back Extra: Germ Cell Tumours of the Uterine Corpus
- Clinical: Uterine germ cell tumours occur over a wide patient age range (24–87 years), with most cases diagnosed after menopause, typically after presentation for abnormal uterine bleeding. Elevated serum AFP has been reported in uterine yolk sac tumour (YST).
- Micro: YST and immature/mature teratoma have been reported in the uterus. YST is more frequent and often has an associated somatic carcinoma or carcinosarcoma. The histological features of the germ cell component are identical to those of their ovarian counterparts.
- Ancillary: Essential for diagnosis are characteristic microscopic and immunohistochemical features, similar to those seen in ovarian germ cell tumours. Molecular and genetic studies are not clinically relevant.
Reference Gallery:
Endometrial yolk sac tumour. The tumour exhibits a predominant papillary architectural pattern; papillary structures are lined by cuboidal to columnar cells with primitive-appearing nuclei; supranuclear and/or subnuclear vacuolization is present.
Endometrial yolk sac tumour. The tumour exhibits a predominant papillary architectural pattern; at higher power, papillary structures are lined by cuboidal to columnar cells with primitive-appearing nuclei; supranuclear and/or subnuclear vacuolization is present.

Q: An ovarian neoplasm demonstrating two or more malignant germ cell components—such as the intimately admixed immature teratoma, embryonal carcinoma, and yolk sac tumor seen here—is diagnostic for a [...].
Mixed germ cell tumour. Mixed germ cell tumour containing immature teratoma (neuroectodermal rosettes composed of primitive cells), embryonal carcinoma (glandular proliferation of highly atypical cells), and yolk sac tumour (microcystic pattern).
A: Mixed Germ Cell Tumor of the Ovary
Back Extra: Mixed Germ Cell Tumour of the Ovary
- Clinical: Mixed germ cell tumour of the ovary presents with abdominal pain, abdominal mass, and menstrual disorders. Serum markers like LDH, β-hCG, or AFP can be elevated.
- Micro: The tumour contains two or more malignant germ cell components, often including dysgerminoma, yolk sac tumour, and embryonal carcinoma, with components often intimately admixed or present in separate areas.
- Ancillary: Many mixed germ cell tumours exhibit a gain of 12p or isochromosome 12p. Some arise in a gonadoblastoma in patients with a normal or abnormal karyotype.
Reference Gallery:
Mixed germ cell tumour. Mixed germ cell tumour containing immature teratoma (neuroectodermal rosettes composed of primitive cells), embryonal carcinoma (glandular proliferation of highly atypical cells), and yolk sac tumour (microcystic pattern).

Q: Histopathology showing the presence of discrete, admixed areas of choriocarcinoma, placental site trophoblastic tumor (PSTT), and/or epithelioid trophoblastic tumor (ETT) is diagnostic of a [...].
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Low-power view of the placental site trophoblastic tumour component (lower) and epithelioid trophoblastic tumour (upper).
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). Low-power view with choriocarcinoma in the lower-right corner gradually merging with epithelioid trophoblastic tumour in the upper left. Choriocarcinoma is present as sheets of pleomorphic tumour and epithelioid trophoblastic tumour is present in the form of nests with eosinophilic hyaline-like material.
A: Mixed Trophoblastic Tumor
Back Extra: Mixed Trophoblastic Tumour
- Clinical: Abnormal vaginal bleeding is the presenting symptom in more than half of cases of mixed trophoblastic tumour.
- Micro: Histopathology shows the presence of discrete areas of choriocarcinoma, placental site trophoblastic tumour (PSTT), and/or epithelioid trophoblastic tumour (ETT) with characteristic histomorphology of each subtype.
- Ancillary: Positive immunostaining for p63 in the epithelioid trophoblastic tumour component and heavy cytoplasmic staining for hCG in the choriocarcinoma component are key findings.
Reference Gallery:
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Medium-power view of the placental site trophoblastic tumour component.
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Medium-power view of the epithelioid trophoblastic tumour component.
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Negative immunostaining for p63 in the placental site trophoblastic tumour component.
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Positive immunostaining for p63 in the epithelioid trophoblastic tumour component.
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Low-power view of the placental site trophoblastic tumour component (lower) and epithelioid trophoblastic tumour (upper).
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). Low-power view with choriocarcinoma in the lower-right corner gradually merging with epithelioid trophoblastic tumour in the upper left. Choriocarcinoma is present as sheets of pleomorphic tumour and epithelioid trophoblastic tumour is present in the form of nests with eosinophilic hyaline-like material.
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). Choriocarcinoma comprising a haemorrhagic solid destructive mass with biphasic proliferation of pleomorphic mononuclear intermediate/cytotrophoblastic cells rimmed by multinucleated syncytiotrophoblasts.
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). Epithelioid trophoblastic tumour showing a nodular growth pattern, with relatively uniform, medium-sized tumour cells; clear to eosinophilic cytoplasm; and bland-appearing nuclei. Eosinophilic hyalinized material simulating keratinizing squamous cell carcinoma is seen within these nests.
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). Nests of epithelioid trophoblastic tumour (left) are strongly positive with p63, whereas sheets of choriocarcinoma (right) show minimal nuclear staining.
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). There is heavy cytoplasmic staining for hCG in the choriocarcinoma component (right), whereas very few cells show hCG expression in the epithelioid trophoblastic tumour component (left).

Q: In a Mixed Trophoblastic Tumor, the epithelioid trophoblastic tumor (ETT) component characteristically demonstrates strong nuclear immunostaining for [...], which helps distinguish it from the negative choriocarcinoma and placental site trophoblastic tumor (PSTT) components.
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Negative immunostaining for p63 in the placental site trophoblastic tumour component.
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Positive immunostaining for p63 in the epithelioid trophoblastic tumour component.
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). Nests of epithelioid trophoblastic tumour (left) are strongly positive with p63, whereas sheets of choriocarcinoma (right) show minimal nuclear staining.
A: p63
Back Extra: Mixed Trophoblastic Tumour
- Clinical: Abnormal vaginal bleeding is the presenting symptom in more than half of cases of mixed trophoblastic tumour.
- Micro: Histopathology shows the presence of discrete areas of choriocarcinoma, placental site trophoblastic tumour (PSTT), and/or epithelioid trophoblastic tumour (ETT) with characteristic histomorphology of each subtype.
- Ancillary: Positive immunostaining for p63 in the epithelioid trophoblastic tumour component and heavy cytoplasmic staining for hCG in the choriocarcinoma component are key findings.
Reference Gallery:
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Medium-power view of the placental site trophoblastic tumour component.
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Medium-power view of the epithelioid trophoblastic tumour component.
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Negative immunostaining for p63 in the placental site trophoblastic tumour component.
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Positive immunostaining for p63 in the epithelioid trophoblastic tumour component.
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Low-power view of the placental site trophoblastic tumour component (lower) and epithelioid trophoblastic tumour (upper).
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). Low-power view with choriocarcinoma in the lower-right corner gradually merging with epithelioid trophoblastic tumour in the upper left. Choriocarcinoma is present as sheets of pleomorphic tumour and epithelioid trophoblastic tumour is present in the form of nests with eosinophilic hyaline-like material.
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). Choriocarcinoma comprising a haemorrhagic solid destructive mass with biphasic proliferation of pleomorphic mononuclear intermediate/cytotrophoblastic cells rimmed by multinucleated syncytiotrophoblasts.
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). Epithelioid trophoblastic tumour showing a nodular growth pattern, with relatively uniform, medium-sized tumour cells; clear to eosinophilic cytoplasm; and bland-appearing nuclei. Eosinophilic hyalinized material simulating keratinizing squamous cell carcinoma is seen within these nests.
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). Nests of epithelioid trophoblastic tumour (left) are strongly positive with p63, whereas sheets of choriocarcinoma (right) show minimal nuclear staining.
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). There is heavy cytoplasmic staining for hCG in the choriocarcinoma component (right), whereas very few cells show hCG expression in the epithelioid trophoblastic tumour component (left).

Q: When evaluating a Mixed Trophoblastic Tumor, the choriocarcinoma component typically shows heavy cytoplasmic immunostaining for [...], whereas the epithelioid trophoblastic tumor (ETT) component is largely negative.
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). There is heavy cytoplasmic staining for hCG in the choriocarcinoma component (right), whereas very few cells show hCG expression in the epithelioid trophoblastic tumour component (left).
A: hCG
Back Extra: Mixed Trophoblastic Tumour
- Clinical: Abnormal vaginal bleeding is the presenting symptom in more than half of cases of mixed trophoblastic tumour.
- Micro: Histopathology shows the presence of discrete areas of choriocarcinoma, placental site trophoblastic tumour (PSTT), and/or epithelioid trophoblastic tumour (ETT) with characteristic histomorphology of each subtype.
- Ancillary: Positive immunostaining for p63 in the epithelioid trophoblastic tumour component and heavy cytoplasmic staining for hCG in the choriocarcinoma component are key findings.
Reference Gallery:
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Medium-power view of the placental site trophoblastic tumour component.
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Medium-power view of the epithelioid trophoblastic tumour component.
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Negative immunostaining for p63 in the placental site trophoblastic tumour component.
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Positive immunostaining for p63 in the epithelioid trophoblastic tumour component.
Mixed trophoblastic tumour (mixed placental site trophoblastic tumour and epithelioid trophoblastic tumour). Low-power view of the placental site trophoblastic tumour component (lower) and epithelioid trophoblastic tumour (upper).
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). Low-power view with choriocarcinoma in the lower-right corner gradually merging with epithelioid trophoblastic tumour in the upper left. Choriocarcinoma is present as sheets of pleomorphic tumour and epithelioid trophoblastic tumour is present in the form of nests with eosinophilic hyaline-like material.
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). Choriocarcinoma comprising a haemorrhagic solid destructive mass with biphasic proliferation of pleomorphic mononuclear intermediate/cytotrophoblastic cells rimmed by multinucleated syncytiotrophoblasts.
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). Epithelioid trophoblastic tumour showing a nodular growth pattern, with relatively uniform, medium-sized tumour cells; clear to eosinophilic cytoplasm; and bland-appearing nuclei. Eosinophilic hyalinized material simulating keratinizing squamous cell carcinoma is seen within these nests.
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). Nests of epithelioid trophoblastic tumour (left) are strongly positive with p63, whereas sheets of choriocarcinoma (right) show minimal nuclear staining.
Mixed trophoblastic tumour (mixed choriocarcinoma and epithelioid trophoblastic tumour). There is heavy cytoplasmic staining for hCG in the choriocarcinoma component (right), whereas very few cells show hCG expression in the epithelioid trophoblastic tumour component (left).

Q: When involving the endometrium, Extranodal Marginal Zone Lymphoma of Mucosa-Associated Lymphoid Tissue typically forms discrete to coalescent nodules of monotonous [...] and characteristically lacks conspicuous lymphoepithelial lesions.
Endometrial marginal zone lymphoma. Low-power image shows multiple crowded nodules of lymphoid cells in the endometrium and infiltrating myometrium.
Endometrial marginal zone lymphoma. Higher-power image shows monotonous small lymphoid cells with pale cytoplasm adjacent to an endometrial gland.
A: small lymphoid cells
Back Extra: Extranodal Marginal Zone Lymphoma of Mucosa-Associated Lymphoid Tissue
- Clinical: Extranodal Marginal Zone Lymphoma of Mucosa-Associated Lymphoid Tissue (MALT lymphoma) affects older women, with a median age of 66 years. It is typically an incidental finding.
- Micro: Endometrial MZL shows discrete to coalescent nodules with monotonous small lymphoid cells, lacking conspicuous lymphoepithelial lesions.
- Ancillary: Clonal rearrangement of IGH can usually be demonstrated, but FISH analysis for IGH and MALT1 rearrangements is typically negative.
Reference Gallery:
Endometrial marginal zone lymphoma. Low-power image shows multiple crowded nodules of lymphoid cells in the endometrium and infiltrating myometrium.
Endometrial marginal zone lymphoma. Higher-power image shows monotonous small lymphoid cells with pale cytoplasm adjacent to an endometrial gland.
Endometrial marginal zone lymphoma. Immunostaining for CD20 shows staining of a nodule of neoplastic cells.

Q: Immunohistochemical staining in Extranodal Marginal Zone Lymphoma of Mucosa-Associated Lymphoid Tissue will highlight the neoplastic nodules with pan-B-cell markers such as [...].
Endometrial marginal zone lymphoma. Immunostaining for CD20 shows staining of a nodule of neoplastic cells.
A: CD20
Back Extra: Extranodal Marginal Zone Lymphoma of Mucosa-Associated Lymphoid Tissue
- Clinical: Extranodal Marginal Zone Lymphoma of Mucosa-Associated Lymphoid Tissue (MALT lymphoma) affects older women, with a median age of 66 years. It is typically an incidental finding.
- Micro: Endometrial MZL shows discrete to coalescent nodules with monotonous small lymphoid cells, lacking conspicuous lymphoepithelial lesions.
- Ancillary: Clonal rearrangement of IGH can usually be demonstrated, but FISH analysis for IGH and MALT1 rearrangements is typically negative.
Reference Gallery:
Endometrial marginal zone lymphoma. Low-power image shows multiple crowded nodules of lymphoid cells in the endometrium and infiltrating myometrium.
Endometrial marginal zone lymphoma. Higher-power image shows monotonous small lymphoid cells with pale cytoplasm adjacent to an endometrial gland.
Endometrial marginal zone lymphoma. Immunostaining for CD20 shows staining of a nodule of neoplastic cells.

Q: Patients with Myeloid Sarcoma may present with an extramedullary tumor mass composed of immature monocytic cells, which occurs either concurrently or in patients with a history of [...].
Myeloid sarcoma. The uterine cervix is replaced by a tumour mass of myeloid cells. The patient initially presented with vaginal bleeding.
Myeloid sarcoma. High-power magnification showing many immature monocytic cells.
A: acute myeloid leukemia (AML)
Back Extra: Myeloid Sarcoma
- Clinical: Patients with myeloid sarcoma may present with vaginal bleeding, dysmenorrhoea, or a mass, and may have a history or simultaneous evidence of acute myeloid leukaemia (AML).
- Micro: Myeloid sarcoma diffusely replaces tissues with a single-file pattern, numerous mitoses, and cells with thin nuclear membranes, fine chromatin, and pinpoint nucleoli.
- Ancillary: Tumour cells are positive for CD68, myeloperoxidase, and other myeloid markers, and may share cytogenetic/molecular abnormalities with AML.
Reference Gallery:
Myeloid sarcoma. The uterine cervix is replaced by a tumour mass of myeloid cells. The patient initially presented with vaginal bleeding.
Myeloid sarcoma. High-power magnification showing many immature monocytic cells.
Myeloid sarcoma. Immunohistochemical analysis shows that the cells are strongly positive for CD68, supporting myeloid/monocytic lineage.

Q: Immunohistochemical analysis of Myeloid Sarcoma confirms myeloid/monocytic lineage through strong positivity for markers such as myeloperoxidase (MPO) and [...].
Myeloid sarcoma. Immunohistochemical analysis shows that the cells are strongly positive for CD68, supporting myeloid/monocytic lineage.
A: CD68
Back Extra: Myeloid Sarcoma
- Clinical: Patients with myeloid sarcoma may present with vaginal bleeding, dysmenorrhoea, or a mass, and may have a history or simultaneous evidence of acute myeloid leukaemia (AML).
- Micro: Myeloid sarcoma diffusely replaces tissues with a single-file pattern, numerous mitoses, and cells with thin nuclear membranes, fine chromatin, and pinpoint nucleoli.
- Ancillary: Tumour cells are positive for CD68, myeloperoxidase, and other myeloid markers, and may share cytogenetic/molecular abnormalities with AML.
Reference Gallery:
Myeloid sarcoma. The uterine cervix is replaced by a tumour mass of myeloid cells. The patient initially presented with vaginal bleeding.
Myeloid sarcoma. High-power magnification showing many immature monocytic cells.
Myeloid sarcoma. Immunohistochemical analysis shows that the cells are strongly positive for CD68, supporting myeloid/monocytic lineage.

Q: Histologically, an Endometrial Stromal Nodule is composed of uniform small cells with scant cytoplasm and is distinguished from its malignant counterpart by being completely well-[...] from the surrounding myometrium.
Endometrial stromal nodule. The tumour is well circumscribed from the surrounding myometrium. Small cells with scant cytoplasm and oval nuclei show a diffuse growth.
A: circumscribed
Back Extra: Endometrial Stromal Nodule
- Clinical: Patients may present with abnormal uterine bleeding, abdominal pain, enlarged uterus, or a pelvic mass.
- Micro: Tumours are circumscribed, densely cellular, and composed of uniform small cells with scant cytoplasm, round to oval nuclei, and inconspicuous nucleoli.
- Ancillary: Approximately 70% of tumours harbour t(7;17)(p21;q15) resulting in JAZF1-SUZ12 fusion.
Reference Gallery:
Endometrial stromal nodule. The tumour is well circumscribed from the surrounding myometrium. Small cells with scant cytoplasm and oval nuclei show a diffuse growth.

Q: In Placental Site Nodule and Plaque, the characteristic small (< 5 mm), circumscribed, paucicellular hyalinized nodules are predominantly composed of [...] with minimal cytological atypia.
Placental site nodule. Small (< 5 mm), circumscribed, paucicellular hyalinized nodules composed of intermediate trophoblast.
Placental site nodule. Paucicellular hyalinized nodules composed of intermediate trophoblast with minimal cytological atypia and no mitotic activity.
A: intermediate trophoblast
Back Extra: Placental Site Nodule and Plaque
- Clinical: Placental site nodule/plaque (PSN) and atypical placental site nodule (APSN) are generally incidental findings in women of childbearing age, often presenting with vaginal bleeding.
- Micro: PSN is characterized by small (< 5 mm), circumscribed, paucicellular hyalinized nodules of intermediate trophoblast, with minimal cytological atypia and no mitotic activity.
- Ancillary: Lesional cells in PSN show reactivity for cytokeratins, α-inhibin, GATA3, PLAP, and p63, but are usually negative for hPL and MCAM (CD146).
Reference Gallery:
Atypical placental site nodule. Cellular nodule with scant hyalinization and central necrosis.
Atypical placental site nodule. Edges are less well defined, with small clusters of loose cells (pseudopods) that mimic invasion.
Atypical placental site nodule. Cohesive nests and cords of chorion laeve–type intermediate trophoblast with cytological and nuclear atypia.
Atypical placental site nodule. Ki-67 proliferation index > 5% is seen.
Placental site nodule. Small (< 5 mm), circumscribed, paucicellular hyalinized nodules composed of intermediate trophoblast.
Placental site nodule. Higher power of small (< 5 mm), circumscribed, paucicellular hyalinized nodules composed of intermediate trophoblast.
Placental site nodule. Paucicellular hyalinized nodules composed of intermediate trophoblast with minimal cytological atypia and no mitotic activity.
Placental site nodule. There is a low Ki-67 proliferation index (< 5%).
Placental site nodule. Lesional cells are strongly positive for p63.

Q: Immunohistochemical staining of Placental Site Nodule and Plaque demonstrates characteristic strong nuclear positivity for [...], along with cytokeratins and α-inhibin.
Placental site nodule. Lesional cells are strongly positive for p63.
A: p63
Back Extra: Placental Site Nodule and Plaque
- Clinical: Placental site nodule/plaque (PSN) and atypical placental site nodule (APSN) are generally incidental findings in women of childbearing age, often presenting with vaginal bleeding.
- Micro: PSN is characterized by small (< 5 mm), circumscribed, paucicellular hyalinized nodules of intermediate trophoblast, with minimal cytological atypia and no mitotic activity.
- Ancillary: Lesional cells in PSN show reactivity for cytokeratins, α-inhibin, GATA3, PLAP, and p63, but are usually negative for hPL and MCAM (CD146).
Reference Gallery:
Atypical placental site nodule. Cellular nodule with scant hyalinization and central necrosis.
Atypical placental site nodule. Edges are less well defined, with small clusters of loose cells (pseudopods) that mimic invasion.
Atypical placental site nodule. Cohesive nests and cords of chorion laeve–type intermediate trophoblast with cytological and nuclear atypia.
Atypical placental site nodule. Ki-67 proliferation index > 5% is seen.
Placental site nodule. Small (< 5 mm), circumscribed, paucicellular hyalinized nodules composed of intermediate trophoblast.
Placental site nodule. Higher power of small (< 5 mm), circumscribed, paucicellular hyalinized nodules composed of intermediate trophoblast.
Placental site nodule. Paucicellular hyalinized nodules composed of intermediate trophoblast with minimal cytological atypia and no mitotic activity.
Placental site nodule. There is a low Ki-67 proliferation index (< 5%).
Placental site nodule. Lesional cells are strongly positive for p63.

Q: To help differentiate from atypical variants, a typical Placental Site Nodule and Plaque classically demonstrates a Ki-67 proliferation index of [...].
Placental site nodule. There is a low Ki-67 proliferation index (< 5%).
A: < 5%
Back Extra: Placental Site Nodule and Plaque
- Clinical: Placental site nodule/plaque (PSN) and atypical placental site nodule (APSN) are generally incidental findings in women of childbearing age, often presenting with vaginal bleeding.
- Micro: PSN is characterized by small (< 5 mm), circumscribed, paucicellular hyalinized nodules of intermediate trophoblast, with minimal cytological atypia and no mitotic activity.
- Ancillary: Lesional cells in PSN show reactivity for cytokeratins, α-inhibin, GATA3, PLAP, and p63, but are usually negative for hPL and MCAM (CD146).
Reference Gallery:
Atypical placental site nodule. Cellular nodule with scant hyalinization and central necrosis.
Atypical placental site nodule. Edges are less well defined, with small clusters of loose cells (pseudopods) that mimic invasion.
Atypical placental site nodule. Cohesive nests and cords of chorion laeve–type intermediate trophoblast with cytological and nuclear atypia.
Atypical placental site nodule. Ki-67 proliferation index > 5% is seen.
Placental site nodule. Small (< 5 mm), circumscribed, paucicellular hyalinized nodules composed of intermediate trophoblast.
Placental site nodule. Higher power of small (< 5 mm), circumscribed, paucicellular hyalinized nodules composed of intermediate trophoblast.
Placental site nodule. Paucicellular hyalinized nodules composed of intermediate trophoblast with minimal cytological atypia and no mitotic activity.
Placental site nodule. There is a low Ki-67 proliferation index (< 5%).
Placental site nodule. Lesional cells are strongly positive for p63.

Q: Histologically, [...] is characterized by the extensive intravascular growth of bland smooth muscle forming worm-like plugs within veins, often accompanied by thick-walled vasculature, hyalinization, and hydropic change.
Intravenous leiomyomatosis. Intravascular growth of bland smooth muscle with hyalinization and thick-walled vasculature.
Intravenous leiomyomatosis. Extensive intravascular growth of focally cellular smooth muscle is noted, forming worm-like plugs within veins. There is focal hydropic change as well as a component of endometrial glands (intravascular adenomyomatosis).
A: Intravenous Leiomyomatosis
Back Extra: Intravenous Leiomyomatosis
- Clinical: Patients often present with symptoms similar to those of leiomyomas, but may also have chest pain, dyspnoea, syncope, or pulmonary embolism due to right heart or pulmonary artery involvement.
- Micro: Intravascular growth of benign smooth muscle cells, resembling typical leiomyoma or its subtypes, with frequent hydropic change, hyalinization, and thick-walled vessels.
- Ancillary: t(12;14), involving HMGA2, and HMGA2 protein overexpression have been identified in a subset of cases, suggesting a pathogenetic relationship with uterine leiomyomas.
Reference Gallery:
Intravenous leiomyomatosis. The myometrium shows multiple white to tan nodules.
Intravenous leiomyomatosis. Intravascular growth of bland smooth muscle with hyalinization and thick-walled vasculature.
Intravenous leiomyomatosis. Extensive intravascular growth of focally cellular smooth muscle is noted, forming worm-like plugs within veins. There is focal hydropic change as well as a component of endometrial glands (intravascular adenomyomatosis).

Q: Grossly, Intravenous Leiomyomatosis presents with multiple white to tan nodules in the myometrium, and clinically it may uniquely cause syncope, dyspnea, or pulmonary embolism due to extensive intravascular extension into the [...].
Intravenous leiomyomatosis. The myometrium shows multiple white to tan nodules.
A: right heart
Back Extra: Intravenous Leiomyomatosis
- Clinical: Patients often present with symptoms similar to those of leiomyomas, but may also have chest pain, dyspnoea, syncope, or pulmonary embolism due to right heart or pulmonary artery involvement.
- Micro: Intravascular growth of benign smooth muscle cells, resembling typical leiomyoma or its subtypes, with frequent hydropic change, hyalinization, and thick-walled vessels.
- Ancillary: t(12;14), involving HMGA2, and HMGA2 protein overexpression have been identified in a subset of cases, suggesting a pathogenetic relationship with uterine leiomyomas.
Reference Gallery:
Intravenous leiomyomatosis. The myometrium shows multiple white to tan nodules.
Intravenous leiomyomatosis. Intravascular growth of bland smooth muscle with hyalinization and thick-walled vasculature.
Intravenous leiomyomatosis. Extensive intravascular growth of focally cellular smooth muscle is noted, forming worm-like plugs within veins. There is focal hydropic change as well as a component of endometrial glands (intravascular adenomyomatosis).

Q: In Hereditary Leiomyomatosis and Renal Cell Carcinoma, uterine leiomyomas characteristically feature prominent [...] surrounded by perinucleolar halos, often accompanied by alveolar pattern edema.
Leiomyoma. Uterine leiomyoma from a patient with hereditary leiomyomatosis and renal cell carcinoma. Conspicuous eosinophilic nucleoli are found.
Leiomyoma. Uterine leiomyoma from a patient with hereditary leiomyomatosis and renal cell carcinoma. Conspicuous eosinophilic nucleoli are found.
A: eosinophilic nucleoli
Back Extra: Hereditary Leiomyomatosis and Renal Cell Carcinoma
- Clinical: Hereditary Leiomyomatosis and Renal Cell Carcinoma (HLRCC) is characterized by early-onset development of cutaneous and uterine leiomyomas, and renal cell carcinoma (most frequently type 2 papillary RCC).
- Micro: Uterine leiomyomas in HLRCC show a staghorn vascular pattern, alveolar pattern oedema, and prominent eosinophilic nucleoli surrounded by perinucleolar haloes.
- Ancillary: Genetic testing for germline mutations in the FH (fumarase) gene is essential for the definitive diagnosis of HLRCC. Immunohistochemistry often shows loss of fumarate hydratase staining in the tumour cells.
Reference Gallery:
Leiomyoma. Uterine leiomyoma from a patient with hereditary leiomyomatosis and renal cell carcinoma. Conspicuous eosinophilic nucleoli are found.
Leiomyoma. Uterine leiomyoma from a patient with hereditary leiomyomatosis and renal cell carcinoma. Conspicuous eosinophilic nucleoli are found.
Leiomyoma. Fumarate hydratase–deficient leiomyoma. Immunohistochemically, the smooth muscle cells are negative for fumarate hydratase (fumarase). Note that the vessels serve as an internal positive control (DAB staining).

Q: The diagnosis of Hereditary Leiomyomatosis and Renal Cell Carcinoma is supported by immunohistochemistry demonstrating loss of [...] staining in the tumor cells.
Leiomyoma. Fumarate hydratase–deficient leiomyoma. Immunohistochemically, the smooth muscle cells are negative for fumarate hydratase (fumarase). Note that the vessels serve as an internal positive control (DAB staining).
A: fumarate hydratase
Back Extra: Hereditary Leiomyomatosis and Renal Cell Carcinoma
- Clinical: Hereditary Leiomyomatosis and Renal Cell Carcinoma (HLRCC) is characterized by early-onset development of cutaneous and uterine leiomyomas, and renal cell carcinoma (most frequently type 2 papillary RCC).
- Micro: Uterine leiomyomas in HLRCC show a staghorn vascular pattern, alveolar pattern oedema, and prominent eosinophilic nucleoli surrounded by perinucleolar haloes.
- Ancillary: Genetic testing for germline mutations in the FH (fumarase) gene is essential for the definitive diagnosis of HLRCC. Immunohistochemistry often shows loss of fumarate hydratase staining in the tumour cells.
Reference Gallery:
Leiomyoma. Uterine leiomyoma from a patient with hereditary leiomyomatosis and renal cell carcinoma. Conspicuous eosinophilic nucleoli are found.
Leiomyoma. Uterine leiomyoma from a patient with hereditary leiomyomatosis and renal cell carcinoma. Conspicuous eosinophilic nucleoli are found.
Leiomyoma. Fumarate hydratase–deficient leiomyoma. Immunohistochemically, the smooth muscle cells are negative for fumarate hydratase (fumarase). Note that the vessels serve as an internal positive control (DAB staining).

Q: Grossly presenting as a well-circumscribed, firm tumor that stretches the overlying fallopian tube with prominent edema, [...] can rarely be clinically associated with pseudo-Meigs syndrome.
Leiomyoma. The tumour is well circumscribed, with a white firm cut surface present only at the periphery because most of the tumour is associated with prominent oedema. The tumour arises in the broad ligament and stretches the overlying fallopian tube (top).
A: Leiomyoma of the Broad Ligament and Other Uterine Ligaments
Back Extra: Leiomyoma of the Broad Ligament and Other Uterine Ligaments
- Clinical: Leiomyomas of the broad ligament and other uterine ligaments often present similarly to uterine leiomyomas and may coexist with them. Massive ovarian oedema and pseudo-Meigs syndrome have been described.
- Micro: The histological changes in these leiomyomas are similar to those seen in uterine leiomyomas, including bizarre nuclei, epithelioid morphology, and lipomatous differentiation.
- Ancillary: Ancillary studies are generally not clinically relevant for the diagnosis of leiomyomas of the broad ligament and other uterine ligaments.
Reference Gallery:
Leiomyoma. The tumour is well circumscribed, with a white firm cut surface present only at the periphery because most of the tumour is associated with prominent oedema. The tumour arises in the broad ligament and stretches the overlying fallopian tube (top).
Leiomyoma. The tumour shows smooth muscle cells with focal bizarre nuclei and focal oedema juxtaposed to benign cartilaginous differentiation (lower left).
Leiomyoma. The tumour shows a typical appearance in the upper-left corner of this view and extensive hydropic change in the lower-right area.

Q: Histologically, [...] consists of typical smooth muscle cells that frequently undergo secondary alterations, such as focal bizarre nuclei, extensive hydropic change, and juxtaposed benign cartilaginous differentiation.
Leiomyoma. The tumour shows smooth muscle cells with focal bizarre nuclei and focal oedema juxtaposed to benign cartilaginous differentiation (lower left).
Leiomyoma. The tumour shows a typical appearance in the upper-left corner of this view and extensive hydropic change in the lower-right area.
A: Leiomyoma of the Broad Ligament and Other Uterine Ligaments
Back Extra: Leiomyoma of the Broad Ligament and Other Uterine Ligaments
- Clinical: Leiomyomas of the broad ligament and other uterine ligaments often present similarly to uterine leiomyomas and may coexist with them. Massive ovarian oedema and pseudo-Meigs syndrome have been described.
- Micro: The histological changes in these leiomyomas are similar to those seen in uterine leiomyomas, including bizarre nuclei, epithelioid morphology, and lipomatous differentiation.
- Ancillary: Ancillary studies are generally not clinically relevant for the diagnosis of leiomyomas of the broad ligament and other uterine ligaments.
Reference Gallery:
Leiomyoma. The tumour is well circumscribed, with a white firm cut surface present only at the periphery because most of the tumour is associated with prominent oedema. The tumour arises in the broad ligament and stretches the overlying fallopian tube (top).
Leiomyoma. The tumour shows smooth muscle cells with focal bizarre nuclei and focal oedema juxtaposed to benign cartilaginous differentiation (lower left).
Leiomyoma. The tumour shows a typical appearance in the upper-left corner of this view and extensive hydropic change in the lower-right area.

Q: Microscopically, lesions of Metastasizing Leiomyoma feature a well-demarcated, cytologically bland proliferation of intersecting fascicles of [...] cells that typically entrap alveoli.
Benign metastasizing leiomyoma. Histologically bland-appearing spindle smooth muscle proliferation entrapping alveoli.
A: spindle smooth muscle
Back Extra: Metastasizing Leiomyoma
- Clinical: Lesions are often incidentally discovered on radiological studies, but patients may present with respiratory symptoms (e.g., dyspnoea, cough).
- Micro: Histologically, the lesion shows a well-demarcated proliferation of intersecting fascicles of spindle cells with cytologically bland features and minimal to absent mitoses.
- Ancillary: Molecular analysis reveals broad similarities with the mutations and expression abnormalities found in leiomyoma, including MED12 mutations.
Reference Gallery:
Benign metastasizing leiomyoma. Histologically bland-appearing spindle smooth muscle proliferation entrapping alveoli.
Benign metastasizing leiomyoma. Leiomyoma presenting with metastases to the lung.

Q: In Metastasizing Leiomyoma, patients often present with incidental radiological findings or respiratory symptoms (e.g., dyspnea, cough) due to cytologically benign metastatic deposits most commonly found in the [...].
Benign metastasizing leiomyoma. Leiomyoma presenting with metastases to the lung.
A: lung
Back Extra: Metastasizing Leiomyoma
- Clinical: Lesions are often incidentally discovered on radiological studies, but patients may present with respiratory symptoms (e.g., dyspnoea, cough).
- Micro: Histologically, the lesion shows a well-demarcated proliferation of intersecting fascicles of spindle cells with cytologically bland features and minimal to absent mitoses.
- Ancillary: Molecular analysis reveals broad similarities with the mutations and expression abnormalities found in leiomyoma, including MED12 mutations.
Reference Gallery:
Benign metastasizing leiomyoma. Histologically bland-appearing spindle smooth muscle proliferation entrapping alveoli.
Benign metastasizing leiomyoma. Leiomyoma presenting with metastases to the lung.

Q: Grossly, a Uterine Leiomyoma typically presents as a well-circumscribed, firm mass with a classic [...] white cut surface, which microscopically corresponds to bland spindle cells arranged in intersecting fascicles.
Typical uterine leiomyomas. Tumours are well circumscribed, with a firm, whorled, and white cut surface. They are often intramyometrial but can be subserosal and pedunculated and may secondarily torse, becoming a so-called parasitic leiomyoma.
Uterine leiomyoma (spindle cell). The spindle cells have bland cytological features, with elongated nuclei and fine nuclear chromatin.
A: whorled
Back Extra: Uterine Leiomyoma
- Clinical: Uterine leiomyomas are often asymptomatic but can present with menorrhagia, pelvic pain, and symptoms related to size, location, and number of tumours. They are most prevalent in African-American women.
- Micro: Most leiomyomas are well-demarcated with spindle cells arranged in intersecting fascicles. Prominent hyalinization can give a pseudoepithelioid appearance. Infarct-type necrosis may occur.
- Ancillary: Leiomyomas express desmin, h-caldesmon, SMA, MSA, calponin, and SMMHC. CD10 is often positive in cellular leiomyomas, and loss of fumarate hydratase staining may indicate underlying FH mutations.
Reference Gallery:
Uterine leiomyoma (spindle cell). The spindle cells have bland cytological features, with elongated nuclei and fine nuclear chromatin.
Lipoleiomyoma. Mature adipocytes are intermingled between the spindle smooth muscle cells.
Uterine leiomyoma. Stromal hyalinization results in compartmentalization and cording of tumour cells, imparting a pseudoepithelioid appearance.
Epithelioid leiomyoma. The tumour cells are polygonal, with eosinophilic or clear cytoplasm and lack of cytological atypia.
Myxoid leiomyoma. Cytologically benign spindle cells are widely separated by myxoid stroma.
Dissecting leiomyoma. Nodules of tumour with hydropic change infiltrate the myometrium.
Fumarate hydratase–deficient leiomyoma. Cellular tumour with scattered bizarre cells and staghorn blood vessels.
Fumarate hydratase–deficient leiomyoma. Tumour cells have oval nuclei and are arranged in chains. Eosinophilic nucleoli with perinucleolar haloes are prominent.
Typical uterine leiomyomas. Tumours are well circumscribed, with a firm, whorled, and white cut surface. They are often intramyometrial but can be subserosal and pedunculated and may secondarily torse, becoming a so-called parasitic leiomyoma.
Leiomyoma with bizarre nuclei. The cells with bizarre nuclei have a diffuse distribution within the tumour; they display smudged nuclear chromatin and some nuclear pseudoinclusions. Karyorrhectic nuclei (often mistaken for atypical mitoses) are seen.
Infarct-type necrosis in uterine leiomyoma. An area of central haemorrhage is surrounded by hyalinized tissue adjacent to a hypercellular band of smooth muscle.
Leiomyoma with bizarre nuclei. Mononucleated and multinucleated bizarre cells show eosinophilic or globular (rhabdoid) cytoplasm and multiple pseudoinclusions.

Q: A notable morphologic variant of Uterine Leiomyoma features prominent eosinophilic nucleoli with perinucleolar halos and scattered staghorn blood vessels, which is highly suggestive of [...] deficiency.
Fumarate hydratase–deficient leiomyoma. Cellular tumour with scattered bizarre cells and staghorn blood vessels.
Fumarate hydratase–deficient leiomyoma. Tumour cells have oval nuclei and are arranged in chains. Eosinophilic nucleoli with perinucleolar haloes are prominent.
A: fumarate hydratase
Back Extra: Uterine Leiomyoma
- Clinical: Uterine leiomyomas are often asymptomatic but can present with menorrhagia, pelvic pain, and symptoms related to size, location, and number of tumours. They are most prevalent in African-American women.
- Micro: Most leiomyomas are well-demarcated with spindle cells arranged in intersecting fascicles. Prominent hyalinization can give a pseudoepithelioid appearance. Infarct-type necrosis may occur.
- Ancillary: Leiomyomas express desmin, h-caldesmon, SMA, MSA, calponin, and SMMHC. CD10 is often positive in cellular leiomyomas, and loss of fumarate hydratase staining may indicate underlying FH mutations.
Reference Gallery:
Uterine leiomyoma (spindle cell). The spindle cells have bland cytological features, with elongated nuclei and fine nuclear chromatin.
Lipoleiomyoma. Mature adipocytes are intermingled between the spindle smooth muscle cells.
Uterine leiomyoma. Stromal hyalinization results in compartmentalization and cording of tumour cells, imparting a pseudoepithelioid appearance.
Epithelioid leiomyoma. The tumour cells are polygonal, with eosinophilic or clear cytoplasm and lack of cytological atypia.
Myxoid leiomyoma. Cytologically benign spindle cells are widely separated by myxoid stroma.
Dissecting leiomyoma. Nodules of tumour with hydropic change infiltrate the myometrium.
Fumarate hydratase–deficient leiomyoma. Cellular tumour with scattered bizarre cells and staghorn blood vessels.
Fumarate hydratase–deficient leiomyoma. Tumour cells have oval nuclei and are arranged in chains. Eosinophilic nucleoli with perinucleolar haloes are prominent.
Typical uterine leiomyomas. Tumours are well circumscribed, with a firm, whorled, and white cut surface. They are often intramyometrial but can be subserosal and pedunculated and may secondarily torse, becoming a so-called parasitic leiomyoma.
Leiomyoma with bizarre nuclei. The cells with bizarre nuclei have a diffuse distribution within the tumour; they display smudged nuclear chromatin and some nuclear pseudoinclusions. Karyorrhectic nuclei (often mistaken for atypical mitoses) are seen.
Infarct-type necrosis in uterine leiomyoma. An area of central haemorrhage is surrounded by hyalinized tissue adjacent to a hypercellular band of smooth muscle.
Leiomyoma with bizarre nuclei. Mononucleated and multinucleated bizarre cells show eosinophilic or globular (rhabdoid) cytoplasm and multiple pseudoinclusions.

Q: A specific variant of Uterine Leiomyoma can mimic malignancy by displaying smudged chromatin, prominent nuclear pseudoinclusions, and karyorrhectic nuclei, and is classified as a leiomyoma with [...].
Leiomyoma with bizarre nuclei. The cells with bizarre nuclei have a diffuse distribution within the tumour; they display smudged nuclear chromatin and some nuclear pseudoinclusions. Karyorrhectic nuclei (often mistaken for atypical mitoses) are seen.
Leiomyoma with bizarre nuclei. Mononucleated and multinucleated bizarre cells show eosinophilic or globular (rhabdoid) cytoplasm and multiple pseudoinclusions.
A: bizarre nuclei
Back Extra: Uterine Leiomyoma
- Clinical: Uterine leiomyomas are often asymptomatic but can present with menorrhagia, pelvic pain, and symptoms related to size, location, and number of tumours. They are most prevalent in African-American women.
- Micro: Most leiomyomas are well-demarcated with spindle cells arranged in intersecting fascicles. Prominent hyalinization can give a pseudoepithelioid appearance. Infarct-type necrosis may occur.
- Ancillary: Leiomyomas express desmin, h-caldesmon, SMA, MSA, calponin, and SMMHC. CD10 is often positive in cellular leiomyomas, and loss of fumarate hydratase staining may indicate underlying FH mutations.
Reference Gallery:
Uterine leiomyoma (spindle cell). The spindle cells have bland cytological features, with elongated nuclei and fine nuclear chromatin.
Lipoleiomyoma. Mature adipocytes are intermingled between the spindle smooth muscle cells.
Uterine leiomyoma. Stromal hyalinization results in compartmentalization and cording of tumour cells, imparting a pseudoepithelioid appearance.
Epithelioid leiomyoma. The tumour cells are polygonal, with eosinophilic or clear cytoplasm and lack of cytological atypia.
Myxoid leiomyoma. Cytologically benign spindle cells are widely separated by myxoid stroma.
Dissecting leiomyoma. Nodules of tumour with hydropic change infiltrate the myometrium.
Fumarate hydratase–deficient leiomyoma. Cellular tumour with scattered bizarre cells and staghorn blood vessels.
Fumarate hydratase–deficient leiomyoma. Tumour cells have oval nuclei and are arranged in chains. Eosinophilic nucleoli with perinucleolar haloes are prominent.
Typical uterine leiomyomas. Tumours are well circumscribed, with a firm, whorled, and white cut surface. They are often intramyometrial but can be subserosal and pedunculated and may secondarily torse, becoming a so-called parasitic leiomyoma.
Leiomyoma with bizarre nuclei. The cells with bizarre nuclei have a diffuse distribution within the tumour; they display smudged nuclear chromatin and some nuclear pseudoinclusions. Karyorrhectic nuclei (often mistaken for atypical mitoses) are seen.
Infarct-type necrosis in uterine leiomyoma. An area of central haemorrhage is surrounded by hyalinized tissue adjacent to a hypercellular band of smooth muscle.
Leiomyoma with bizarre nuclei. Mononucleated and multinucleated bizarre cells show eosinophilic or globular (rhabdoid) cytoplasm and multiple pseudoinclusions.

Q: Histologically, a [...] is characterized by nests, sheets, or fascicles of epithelioid and/or spindled cells with clear to eosinophilic granular cytoplasm, which are typically surrounded by a delicate vasculature.
Perivascular epithelioid cell tumour (PEComa). Conventional PEComa composed of epithelioid cells, with clear to eosinophilic granular cytoplasm, that form small nests surrounded by delicate vasculature.
Perivascular epithelioid cell tumour (PEComa). Conventional PEComa composed predominantly of spindled cells, with pale eosinophilic granular cytoplasm, that form short fascicles.
A: perivascular epithelioid cell tumor (PEComa)
Back Extra: Perivascular Epithelioid Cell Tumour (PEComa)
- Clinical: Patients typically present with a pelvic mass, abnormal bleeding, or abdominopelvic pain; patient age ranges from 16 to 77 years (mean: 51 years).
- Micro: Conventional PEComas are composed of epithelioid and/or spindled cells with clear to eosinophilic granular cytoplasm, arranged in nests, sheets, or fascicles, often surrounded by delicate vasculature.
- Ancillary: Conventional PEComas express HMB45, melan-A, and smooth muscle markers (SMA, desmin, and h-caldesmon) with variable intensity. TFE3 translocation–associated PEComas are diffusely positive for TFE3, HMB45, and cathepsin K.
Reference Gallery:
Perivascular epithelioid cell tumour (PEComa). Conventional PEComa composed of epithelioid cells, with clear to eosinophilic granular cytoplasm, that form small nests surrounded by delicate vasculature.
Perivascular epithelioid cell tumour (PEComa). Conventional PEComa composed predominantly of spindled cells, with pale eosinophilic granular cytoplasm, that form short fascicles.
Perivascular epithelioid cell tumour (PEComa). TFE3 translocation–associated PEComa composed of epithelioid cells with clear or clear to eosinophilic granular cytoplasm with a sheet-like growth. Melanin pigment is seen.

Q: In a perivascular epithelioid cell tumor (PEComa), a specific subset demonstrates a sheet-like growth pattern of epithelioid cells and may contain visible melanin pigment (as seen in the image); this morphological variant is characteristically associated with a [...].
Perivascular epithelioid cell tumour (PEComa). TFE3 translocation–associated PEComa composed of epithelioid cells with clear or clear to eosinophilic granular cytoplasm with a sheet-like growth. Melanin pigment is seen.
A: TFE3 translocation
Back Extra: Perivascular Epithelioid Cell Tumour (PEComa)
- Clinical: Patients typically present with a pelvic mass, abnormal bleeding, or abdominopelvic pain; patient age ranges from 16 to 77 years (mean: 51 years).
- Micro: Conventional PEComas are composed of epithelioid and/or spindled cells with clear to eosinophilic granular cytoplasm, arranged in nests, sheets, or fascicles, often surrounded by delicate vasculature.
- Ancillary: Conventional PEComas express HMB45, melan-A, and smooth muscle markers (SMA, desmin, and h-caldesmon) with variable intensity. TFE3 translocation–associated PEComas are diffusely positive for TFE3, HMB45, and cathepsin K.
Reference Gallery:
Perivascular epithelioid cell tumour (PEComa). Conventional PEComa composed of epithelioid cells, with clear to eosinophilic granular cytoplasm, that form small nests surrounded by delicate vasculature.
Perivascular epithelioid cell tumour (PEComa). Conventional PEComa composed predominantly of spindled cells, with pale eosinophilic granular cytoplasm, that form short fascicles.
Perivascular epithelioid cell tumour (PEComa). TFE3 translocation–associated PEComa composed of epithelioid cells with clear or clear to eosinophilic granular cytoplasm with a sheet-like growth. Melanin pigment is seen.

Q: Histologically, an inflammatory myofibroblastic tumor typically displays spindled cells arranged in myxoid or fascicular patterns, admixed with a characteristic [...] inflammatory infiltrate.
Inflammatory myofibroblastic tumour. Bland spindled and ovoid cells are embedded in a myxoid matrix, imparting a tissue culture–like appearance. Notice the presence of a lymphoplasmacytic infiltrate throughout the tumour.
Inflammatory myofibroblastic tumour. Fascicular areas are commonly more cellular and have less inflammation than myxoid areas, closely resembling a smooth muscle neoplasm.
A: lymphoplasmacytic
Back Extra: Inflammatory Myofibroblastic Tumour
- Clinical: Inflammatory Myofibroblastic Tumours (IMTs) may cause abnormal uterine bleeding or be discovered incidentally during hysterectomy or caesarean section. They typically affect adult, premenopausal women (median age: 38 years).
- Micro: IMTs show a mixed histological pattern, including loose myxoid, fascicular/compact, and hyalinized areas. Cells are spindled with eosinophilic cytoplasm and elongated nuclei, and there is a lymphoplasmacytic inflammatory infiltrate.
- Ancillary: ALK positivity by immunohistochemistry is highly specific for IMT. ALK rearrangements (2p23.2-p23.1) are detected by FISH in about 75% of cases.
Reference Gallery:
Inflammatory myofibroblastic tumour. Bland spindled and ovoid cells are embedded in a myxoid matrix, imparting a tissue culture–like appearance. Notice the presence of a lymphoplasmacytic infiltrate throughout the tumour.
Inflammatory myofibroblastic tumour. Fascicular areas are commonly more cellular and have less inflammation than myxoid areas, closely resembling a smooth muscle neoplasm.
Inflammatory myofibroblastic tumour. Strong cytoplasmic ALK positivity.

Q: The diagnosis of an inflammatory myofibroblastic tumor is strongly supported by immunohistochemistry demonstrating cytoplasmic positivity for [...], which reflects a characteristic gene rearrangement at 2p23.
Inflammatory myofibroblastic tumour. Strong cytoplasmic ALK positivity.
A: ALK
Back Extra: Inflammatory Myofibroblastic Tumour
- Clinical: Inflammatory Myofibroblastic Tumours (IMTs) may cause abnormal uterine bleeding or be discovered incidentally during hysterectomy or caesarean section. They typically affect adult, premenopausal women (median age: 38 years).
- Micro: IMTs show a mixed histological pattern, including loose myxoid, fascicular/compact, and hyalinized areas. Cells are spindled with eosinophilic cytoplasm and elongated nuclei, and there is a lymphoplasmacytic inflammatory infiltrate.
- Ancillary: ALK positivity by immunohistochemistry is highly specific for IMT. ALK rearrangements (2p23.2-p23.1) are detected by FISH in about 75% of cases.
Reference Gallery:
Inflammatory myofibroblastic tumour. Bland spindled and ovoid cells are embedded in a myxoid matrix, imparting a tissue culture–like appearance. Notice the presence of a lymphoplasmacytic infiltrate throughout the tumour.
Inflammatory myofibroblastic tumour. Fascicular areas are commonly more cellular and have less inflammation than myxoid areas, closely resembling a smooth muscle neoplasm.
Inflammatory myofibroblastic tumour. Strong cytoplasmic ALK positivity.

Q: By definition, a smooth muscle tumor of uncertain malignant potential lacks true tumor cell necrosis, but as seen on histology, it may exhibit [...].
Uterine smooth muscle tumour of uncertain malignant potential. The tumour shows necrosis of an uncertain nature.
A: necrosis of an uncertain nature
Back Extra: Smooth Muscle Tumour of Uncertain Malignant Potential
- Clinical: Smooth Muscle Tumour of Uncertain Malignant Potential (STUMP) typically occurs in reproductive-aged or postmenopausal patients, with a mean age of 43 years.
- Micro: STUMPs show features such as focal/multifocal or diffuse nuclear atypia, 2–4 mitoses/mm2, and lacking tumour cell necrosis.
- Ancillary: MED12 mutations occur in as many as 10% of these smooth muscle tumours, and PHH3 immunohistochemistry may be helpful to evaluate mitoses.
Reference Gallery:
Uterine smooth muscle tumour of uncertain malignant potential. The tumour shows necrosis of an uncertain nature.
Epithelioid smooth muscle tumour of uncertain malignant potential. The tumour has a multinodular growth at its periphery and it recurred.
Epithelioid smooth muscle tumour of uncertain malignant potential. The tumour has an irregular border with the surrounding myometrium. The tumour recurred in the peritoneum as multiple nodules.

Q: The [...] variant of a smooth muscle tumor of uncertain malignant potential can exhibit an irregular myometrial border or a multinodular growth pattern at its periphery, and carries a risk of peritoneal recurrence.
Epithelioid smooth muscle tumour of uncertain malignant potential. The tumour has a multinodular growth at its periphery and it recurred.
Epithelioid smooth muscle tumour of uncertain malignant potential. The tumour has an irregular border with the surrounding myometrium. The tumour recurred in the peritoneum as multiple nodules.
A: epithelioid
Back Extra: Smooth Muscle Tumour of Uncertain Malignant Potential
- Clinical: Smooth Muscle Tumour of Uncertain Malignant Potential (STUMP) typically occurs in reproductive-aged or postmenopausal patients, with a mean age of 43 years.
- Micro: STUMPs show features such as focal/multifocal or diffuse nuclear atypia, 2–4 mitoses/mm2, and lacking tumour cell necrosis.
- Ancillary: MED12 mutations occur in as many as 10% of these smooth muscle tumours, and PHH3 immunohistochemistry may be helpful to evaluate mitoses.
Reference Gallery:
Uterine smooth muscle tumour of uncertain malignant potential. The tumour shows necrosis of an uncertain nature.
Epithelioid smooth muscle tumour of uncertain malignant potential. The tumour has a multinodular growth at its periphery and it recurred.
Epithelioid smooth muscle tumour of uncertain malignant potential. The tumour has an irregular border with the surrounding myometrium. The tumour recurred in the peritoneum as multiple nodules.

Q: The provided image demonstrates nests of dyscohesive cells with ample granular eosinophilic cytoplasm and prominent nucleoli arranged in a distinct alveolar pattern, which is characteristic of [...].
Alveolar soft part sarcoma. An alveolar arrangement of dyscohesive cells with ample eosinophilic and somewhat granular cytoplasm, central to eccentrically located round nuclei and prominent nucleoli, is characteristic.
A: Alveolar Soft Part Sarcoma
Back Extra: Alveolar Soft Part Sarcoma
- Clinical: Patients with Alveolar Soft Part Sarcoma (ASPS) of the uterus, vagina, or vulva typically present with nonspecific signs and symptoms related to a mass, and most cases occur in patients in their second to fourth decade of life.
- Micro: ASPS shows a characteristic alveolar architecture with nests of dyscohesive cells having ample granular eosinophilic cytoplasm and prominent nucleoli.
- Ancillary: Immunohistochemically, TFE3 is diffusely and strongly positive, and the presence of TFE3 rearrangement or ASPSCR1-TFE3 fusion transcripts is diagnostically helpful.
Reference Gallery:
Alveolar soft part sarcoma. An alveolar arrangement of dyscohesive cells with ample eosinophilic and somewhat granular cytoplasm, central to eccentrically located round nuclei and prominent nucleoli, is characteristic.

Q: In Alveolar Soft Part Sarcoma, tumor cells typically possess ample, granular, eosinophilic cytoplasm and are arranged in a characteristic [...] architecture with central dyscohesion.
Alveolar soft part sarcoma. An alveolar arrangement of dyscohesive cells with ample eosinophilic and somewhat granular cytoplasm, central to eccentrically located round nuclei and prominent nucleoli, is characteristic.
A: alveolar
Back Extra: Alveolar Soft Part Sarcoma
- Clinical: Patients with Alveolar Soft Part Sarcoma (ASPS) of the uterus, vagina, or vulva typically present with nonspecific signs and symptoms related to a mass, and most cases occur in patients in their second to fourth decade of life.
- Micro: ASPS shows a characteristic alveolar architecture with nests of dyscohesive cells having ample granular eosinophilic cytoplasm and prominent nucleoli.
- Ancillary: Immunohistochemically, TFE3 is diffusely and strongly positive, and the presence of TFE3 rearrangement or ASPSCR1-TFE3 fusion transcripts is diagnostically helpful.
Reference Gallery:
Alveolar soft part sarcoma. An alveolar arrangement of dyscohesive cells with ample eosinophilic and somewhat granular cytoplasm, central to eccentrically located round nuclei and prominent nucleoli, is characteristic.

Q: In High-grade endometrial stromal sarcoma, particularly the YWHAE-NUTM2A/B fusion subtype, the formation of [...] can mimic a primitive neuroectodermal tumor (PNET), though diffuse positivity for cyclin D1 and BCOR aids in the distinction.
YWHAE-NUTM2A/B fusion–positive high-grade endometrial stromal sarcoma. Pseudorosette formation may be seen in these tumours and may cause confusion with primitive neuroectodermal tumour, confounded by the positivity of both primitive neuroectodermal tumour and high-grade endometrial stromal sarcoma for CD99. However, high-grade endometrial stromal sarcoma stains diffusely for cyclin D1 and BCOR (in contrast to primitive neuroectodermal tumour), allowing the distinction.
A: pseudorosettes
Back Extra: High-grade endometrial stromal sarcoma
- Clinical: High-grade endometrial stromal sarcoma commonly presents with abnormal uterine bleeding, pelvic pain, or a uterine mass. Patients with BCOR ITD high-grade endometrial stromal sarcomas tend to be younger.
- Micro: Tumours may show expansile, permeative, or infiltrative growth with brisk mitotic activity and necrosis. Pseudorosette formation can be seen, which is a key feature for distinguishing it from other tumours.
- Ancillary: Essential features include monomorphic high-grade round and/or spindle cells, brisk mitotic activity, and cyclin D1 and BCOR positivity in YWHAE-NUTM2A/B or ZC3H7B-BCOR fusion cases.
Reference Gallery:
YWHAE-NUTM2A/B fusion–positive high-grade endometrial stromal sarcoma. There is diffuse growth of small round tumour cells associated with delicate vasculature.
YWHAE-NUTM2A/B fusion–positive high-grade endometrial stromal sarcoma. The tumour cells are small, with scant eosinophilic cytoplasm and round to angulated nuclei displaying granular to vesicular chromatin.
YWHAE-NUTM2A/B fusion–positive high-grade endometrial stromal sarcoma. Pseudorosette formation may be seen in these tumours and may cause confusion with primitive neuroectodermal tumour, confounded by the positivity of both primitive neuroectodermal tumour and high-grade endometrial stromal sarcoma for CD99. However, high-grade endometrial stromal sarcoma stains diffusely for cyclin D1 and BCOR (in contrast to primitive neuroectodermal tumour), allowing the distinction.
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. The tumour has a destructive pattern of invasion of the myometrium and is associated with abundant myxoid matrix.
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. The tumour is composed of spindle cells set in a background stroma, closely resembling the appearance of a myxoid leiomyosarcoma.
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. In some areas of the tumour, spindle cells are compacted and associated with collagenous plaques.
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. The cells have scant to moderate eosinophilic cytoplasm and oval to spindle, relatively uniform nuclei. Mitotic activity is typically brisk.
BCOR internal tandem duplication (ITD) high-grade endometrial stromal sarcoma. The tumour shows a component of small round cells with a very minor component of spindle cells (upper left) embedded in a slightly myxoid stroma.
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. The tumour cells are diffusely positive for cyclin D1.
High-grade endometrial stromal sarcoma NOS. The tumour is a high-grade sarcoma that is associated with a low-grade sarcoma with the appearance of a low-grade endometrial stromal sarcoma (centre).

Q: A key immunohistochemical feature used to support the diagnosis of High-grade endometrial stromal sarcoma (such as the ZC3H7B-BCOR and YWHAE fusion subtypes) is diffuse nuclear positivity for BCOR and [...].
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. The tumour cells are diffusely positive for cyclin D1.
A: cyclin D1
Back Extra: High-grade endometrial stromal sarcoma
- Clinical: High-grade endometrial stromal sarcoma commonly presents with abnormal uterine bleeding, pelvic pain, or a uterine mass. Patients with BCOR ITD high-grade endometrial stromal sarcomas tend to be younger.
- Micro: Tumours may show expansile, permeative, or infiltrative growth with brisk mitotic activity and necrosis. Pseudorosette formation can be seen, which is a key feature for distinguishing it from other tumours.
- Ancillary: Essential features include monomorphic high-grade round and/or spindle cells, brisk mitotic activity, and cyclin D1 and BCOR positivity in YWHAE-NUTM2A/B or ZC3H7B-BCOR fusion cases.
Reference Gallery:
YWHAE-NUTM2A/B fusion–positive high-grade endometrial stromal sarcoma. There is diffuse growth of small round tumour cells associated with delicate vasculature.
YWHAE-NUTM2A/B fusion–positive high-grade endometrial stromal sarcoma. The tumour cells are small, with scant eosinophilic cytoplasm and round to angulated nuclei displaying granular to vesicular chromatin.
YWHAE-NUTM2A/B fusion–positive high-grade endometrial stromal sarcoma. Pseudorosette formation may be seen in these tumours and may cause confusion with primitive neuroectodermal tumour, confounded by the positivity of both primitive neuroectodermal tumour and high-grade endometrial stromal sarcoma for CD99. However, high-grade endometrial stromal sarcoma stains diffusely for cyclin D1 and BCOR (in contrast to primitive neuroectodermal tumour), allowing the distinction.
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. The tumour has a destructive pattern of invasion of the myometrium and is associated with abundant myxoid matrix.
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. The tumour is composed of spindle cells set in a background stroma, closely resembling the appearance of a myxoid leiomyosarcoma.
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. In some areas of the tumour, spindle cells are compacted and associated with collagenous plaques.
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. The cells have scant to moderate eosinophilic cytoplasm and oval to spindle, relatively uniform nuclei. Mitotic activity is typically brisk.
BCOR internal tandem duplication (ITD) high-grade endometrial stromal sarcoma. The tumour shows a component of small round cells with a very minor component of spindle cells (upper left) embedded in a slightly myxoid stroma.
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. The tumour cells are diffusely positive for cyclin D1.
High-grade endometrial stromal sarcoma NOS. The tumour is a high-grade sarcoma that is associated with a low-grade sarcoma with the appearance of a low-grade endometrial stromal sarcoma (centre).

Q: The ZC3H7B-BCOR fusion variant of High-grade endometrial stromal sarcoma characteristically exhibits a destructive growth pattern with spindle cells embedded in an abundant [...] matrix, closely resembling a myxoid leiomyosarcoma.
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. The tumour has a destructive pattern of invasion of the myometrium and is associated with abundant myxoid matrix.
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. The tumour is composed of spindle cells set in a background stroma, closely resembling the appearance of a myxoid leiomyosarcoma.
A: myxoid
Back Extra: High-grade endometrial stromal sarcoma
- Clinical: High-grade endometrial stromal sarcoma commonly presents with abnormal uterine bleeding, pelvic pain, or a uterine mass. Patients with BCOR ITD high-grade endometrial stromal sarcomas tend to be younger.
- Micro: Tumours may show expansile, permeative, or infiltrative growth with brisk mitotic activity and necrosis. Pseudorosette formation can be seen, which is a key feature for distinguishing it from other tumours.
- Ancillary: Essential features include monomorphic high-grade round and/or spindle cells, brisk mitotic activity, and cyclin D1 and BCOR positivity in YWHAE-NUTM2A/B or ZC3H7B-BCOR fusion cases.
Reference Gallery:
YWHAE-NUTM2A/B fusion–positive high-grade endometrial stromal sarcoma. There is diffuse growth of small round tumour cells associated with delicate vasculature.
YWHAE-NUTM2A/B fusion–positive high-grade endometrial stromal sarcoma. The tumour cells are small, with scant eosinophilic cytoplasm and round to angulated nuclei displaying granular to vesicular chromatin.
YWHAE-NUTM2A/B fusion–positive high-grade endometrial stromal sarcoma. Pseudorosette formation may be seen in these tumours and may cause confusion with primitive neuroectodermal tumour, confounded by the positivity of both primitive neuroectodermal tumour and high-grade endometrial stromal sarcoma for CD99. However, high-grade endometrial stromal sarcoma stains diffusely for cyclin D1 and BCOR (in contrast to primitive neuroectodermal tumour), allowing the distinction.
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. The tumour has a destructive pattern of invasion of the myometrium and is associated with abundant myxoid matrix.
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. The tumour is composed of spindle cells set in a background stroma, closely resembling the appearance of a myxoid leiomyosarcoma.
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. In some areas of the tumour, spindle cells are compacted and associated with collagenous plaques.
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. The cells have scant to moderate eosinophilic cytoplasm and oval to spindle, relatively uniform nuclei. Mitotic activity is typically brisk.
BCOR internal tandem duplication (ITD) high-grade endometrial stromal sarcoma. The tumour shows a component of small round cells with a very minor component of spindle cells (upper left) embedded in a slightly myxoid stroma.
ZC3H7B-BCOR fusion high-grade endometrial stromal sarcoma. The tumour cells are diffusely positive for cyclin D1.
High-grade endometrial stromal sarcoma NOS. The tumour is a high-grade sarcoma that is associated with a low-grade sarcoma with the appearance of a low-grade endometrial stromal sarcoma (centre).

Q: Microscopically, Leiomyosarcoma is characteristically composed of malignant [...] cells with ample eosinophilic cytoplasm, elongated nuclei, and moderate to severe atypia.
Leiomyosarcoma. Spindled leiomyosarcoma of the lower genital tract with marked cytological atypia and brisk mitotic activity, including atypical forms.
A: spindle
Back Extra: Leiomyosarcoma
- Clinical: Patients with leiomyosarcoma often present with vaginal bleeding or symptoms related to a mass, such as rectal or urinary tract issues.
- Micro: Leiomyosarcomas are characterized by spindle cells with ample eosinophilic cytoplasm, elongated nuclei, and features like moderate to severe cytological atypia and high mitotic count.
- Ancillary: Ancillary studies are generally not clinically relevant for the diagnosis of leiomyosarcoma.
Reference Gallery:
Leiomyosarcoma. Spindled leiomyosarcoma of the lower genital tract with marked cytological atypia and brisk mitotic activity, including atypical forms.

Q: A key histologic feature of Leiomyosarcoma that confirms malignancy in a smooth muscle tumor is the presence of marked cytological atypia and brisk [...], often including atypical forms.
Leiomyosarcoma. Spindled leiomyosarcoma of the lower genital tract with marked cytological atypia and brisk mitotic activity, including atypical forms.
A: mitotic activity
Back Extra: Leiomyosarcoma
- Clinical: Patients with leiomyosarcoma often present with vaginal bleeding or symptoms related to a mass, such as rectal or urinary tract issues.
- Micro: Leiomyosarcomas are characterized by spindle cells with ample eosinophilic cytoplasm, elongated nuclei, and features like moderate to severe cytological atypia and high mitotic count.
- Ancillary: Ancillary studies are generally not clinically relevant for the diagnosis of leiomyosarcoma.
Reference Gallery:
Leiomyosarcoma. Spindled leiomyosarcoma of the lower genital tract with marked cytological atypia and brisk mitotic activity, including atypical forms.

Q: Uterine leiomyosarcoma (conventional type) is typically composed of hyperchromatic spindle cells with significant pleomorphism and a characteristic sharp interface between viable and non-viable cells known as [...].
Uterine leiomyosarcoma, spindle. The tumour displays coagulative tumour cell necrosis, with a sharp interface between viable tumour (around feeding vessels) and non-viable tumour (with noticeable tumour cell ghosts).
Uterine leiomyosarcoma, spindle. Tumour cells show significant pleomorphism.
A: coagulative tumor cell necrosis
Back Extra: Uterine Leiomyosarcoma
- Clinical: Uterine leiomyosarcoma presents in women typically > 50 years old with symptoms such as vaginal bleeding, pelvic mass, or pelvic/abdominal pain.
- Micro: Spindle cell leiomyosarcomas are cellular with fascicular growth and enlarged hyperchromatic nuclei; myxoid leiomyosarcomas have a paucicellular appearance with abundant myxoid stroma.
- Ancillary: Tumour cells express desmin, h-caldesmon, and SMA, but expression can be weak or patchy, especially in poorly differentiated tumours.
Reference Gallery:
Uterine leiomyosarcoma, spindle. The tumour is cellular, with a fascicular growth and enlarged hyperchromatic nuclei visible at low-power magnification.
Uterine leiomyosarcoma, spindle. The tumour displays coagulative tumour cell necrosis, with a sharp interface between viable tumour (around feeding vessels) and non-viable tumour (with noticeable tumour cell ghosts).
Uterine leiomyosarcoma, spindle. Tumour cells show significant pleomorphism.
Uterine myxoid leiomyosarcoma. The tumour is characterized by an irregular infiltrative interface with the surrounding myometrium and appreciable myxoid background.
Uterine myxoid leiomyosarcoma. Pale myxoid stroma surrounds individual tumour cells, which are hyperchromatic and in this example moderately atypical.
Uterine epithelioid leiomyosarcoma. Tumour cells are round to ovoid; they have eosinophilic granular cytoplasm and irregularly shaped nuclei.
Uterine myxoid leiomyosarcoma. The tumour is hypocellular and lacks significant cytological atypia. It is associated with abundant myxoid matrix.
Uterine epithelioid leiomyosarcoma. Uterine mass with irregular interface with the myometrium, composed of round to polygonal cells with granular eosinophilic cytoplasm. Notice the presence of significant nuclear atypia and easily found mitoses. Cells were positive for desmin and h-caldesmon by immunohistochemistry.

Q: Unlike the cellular spindle variant, the [...] variant of uterine leiomyosarcoma often presents with a hypocellular appearance, abundant pale stroma, and an irregular, infiltrative interface with the surrounding myometrium.
Uterine myxoid leiomyosarcoma. The tumour is characterized by an irregular infiltrative interface with the surrounding myometrium and appreciable myxoid background.
Uterine myxoid leiomyosarcoma. The tumour is hypocellular and lacks significant cytological atypia. It is associated with abundant myxoid matrix.
A: myxoid
Back Extra: Uterine Leiomyosarcoma
- Clinical: Uterine leiomyosarcoma presents in women typically > 50 years old with symptoms such as vaginal bleeding, pelvic mass, or pelvic/abdominal pain.
- Micro: Spindle cell leiomyosarcomas are cellular with fascicular growth and enlarged hyperchromatic nuclei; myxoid leiomyosarcomas have a paucicellular appearance with abundant myxoid stroma.
- Ancillary: Tumour cells express desmin, h-caldesmon, and SMA, but expression can be weak or patchy, especially in poorly differentiated tumours.
Reference Gallery:
Uterine leiomyosarcoma, spindle. The tumour is cellular, with a fascicular growth and enlarged hyperchromatic nuclei visible at low-power magnification.
Uterine leiomyosarcoma, spindle. The tumour displays coagulative tumour cell necrosis, with a sharp interface between viable tumour (around feeding vessels) and non-viable tumour (with noticeable tumour cell ghosts).
Uterine leiomyosarcoma, spindle. Tumour cells show significant pleomorphism.
Uterine myxoid leiomyosarcoma. The tumour is characterized by an irregular infiltrative interface with the surrounding myometrium and appreciable myxoid background.
Uterine myxoid leiomyosarcoma. Pale myxoid stroma surrounds individual tumour cells, which are hyperchromatic and in this example moderately atypical.
Uterine epithelioid leiomyosarcoma. Tumour cells are round to ovoid; they have eosinophilic granular cytoplasm and irregularly shaped nuclei.
Uterine myxoid leiomyosarcoma. The tumour is hypocellular and lacks significant cytological atypia. It is associated with abundant myxoid matrix.
Uterine epithelioid leiomyosarcoma. Uterine mass with irregular interface with the myometrium, composed of round to polygonal cells with granular eosinophilic cytoplasm. Notice the presence of significant nuclear atypia and easily found mitoses. Cells were positive for desmin and h-caldesmon by immunohistochemistry.

Q: The epithelioid variant of uterine leiomyosarcoma consists of round to polygonal cells with granular eosinophilic cytoplasm that express smooth muscle immunohistochemical markers such as SMA, desmin, and [...].
Uterine epithelioid leiomyosarcoma. Tumour cells are round to ovoid; they have eosinophilic granular cytoplasm and irregularly shaped nuclei.
Uterine epithelioid leiomyosarcoma. Uterine mass with irregular interface with the myometrium, composed of round to polygonal cells with granular eosinophilic cytoplasm. Notice the presence of significant nuclear atypia and easily found mitoses. Cells were positive for desmin and h-caldesmon by immunohistochemistry.
A: h-caldesmon
Back Extra: Uterine Leiomyosarcoma
- Clinical: Uterine leiomyosarcoma presents in women typically > 50 years old with symptoms such as vaginal bleeding, pelvic mass, or pelvic/abdominal pain.
- Micro: Spindle cell leiomyosarcomas are cellular with fascicular growth and enlarged hyperchromatic nuclei; myxoid leiomyosarcomas have a paucicellular appearance with abundant myxoid stroma.
- Ancillary: Tumour cells express desmin, h-caldesmon, and SMA, but expression can be weak or patchy, especially in poorly differentiated tumours.
Reference Gallery:
Uterine leiomyosarcoma, spindle. The tumour is cellular, with a fascicular growth and enlarged hyperchromatic nuclei visible at low-power magnification.
Uterine leiomyosarcoma, spindle. The tumour displays coagulative tumour cell necrosis, with a sharp interface between viable tumour (around feeding vessels) and non-viable tumour (with noticeable tumour cell ghosts).
Uterine leiomyosarcoma, spindle. Tumour cells show significant pleomorphism.
Uterine myxoid leiomyosarcoma. The tumour is characterized by an irregular infiltrative interface with the surrounding myometrium and appreciable myxoid background.
Uterine myxoid leiomyosarcoma. Pale myxoid stroma surrounds individual tumour cells, which are hyperchromatic and in this example moderately atypical.
Uterine epithelioid leiomyosarcoma. Tumour cells are round to ovoid; they have eosinophilic granular cytoplasm and irregularly shaped nuclei.
Uterine myxoid leiomyosarcoma. The tumour is hypocellular and lacks significant cytological atypia. It is associated with abundant myxoid matrix.
Uterine epithelioid leiomyosarcoma. Uterine mass with irregular interface with the myometrium, composed of round to polygonal cells with granular eosinophilic cytoplasm. Notice the presence of significant nuclear atypia and easily found mitoses. Cells were positive for desmin and h-caldesmon by immunohistochemistry.

Q: Microscopically, Endometrioid Stromal Sarcoma of the Peritoneum typically infiltrates fibroconnective tissue as irregularly shaped islands of uniform cells that closely resemble [...].
Endometrioid stromal sarcoma of the peritoneum. Irregularly shaped islands of tumour infiltrate peritoneal fibroconnective tissue.
Endometrioid stromal sarcoma of the peritoneum. The tumour is composed of uniform, oval cells with scant cytoplasm associated with a proliferation of small blood vessels.
A: proliferative-type endometrial stroma
Back Extra: Endometrioid Stromal Sarcoma of the Peritoneum
- Clinical: Endometrioid stromal sarcoma of the peritoneum is rare and typically presents with signs and symptoms related to a pelvic/abdominal mass, gastrointestinal, and urinary symptoms.
- Micro: Histologically, the tumour shows a diffuse growth of uniform small cells with scant cytoplasm, bland oval nuclei, and variable mitotic activity, often resembling proliferative-type stroma.
- Ancillary: Immunohistochemistry is positive for CD10, ER, and PR, and may also express smooth muscle markers (actin and desmin) and keratins.
Reference Gallery:
Endometrioid stromal sarcoma of the peritoneum. Irregularly shaped islands of tumour infiltrate peritoneal fibroconnective tissue.
Endometrioid stromal sarcoma of the peritoneum. The tumour is composed of uniform, oval cells with scant cytoplasm associated with a proliferation of small blood vessels.

Q: A classic histologic feature of Endometrioid Stromal Sarcoma of the Peritoneum is that the uniform, oval neoplastic cells with scant cytoplasm are intimately associated with a prominent proliferation of [...].
Endometrioid stromal sarcoma of the peritoneum. The tumour is composed of uniform, oval cells with scant cytoplasm associated with a proliferation of small blood vessels.
A: small blood vessels
Back Extra: Endometrioid Stromal Sarcoma of the Peritoneum
- Clinical: Endometrioid stromal sarcoma of the peritoneum is rare and typically presents with signs and symptoms related to a pelvic/abdominal mass, gastrointestinal, and urinary symptoms.
- Micro: Histologically, the tumour shows a diffuse growth of uniform small cells with scant cytoplasm, bland oval nuclei, and variable mitotic activity, often resembling proliferative-type stroma.
- Ancillary: Immunohistochemistry is positive for CD10, ER, and PR, and may also express smooth muscle markers (actin and desmin) and keratins.
Reference Gallery:
Endometrioid stromal sarcoma of the peritoneum. Irregularly shaped islands of tumour infiltrate peritoneal fibroconnective tissue.
Endometrioid stromal sarcoma of the peritoneum. The tumour is composed of uniform, oval cells with scant cytoplasm associated with a proliferation of small blood vessels.

Q: Microscopically, Low-grade endometrial stromal sarcoma is characterized by densely cellular islands of uniform tumor cells that exhibit a [...] pattern of infiltration into the myometrium, often whorling around prominent arteriolar-type vessels.
Low-grade endometrial stromal sarcoma. The tumour shows a tongue-like pattern of infiltration of irregular islands of blue cells without associated stromal response.
Low-grade endometrial stromal sarcoma. Small uniform tumour cells have scant cytoplasm and oval nuclei, without cytological atypia. There is focal whorling of the tumour cells around arteriolar-type vessels, reminiscent of proliferative-phase endometrial stroma.
A: tongue-like
Back Extra: Low-grade endometrial stromal sarcoma
- Clinical: Patients often present with abnormal uterine bleeding, pelvic pain, and a uterine mass, with a mean age of 52 years.
- Micro: Characterized by irregular, densely cellular islands of tumour cells with a tongue-like pattern of infiltration into the myometrium and minimal cytological atypia.
- Ancillary: Diffuse strong expression of CD10, IFITM1, ER, and PR, and the presence of characteristic gene fusions such as JAZF1-SUZ12.
Reference Gallery:
Low-grade endometrial stromal sarcoma. The tumour shows a tongue-like pattern of infiltration of irregular islands of blue cells without associated stromal response.
Low-grade endometrial stromal sarcoma. Small uniform tumour cells have scant cytoplasm and oval nuclei, without cytological atypia. There is focal whorling of the tumour cells around arteriolar-type vessels, reminiscent of proliferative-phase endometrial stroma.
Low-grade endometrial stromal sarcoma. Prominent lymphovascular invasion is seen.
Low-grade endometrial stromal sarcoma. Smooth muscle differentiation seen as starburst morphology, with collagen bands radiating towards the periphery of the nodule embedding round cells, is present in a background of endometrial stromal neoplasia.
Low-grade endometrial stromal sarcoma. Macroscopic appearance. The large tan mass is associated with prominent permeative growth into the myometrium and vascular spaces, seen as worm-like plugs.
Low-grade endometrial stromal sarcoma. The tumour is hypocellular, in contrast to typical endometrial stromal tumours. It is associated with delicate background collagen and arteriolar-like vessels.
Low-grade endometrial stromal sarcoma. Extensive sex cord–like differentiation with retiform architecture is noted.

Q: Macroscopically, Low-grade endometrial stromal sarcoma often presents as a large, fleshy tan mass with permeative growth into the myometrium and vascular spaces, classically forming macroscopic [...].
Low-grade endometrial stromal sarcoma. Macroscopic appearance. The large tan mass is associated with prominent permeative growth into the myometrium and vascular spaces, seen as worm-like plugs.
A: worm-like plugs
Back Extra: Low-grade endometrial stromal sarcoma
- Clinical: Patients often present with abnormal uterine bleeding, pelvic pain, and a uterine mass, with a mean age of 52 years.
- Micro: Characterized by irregular, densely cellular islands of tumour cells with a tongue-like pattern of infiltration into the myometrium and minimal cytological atypia.
- Ancillary: Diffuse strong expression of CD10, IFITM1, ER, and PR, and the presence of characteristic gene fusions such as JAZF1-SUZ12.
Reference Gallery:
Low-grade endometrial stromal sarcoma. The tumour shows a tongue-like pattern of infiltration of irregular islands of blue cells without associated stromal response.
Low-grade endometrial stromal sarcoma. Small uniform tumour cells have scant cytoplasm and oval nuclei, without cytological atypia. There is focal whorling of the tumour cells around arteriolar-type vessels, reminiscent of proliferative-phase endometrial stroma.
Low-grade endometrial stromal sarcoma. Prominent lymphovascular invasion is seen.
Low-grade endometrial stromal sarcoma. Smooth muscle differentiation seen as starburst morphology, with collagen bands radiating towards the periphery of the nodule embedding round cells, is present in a background of endometrial stromal neoplasia.
Low-grade endometrial stromal sarcoma. Macroscopic appearance. The large tan mass is associated with prominent permeative growth into the myometrium and vascular spaces, seen as worm-like plugs.
Low-grade endometrial stromal sarcoma. The tumour is hypocellular, in contrast to typical endometrial stromal tumours. It is associated with delicate background collagen and arteriolar-like vessels.
Low-grade endometrial stromal sarcoma. Extensive sex cord–like differentiation with retiform architecture is noted.

Q: A 52-year-old woman presents with abnormal uterine bleeding and a pelvic mass. Histology demonstrates uniform cells with scant cytoplasm whorling around prominent arterioles, alongside prominent lymphovascular invasion. These classic morphological findings are highly characteristic of [...].
Low-grade endometrial stromal sarcoma. Small uniform tumour cells have scant cytoplasm and oval nuclei, without cytological atypia. There is focal whorling of the tumour cells around arteriolar-type vessels, reminiscent of proliferative-phase endometrial stroma.
Low-grade endometrial stromal sarcoma. Prominent lymphovascular invasion is seen.
A: Low-grade endometrial stromal sarcoma
Back Extra: Low-grade endometrial stromal sarcoma
- Clinical: Patients often present with abnormal uterine bleeding, pelvic pain, and a uterine mass, with a mean age of 52 years.
- Micro: Characterized by irregular, densely cellular islands of tumour cells with a tongue-like pattern of infiltration into the myometrium and minimal cytological atypia.
- Ancillary: Diffuse strong expression of CD10, IFITM1, ER, and PR, and the presence of characteristic gene fusions such as JAZF1-SUZ12.
Reference Gallery:
Low-grade endometrial stromal sarcoma. The tumour shows a tongue-like pattern of infiltration of irregular islands of blue cells without associated stromal response.
Low-grade endometrial stromal sarcoma. Small uniform tumour cells have scant cytoplasm and oval nuclei, without cytological atypia. There is focal whorling of the tumour cells around arteriolar-type vessels, reminiscent of proliferative-phase endometrial stroma.
Low-grade endometrial stromal sarcoma. Prominent lymphovascular invasion is seen.
Low-grade endometrial stromal sarcoma. Smooth muscle differentiation seen as starburst morphology, with collagen bands radiating towards the periphery of the nodule embedding round cells, is present in a background of endometrial stromal neoplasia.
Low-grade endometrial stromal sarcoma. Macroscopic appearance. The large tan mass is associated with prominent permeative growth into the myometrium and vascular spaces, seen as worm-like plugs.
Low-grade endometrial stromal sarcoma. The tumour is hypocellular, in contrast to typical endometrial stromal tumours. It is associated with delicate background collagen and arteriolar-like vessels.
Low-grade endometrial stromal sarcoma. Extensive sex cord–like differentiation with retiform architecture is noted.

Q: Microscopically, Undifferentiated Uterine Sarcoma is an aggressive tumor characterized by a diffuse growth pattern, marked nuclear pleomorphism, brisk mitotic activity, and a defining lack of any specific [...].
Undifferentiated uterine sarcoma. The tumour has a diffuse growth and exhibits marked nuclear pleomorphism, lacking any specific type of differentiation.
A: differentiation
Back Extra: Undifferentiated Uterine Sarcoma
- Clinical: Patients are typically postmenopausal and present with abnormal uterine bleeding, pelvic pain/pressure, and symptoms related to extrauterine disease.
- Micro: Undifferentiated uterine sarcomas typically display a destructive pattern of myometrial invasion with sheets of uniform or pleomorphic cells, marked nuclear pleomorphism, and brisk mitotic activity.
- Ancillary: Tumours are often positive for p53 and p16, and some may show positivity for ER and/or PR, as well as variable positivity for CD10.
Reference Gallery:
Undifferentiated uterine sarcoma. The tumour has a diffuse growth and exhibits marked nuclear pleomorphism, lacking any specific type of differentiation.

Q: Histologically, an Adenomatoid Tumor is characterized by pseudoglandular or slit-like spaces lined by attenuated [...] cells.
Adenomatoid tumour. Pseudoglandular spaces lined by attenuated mesothelial cells.
Adenomatoid tumour. On higher magnification, there are slit-like spaces lined by cuboidal cells.
A: mesothelial
Back Extra: Adenomatoid Tumor
- Clinical: Adenomatoid tumors are usually asymptomatic and incidentally discovered during surgeries for other conditions.
- Micro: These tumors show slit-like, tubular, or cystic branching spaces and solid areas intermixed with smooth muscle bundles.
- Ancillary: Adenomatoid tumors are genetically defined by somatic missense mutations in the TRAF7 gene and uniformly retain nuclear expression of BAP1.
Reference Gallery:
Adenomatoid tumour. Pseudoglandular spaces lined by attenuated mesothelial cells.
Adenomatoid tumour. On higher magnification, there are slit-like spaces lined by cuboidal cells.
Adenomatoid tumour. The tumour is poorly demarcated and centred in the wall of the fallopian tube.

Q: In the female genital tract, an Adenomatoid Tumor is frequently discovered incidentally as a poorly demarcated nodule centered in the wall of the [...].
Adenomatoid tumour. The tumour is poorly demarcated and centred in the wall of the fallopian tube.
A: fallopian tube
Back Extra: Adenomatoid Tumor
- Clinical: Adenomatoid tumors are usually asymptomatic and incidentally discovered during surgeries for other conditions.
- Micro: These tumors show slit-like, tubular, or cystic branching spaces and solid areas intermixed with smooth muscle bundles.
- Ancillary: Adenomatoid tumors are genetically defined by somatic missense mutations in the TRAF7 gene and uniformly retain nuclear expression of BAP1.
Reference Gallery:
Adenomatoid tumour. Pseudoglandular spaces lined by attenuated mesothelial cells.
Adenomatoid tumour. On higher magnification, there are slit-like spaces lined by cuboidal cells.
Adenomatoid tumour. The tumour is poorly demarcated and centred in the wall of the fallopian tube.

Q: Genetically, an Adenomatoid Tumor is defined by somatic missense mutations in the [...] gene.
Adenomatoid tumour. Pseudoglandular spaces lined by attenuated mesothelial cells.
Adenomatoid tumour. On higher magnification, there are slit-like spaces lined by cuboidal cells.
Adenomatoid tumour. The tumour is poorly demarcated and centred in the wall of the fallopian tube.
A: TRAF7
Back Extra: Adenomatoid Tumor
- Clinical: Adenomatoid tumors are usually asymptomatic and incidentally discovered during surgeries for other conditions.
- Micro: These tumors show slit-like, tubular, or cystic branching spaces and solid areas intermixed with smooth muscle bundles.
- Ancillary: Adenomatoid tumors are genetically defined by somatic missense mutations in the TRAF7 gene and uniformly retain nuclear expression of BAP1.
Reference Gallery:
Adenomatoid tumour. Pseudoglandular spaces lined by attenuated mesothelial cells.
Adenomatoid tumour. On higher magnification, there are slit-like spaces lined by cuboidal cells.
Adenomatoid tumour. The tumour is poorly demarcated and centred in the wall of the fallopian tube.

Q: In Carcinomas and sarcomas metastatic to the peritoneum, the histopathology includes a broad variety of malignancies that are morphologically identical to the [...].
Peritoneal metastatic cervical gastric-type adenocarcinoma. Metastatic glands from gastric-type adenocarcinoma of cervix invade the peritoneum.
Metastatic epithelioid angiosarcoma. Epithelioid cells infiltrating the omentum.
A: primary tumor
Back Extra: Carcinomas and sarcomas metastatic to the peritoneum
- Clinical: Clinical features often include abdominal discomfort, symptoms of intestinal obstruction, ascites, and weight loss.
- Micro: The histopathology is the same as the primary malignancy and includes a broad variety of carcinomas and sarcomas.
- Ancillary: Diagnostic molecular pathology may be useful to determine the origin of the tumour or to assess therapeutic targets.
Reference Gallery:
Peritoneal metastatic cervical gastric-type adenocarcinoma. Metastatic glands from gastric-type adenocarcinoma of cervix invade the peritoneum.
Metastatic epithelioid angiosarcoma. Epithelioid cells infiltrating the omentum.
Metastatic epithelioid angiosarcoma. The neoplastic cells are positive for CD34.

Q: When evaluating Carcinomas and sarcomas metastatic to the peritoneum, ancillary testing is often useful to determine the origin; for example, metastatic epithelioid angiosarcoma will typically show diffuse positivity for the vascular marker [...].
Metastatic epithelioid angiosarcoma. Epithelioid cells infiltrating the omentum.
Metastatic epithelioid angiosarcoma. The neoplastic cells are positive for CD34.
A: CD34
Back Extra: Carcinomas and sarcomas metastatic to the peritoneum
- Clinical: Clinical features often include abdominal discomfort, symptoms of intestinal obstruction, ascites, and weight loss.
- Micro: The histopathology is the same as the primary malignancy and includes a broad variety of carcinomas and sarcomas.
- Ancillary: Diagnostic molecular pathology may be useful to determine the origin of the tumour or to assess therapeutic targets.
Reference Gallery:
Peritoneal metastatic cervical gastric-type adenocarcinoma. Metastatic glands from gastric-type adenocarcinoma of cervix invade the peritoneum.
Metastatic epithelioid angiosarcoma. Epithelioid cells infiltrating the omentum.
Metastatic epithelioid angiosarcoma. The neoplastic cells are positive for CD34.

Q: In the clinical and gross evaluation of suspected Metastatic Tumors to the Ovary, the detection of [...] ovarian involvement strongly suggests secondary rather than primary neoplastic disease.
Metastatic melanoma involving both ovaries. Both ovaries are enlarged by dark multinodular masses. The ovarian serosa is smooth and uterus is not involved.
A: bilateral
Q: Metastatic Tumors to the Ovary
- Clinical: Bilateral ovarian involvement detected on imaging studies can suggest secondary involvement in [...].
- Micro: Signet-ring cells in [...] strongly favour metastatic disease, with rare exceptions.
- Ancillary: Immunohistochemical profiles of primary and metastatic ovarian carcinomas can help differentiate between primary and secondary lesions in [...].
Reference Gallery:
Low-grade appendiceal mucinous neoplasm involving ovary. Ovarian tissue is nearly completely replaced by gelatinous material.
Metastatic gastric adenocarcinoma. Poorly differentiated carcinoma with signet-ring cell morphology.
Metastatic pancreatic adenocarcinoma. Relatively simple small to medium-sized cystically dilated glands distributed in the ovarian stroma.
Ovarian involvement by low-grade appendiceal mucinous neoplasm. Note the cystic spaces lined by bland mucinous epithelium with foci of gland rupture and pseudomyxoma ovarii.
Metastatic colon adenocarcinoma. Typical garland pattern and dirty necrosis.
Metastatic colon adenocarcinoma. Confluent glandular pattern that may mimic primary ovarian mucinous or endometrioid carcinoma.
Metastatic HPV-associated endocervical adenocarcinoma. The architectural pattern mimics primary ovarian mucinous borderline tumour.
Metastatic appendiceal carcinoma. Poorly differentiated carcinoma with signet-ring cell morphology.
Metastatic breast carcinoma. Invasive breast carcinoma of no special type (NST). Note the tumour nests with cribriform growth within ovarian stroma.
Metastatic breast carcinoma. Lobular carcinoma. Tumour cells essentially replace the ovarian tissue in typical single-file arrangement.
Metastatic melanoma involving both ovaries. Both ovaries are enlarged by dark multinodular masses. The ovarian serosa is smooth and uterus is not involved.
Metastatic endocervical adenocarcinoma, gastric type. Cystically dilated glands are lined by mucinous epithelium resembling the gastric foveolar epithelium. Note the bland cytological features in some areas and notable atypia in others.
A: metastatic tumors to the ovary; metastatic tumors to the ovary; metastatic tumors to the ovary

Q: Microscopic identification of [...] cells in an ovarian mass (e.g., from a gastric or appendiceal primary) strongly favors a diagnosis of Metastatic Tumors to the Ovary over a primary ovarian carcinoma.
Metastatic gastric adenocarcinoma. Poorly differentiated carcinoma with signet-ring cell morphology.
Metastatic appendiceal carcinoma. Poorly differentiated carcinoma with signet-ring cell morphology.
A: signet-ring
Q: Metastatic Tumors to the Ovary
- Clinical: Bilateral ovarian involvement detected on imaging studies can suggest secondary involvement in [...].
- Micro: Signet-ring cells in [...] strongly favour metastatic disease, with rare exceptions.
- Ancillary: Immunohistochemical profiles of primary and metastatic ovarian carcinomas can help differentiate between primary and secondary lesions in [...].
Reference Gallery:
Low-grade appendiceal mucinous neoplasm involving ovary. Ovarian tissue is nearly completely replaced by gelatinous material.
Metastatic gastric adenocarcinoma. Poorly differentiated carcinoma with signet-ring cell morphology.
Metastatic pancreatic adenocarcinoma. Relatively simple small to medium-sized cystically dilated glands distributed in the ovarian stroma.
Ovarian involvement by low-grade appendiceal mucinous neoplasm. Note the cystic spaces lined by bland mucinous epithelium with foci of gland rupture and pseudomyxoma ovarii.
Metastatic colon adenocarcinoma. Typical garland pattern and dirty necrosis.
Metastatic colon adenocarcinoma. Confluent glandular pattern that may mimic primary ovarian mucinous or endometrioid carcinoma.
Metastatic HPV-associated endocervical adenocarcinoma. The architectural pattern mimics primary ovarian mucinous borderline tumour.
Metastatic appendiceal carcinoma. Poorly differentiated carcinoma with signet-ring cell morphology.
Metastatic breast carcinoma. Invasive breast carcinoma of no special type (NST). Note the tumour nests with cribriform growth within ovarian stroma.
Metastatic breast carcinoma. Lobular carcinoma. Tumour cells essentially replace the ovarian tissue in typical single-file arrangement.
Metastatic melanoma involving both ovaries. Both ovaries are enlarged by dark multinodular masses. The ovarian serosa is smooth and uterus is not involved.
Metastatic endocervical adenocarcinoma, gastric type. Cystically dilated glands are lined by mucinous epithelium resembling the gastric foveolar epithelium. Note the bland cytological features in some areas and notable atypia in others.
A: metastatic tumors to the ovary; metastatic tumors to the ovary; metastatic tumors to the ovary

Q: Microscopically, Central Primitive Neuroectodermal Tumour / CNS Embryonal Tumour is composed of small round blue cells that are frequently associated with foci of [...], which is consistent with neuronal or glial differentiation.
Central-type primitive neuroectodermal tumour. Small round cells are associated with foci of neuropil consistent with glial differentiation.
A: neuropil
Back Extra: Central Primitive Neuroectodermal Tumour / CNS Embryonal Tumour
- Clinical: Clinically, Central Primitive Neuroectodermal Tumour / CNS Embryonal Tumour presents with abnormal uterine bleeding, pelvic pain/pressure, and a uterine mass, and is rare, occurring in women with a median age of 55 years.
- Micro: Microscopically, these tumours are characterized by small round blue cells, often with neuronal/glial differentiation. Synaptophysin, chromogranin, and S100 are often positive, and GFAP is positive in approximately half of all cases.
- Ancillary: Ancillary studies show membranous CD99 and FLI1 expression is common, and the lack of EWSR1-FLI1 fusion or variants may be helpful in distinguishing this tumour from Ewing sarcoma.
Reference Gallery:
Central-type primitive neuroectodermal tumour. Small round cells are associated with foci of neuropil consistent with glial differentiation.

Q: Adenomyoma is characterized microscopically by a background of hypertrophied smooth muscle containing scattered [...].
Adenomyoma. A cavity lined by endometrial glandular epithelium and stroma overlying hypertrophied smooth muscle that mimics myometrium.
A: endometrial-type glands and stroma
Back Extra: Adenomyoma
- Clinical: Patients with adenomyoma may present with abdominal pain, a pelvic mass, and/or vaginal bleeding. Rarely, the tumour is discovered many years after hysterectomy and bilateral salpingo-oophorectomy.
- Micro: The mass consists of endometrial-type glands and stroma scattered throughout a background of smooth muscle. Cases may resemble a uterus (uterus-like mass).
- Ancillary: Ancillary studies are not clinically relevant in the diagnosis of adenomyoma.
Reference Gallery:
Adenomyoma. A cavity lined by endometrial glandular epithelium and stroma overlying hypertrophied smooth muscle that mimics myometrium.

Q: Microscopically, a(n) [...] is classically characterized by an admixture of endometrioid-type glands, stroma, and a predominance of smooth muscle.
Adenomyoma. Adenomyomas are typically composed of endometrioid-type glands surrounded by endometrioid-type stroma, in turn surrounded by smooth muscle.
Adenomyoma. Low-power view of a typical nodular adenomyoma, containing cystic spaces.
A: Adenomyoma of the Uterine Corpus
Back Extra: Adenomyoma of the Uterine Corpus
- Clinical: Adenomyomas of the uterine corpus most often present with abnormal vaginal bleeding.
- Micro: Characterized by an admixture of endometrioid-type glands, stroma, and smooth muscle. Smooth muscle typically predominates.
- Ancillary: Ancillary studies are not clinically relevant for diagnosing adenomyomas.
Reference Gallery:
Adenomyoma. These tumours are well circumscribed and predominantly solid, but they may show variably sized foci of haemorrhage and cyst formation.
Adenomyoma. Adenomyomas are typically composed of endometrioid-type glands surrounded by endometrioid-type stroma, in turn surrounded by smooth muscle.
Adenomyoma. Low-power view of a typical nodular adenomyoma, containing cystic spaces.

Q: On gross evaluation, a(n) [...] typically appears as a well-circumscribed, predominantly solid tumor that frequently contains variably sized foci of hemorrhage and cyst formation.
Adenomyoma. These tumours are well circumscribed and predominantly solid, but they may show variably sized foci of haemorrhage and cyst formation.
A: Adenomyoma of the Uterine Corpus
Back Extra: Adenomyoma of the Uterine Corpus
- Clinical: Adenomyomas of the uterine corpus most often present with abnormal vaginal bleeding.
- Micro: Characterized by an admixture of endometrioid-type glands, stroma, and smooth muscle. Smooth muscle typically predominates.
- Ancillary: Ancillary studies are not clinically relevant for diagnosing adenomyomas.
Reference Gallery:
Adenomyoma. These tumours are well circumscribed and predominantly solid, but they may show variably sized foci of haemorrhage and cyst formation.
Adenomyoma. Adenomyomas are typically composed of endometrioid-type glands surrounded by endometrioid-type stroma, in turn surrounded by smooth muscle.
Adenomyoma. Low-power view of a typical nodular adenomyoma, containing cystic spaces.

Q: Histologically, Atypical Polypoid Adenomyoma features irregular, architecturally complex endometrioid glands set within a benign myomatous or fibromyomatous stroma, frequently accompanied by [...].
Atypical polypoid adenomyoma. These lesions typically contain irregular, often architecturally complex endometrioid glands, often with squamous morules, set within myomatous or fibromyomatous stroma.
A: squamous morules
Back Extra: Atypical Polypoid Adenomyoma
- Clinical: Patients typically present with abnormal vaginal bleeding or infertility, and the lesion is most common in women of reproductive age.
- Micro: Histologically, the lesion contains irregular, architecturally complex endometrioid glands set within myomatous or fibromyomatous stroma, often with squamous morules.
- Ancillary: Immunohistochemical studies show stromal cells negative for h-caldesmon and positive for SATB2.
Reference Gallery:
Atypical polypoid adenomyoma. These lesions typically contain irregular, often architecturally complex endometrioid glands, often with squamous morules, set within myomatous or fibromyomatous stroma.
Atypical polypoid adenomyoma. The glandular component may show mild to moderate atypia, and the surrounding tissue is composed of benign cellular myomatous or fibromyomatous stroma.

Q: A characteristic histologic feature of Atypical Polypoid Adenomyoma is that its glandular component shows mild to moderate atypia, whereas the surrounding cellular stroma is characteristically benign and [...] or fibromyomatous in nature.
Atypical polypoid adenomyoma. The glandular component may show mild to moderate atypia, and the surrounding tissue is composed of benign cellular myomatous or fibromyomatous stroma.
A: myomatous
Back Extra: Atypical Polypoid Adenomyoma
- Clinical: Patients typically present with abnormal vaginal bleeding or infertility, and the lesion is most common in women of reproductive age.
- Micro: Histologically, the lesion contains irregular, architecturally complex endometrioid glands set within myomatous or fibromyomatous stroma, often with squamous morules.
- Ancillary: Immunohistochemical studies show stromal cells negative for h-caldesmon and positive for SATB2.
Reference Gallery:
Atypical polypoid adenomyoma. These lesions typically contain irregular, often architecturally complex endometrioid glands, often with squamous morules, set within myomatous or fibromyomatous stroma.
Atypical polypoid adenomyoma. The glandular component may show mild to moderate atypia, and the surrounding tissue is composed of benign cellular myomatous or fibromyomatous stroma.

Q: Patients with [...] are typically reproductive-age women presenting with abnormal vaginal bleeding or infertility, with biopsies revealing biphasic lesions of complex endometrioid glands and cellular fibromyomatous stroma.
Atypical polypoid adenomyoma. These lesions typically contain irregular, often architecturally complex endometrioid glands, often with squamous morules, set within myomatous or fibromyomatous stroma.
Atypical polypoid adenomyoma. The glandular component may show mild to moderate atypia, and the surrounding tissue is composed of benign cellular myomatous or fibromyomatous stroma.
A: Atypical Polypoid Adenomyoma
Back Extra: Atypical Polypoid Adenomyoma
- Clinical: Patients typically present with abnormal vaginal bleeding or infertility, and the lesion is most common in women of reproductive age.
- Micro: Histologically, the lesion contains irregular, architecturally complex endometrioid glands set within myomatous or fibromyomatous stroma, often with squamous morules.
- Ancillary: Immunohistochemical studies show stromal cells negative for h-caldesmon and positive for SATB2.
Reference Gallery:
Atypical polypoid adenomyoma. These lesions typically contain irregular, often architecturally complex endometrioid glands, often with squamous morules, set within myomatous or fibromyomatous stroma.
Atypical polypoid adenomyoma. The glandular component may show mild to moderate atypia, and the surrounding tissue is composed of benign cellular myomatous or fibromyomatous stroma.

Q: A characteristic microscopic finding in Adenosarcoma is a biphasic proliferation featuring benign glands surrounded by mitotically active, hypercellular stroma, often forming a [...] architecture.
Adenosarcoma. Low-power view of uterine adenosarcoma showing phyllodes-like architecture and increased cellularity surrounding glands.
A: phyllodes-like
Back Extra: Adenosarcoma
- Clinical: Patients often present with abnormal uterine bleeding and an enlarged uterus.
- Micro: Characteristic features include phyllodes-like architecture and hypercellular stroma surrounding benign glands.
- Ancillary: Immunohistochemical positivity for CD10, ER, and PR is common, with amplification of 8q13 and MYBL1 in some cases.
Reference Gallery:
Adenosarcoma. Subepithelial condensation of mitotically active hypercellular stroma is characteristic.
Adenosarcoma. High-power view of uterine adenosarcoma showing stromal mitotic activity.
Adenosarcoma. Low-power view of uterine adenosarcoma showing phyllodes-like architecture and increased cellularity surrounding glands.
Adenosarcoma. Multiple polypoid masses, some associated with haemorrhage, protrude into the endometrial cavity.

Q: In Adenosarcoma, a key histologic diagnostic clue is the presence of [...], characterized by significantly increased stromal cellularity and mitotic activity immediately surrounding the benign glands.
Adenosarcoma. Subepithelial condensation of mitotically active hypercellular stroma is characteristic.
Adenosarcoma. High-power view of uterine adenosarcoma showing stromal mitotic activity.
A: subepithelial condensation
Back Extra: Adenosarcoma
- Clinical: Patients often present with abnormal uterine bleeding and an enlarged uterus.
- Micro: Characteristic features include phyllodes-like architecture and hypercellular stroma surrounding benign glands.
- Ancillary: Immunohistochemical positivity for CD10, ER, and PR is common, with amplification of 8q13 and MYBL1 in some cases.
Reference Gallery:
Adenosarcoma. Subepithelial condensation of mitotically active hypercellular stroma is characteristic.
Adenosarcoma. High-power view of uterine adenosarcoma showing stromal mitotic activity.
Adenosarcoma. Low-power view of uterine adenosarcoma showing phyllodes-like architecture and increased cellularity surrounding glands.
Adenosarcoma. Multiple polypoid masses, some associated with haemorrhage, protrude into the endometrial cavity.

Q: Grossly, uterine Adenosarcoma frequently presents as large, multiple [...] protruding into the endometrial cavity, often associated with hemorrhage.
Adenosarcoma. Multiple polypoid masses, some associated with haemorrhage, protrude into the endometrial cavity.
A: polypoid masses
Back Extra: Adenosarcoma
- Clinical: Patients often present with abnormal uterine bleeding and an enlarged uterus.
- Micro: Characteristic features include phyllodes-like architecture and hypercellular stroma surrounding benign glands.
- Ancillary: Immunohistochemical positivity for CD10, ER, and PR is common, with amplification of 8q13 and MYBL1 in some cases.
Reference Gallery:
Adenosarcoma. Subepithelial condensation of mitotically active hypercellular stroma is characteristic.
Adenosarcoma. High-power view of uterine adenosarcoma showing stromal mitotic activity.
Adenosarcoma. Low-power view of uterine adenosarcoma showing phyllodes-like architecture and increased cellularity surrounding glands.
Adenosarcoma. Multiple polypoid masses, some associated with haemorrhage, protrude into the endometrial cavity.

Q: The defining histologic feature of Uterine Tumour Resembling Ovarian Sex Cord Tumour is the presence of bland cells with pale to eosinophilic cytoplasm arranged in patterns that mimic gonadal elements, including interanastomosing trabeculae, cords, and [...].
Uterine tumour resembling an ovarian sex cord tumour. The tumour shows interanastomosing trabeculae growing between endometrial glands.
Uterine tumour resembling an ovarian sex cord tumour. Most tumour cells show eosinophilic cytoplasm, but some have abundant pale vacuolated cytoplasm. Nuclei are small and cytologically bland.
Uterine tumour resembling an ovarian sex cord tumour. Tumour cells form cords and tubules.
A: tubules
Back Extra: Uterine Tumour Resembling Ovarian Sex Cord Tumour
- Clinical: Uterine tumour resembling ovarian sex cord tumour typically occurs in middle-aged women (mean age: 50 years) and often presents with abnormal vaginal bleeding or pelvic pain.
- Micro: Histologically, the tumour shows a variety of growth patterns including sheets, cords, nests, insulae, trabeculae, or tubules, with cells having scant to abundant cytoplasm and minimal cytological atypia.
- Ancillary: Tumours have a polyphenotypic immunohistochemical profile, with variable positivity for sex cord markers (inhibin, calretinin, WT1, CD56, CD99, SF1, FOXL2, and melan-A).
Reference Gallery:
Uterine tumour resembling an ovarian sex cord tumour. The tumour shows interanastomosing trabeculae growing between endometrial glands.
Uterine tumour resembling an ovarian sex cord tumour. Most tumour cells show eosinophilic cytoplasm, but some have abundant pale vacuolated cytoplasm. Nuclei are small and cytologically bland.
Uterine tumour resembling an ovarian sex cord tumour. Tumour cells form cords and tubules.
Uterine tumour resembling an ovarian sex cord tumour. Melan-A is positive in many of the tumour cells.

Q: Immunohistochemically, Uterine Tumour Resembling Ovarian Sex Cord Tumour has a polyphenotypic profile that characteristically includes variable positivity for sex cord markers such as inhibin, calretinin, and [...].
Uterine tumour resembling an ovarian sex cord tumour. Melan-A is positive in many of the tumour cells.
A: melan-A
Back Extra: Uterine Tumour Resembling Ovarian Sex Cord Tumour
- Clinical: Uterine tumour resembling ovarian sex cord tumour typically occurs in middle-aged women (mean age: 50 years) and often presents with abnormal vaginal bleeding or pelvic pain.
- Micro: Histologically, the tumour shows a variety of growth patterns including sheets, cords, nests, insulae, trabeculae, or tubules, with cells having scant to abundant cytoplasm and minimal cytological atypia.
- Ancillary: Tumours have a polyphenotypic immunohistochemical profile, with variable positivity for sex cord markers (inhibin, calretinin, WT1, CD56, CD99, SF1, FOXL2, and melan-A).
Reference Gallery:
Uterine tumour resembling an ovarian sex cord tumour. The tumour shows interanastomosing trabeculae growing between endometrial glands.
Uterine tumour resembling an ovarian sex cord tumour. Most tumour cells show eosinophilic cytoplasm, but some have abundant pale vacuolated cytoplasm. Nuclei are small and cytologically bland.
Uterine tumour resembling an ovarian sex cord tumour. Tumour cells form cords and tubules.
Uterine tumour resembling an ovarian sex cord tumour. Melan-A is positive in many of the tumour cells.

Q: Microscopically, [...] is characterized by enlarged, hobnail cells with clear or eosinophilic cytoplasm and highly atypical nuclei, typically seen in the setting of pregnancy or gestational trophoblastic disease.
Arias-Stella reaction. Most of the affected cells in this gland have eosinophilic cytoplasm. Many also have nuclear pseudoinclusions.
Arias-Stella reaction. The epithelial cells have clear cytoplasm and enlarged and irregular nuclei, with smudged chromatin.
A: Arias-Stella Reaction
Back Extra: Arias-Stella Reaction
- Clinical: The Arias-Stella reaction is associated with pregnancy, gestational trophoblastic disease, or high doses of progestins. Serum hCG is elevated in gestational cases.
- Micro: The reaction is characterized by enlarged, hobnail cells with abundant eosinophilic or glycogen-rich clear cytoplasm and highly atypical nuclei with smudged or vesicular chromatin.
- Ancillary: Immunohistochemical stains have limited value due to overlap with clear cell carcinoma.
Reference Gallery:
Arias-Stella reaction. Most of the affected cells in this gland have eosinophilic cytoplasm. Many also have nuclear pseudoinclusions.
Arias-Stella reaction. The epithelial cells have clear cytoplasm and enlarged and irregular nuclei, with smudged chromatin.

Q: The highly atypical, irregular nuclei characteristic of Arias-Stella Reaction classically exhibit vesicular or [...] chromatin.
Arias-Stella reaction. The epithelial cells have clear cytoplasm and enlarged and irregular nuclei, with smudged chromatin.
A: smudged
Back Extra: Arias-Stella Reaction
- Clinical: The Arias-Stella reaction is associated with pregnancy, gestational trophoblastic disease, or high doses of progestins. Serum hCG is elevated in gestational cases.
- Micro: The reaction is characterized by enlarged, hobnail cells with abundant eosinophilic or glycogen-rich clear cytoplasm and highly atypical nuclei with smudged or vesicular chromatin.
- Ancillary: Immunohistochemical stains have limited value due to overlap with clear cell carcinoma.
Reference Gallery:
Arias-Stella reaction. Most of the affected cells in this gland have eosinophilic cytoplasm. Many also have nuclear pseudoinclusions.
Arias-Stella reaction. The epithelial cells have clear cytoplasm and enlarged and irregular nuclei, with smudged chromatin.

Q: In Endometrial Metaplasia, the [...] variant features single-layered, mitotically inactive cuboidal cells projecting over the surface or into gland lumina, characterized by scant cytoplasm and enlarged hyperchromatic nuclei.
Endometrial metaplasia. Hobnail metaplasia. The epithelial cells project over the surface or into gland lumina. They have scant cytoplasm and enlarged hyperchromatic nuclei, without mitotic activity.
A: hobnail
Back Extra: Endometrial Metaplasia
- Clinical: Endometrial metaplasia is commonly seen in postmenopausal women and those who have received oral estrogen therapy.
- Micro: Hobnail metaplasia features single-layered, mitotically inactive cuboidal cells projecting over the surface with scant cytoplasm and enlarged hyperchromatic nuclei.
- Ancillary: Immunoprofiling may show β-catenin+, CDX2+, CD10+, p16+, EMA−, ER−, and p63−.
Reference Gallery:
Endometrial metaplasia. Syncytial papillary change. Stroma-free papillae are composed of eosinophilic cells without atypia. Neutrophilic infiltrate is prominent.
Endometrial metaplasia. Eosinophilic metaplasia. The glandular epithelial cells have abundant oxyphilic cytoplasm.
Endometrial metaplasia. Ciliated cell metaplasia. The surface epithelial cells all have prominent apical cilia.
Endometrial metaplasia. Tubal metaplasia. The epithelium is an admixture of ciliated columnar cells and intercalated cells.
Endometrial metaplasia. Hobnail metaplasia. The epithelial cells project over the surface or into gland lumina. They have scant cytoplasm and enlarged hyperchromatic nuclei, without mitotic activity.
Endometrial metaplasia. Mucinous metaplasia. The cells have basally located nuclei and prominent cytoplasmic vacuoles.
Endometrial metaplasia. Squamous metaplasia. The mature squamous epithelium lacks cytological atypia.
Endometrial metaplasia. Morular metaplasia. The gland lumina contain nests of immature, round to spindled epithelial cells.
Endometrial metaplasia. Clear cell metaplasia. There is abundant clear cytoplasm, which is rich in glycogen.

Q: A distinct morphological pattern of Endometrial Metaplasia is the [...] variant, which is characterized by gland lumina containing solid nests of immature, round to spindled epithelial cells.
Endometrial metaplasia. Morular metaplasia. The gland lumina contain nests of immature, round to spindled epithelial cells.
A: morular
Back Extra: Endometrial Metaplasia
- Clinical: Endometrial metaplasia is commonly seen in postmenopausal women and those who have received oral estrogen therapy.
- Micro: Hobnail metaplasia features single-layered, mitotically inactive cuboidal cells projecting over the surface with scant cytoplasm and enlarged hyperchromatic nuclei.
- Ancillary: Immunoprofiling may show β-catenin+, CDX2+, CD10+, p16+, EMA−, ER−, and p63−.
Reference Gallery:
Endometrial metaplasia. Syncytial papillary change. Stroma-free papillae are composed of eosinophilic cells without atypia. Neutrophilic infiltrate is prominent.
Endometrial metaplasia. Eosinophilic metaplasia. The glandular epithelial cells have abundant oxyphilic cytoplasm.
Endometrial metaplasia. Ciliated cell metaplasia. The surface epithelial cells all have prominent apical cilia.
Endometrial metaplasia. Tubal metaplasia. The epithelium is an admixture of ciliated columnar cells and intercalated cells.
Endometrial metaplasia. Hobnail metaplasia. The epithelial cells project over the surface or into gland lumina. They have scant cytoplasm and enlarged hyperchromatic nuclei, without mitotic activity.
Endometrial metaplasia. Mucinous metaplasia. The cells have basally located nuclei and prominent cytoplasmic vacuoles.
Endometrial metaplasia. Squamous metaplasia. The mature squamous epithelium lacks cytological atypia.
Endometrial metaplasia. Morular metaplasia. The gland lumina contain nests of immature, round to spindled epithelial cells.
Endometrial metaplasia. Clear cell metaplasia. There is abundant clear cytoplasm, which is rich in glycogen.

Q: In Endometrial Metaplasia, the [...] variant consists of an epithelium composed of an admixture of ciliated columnar cells and intercalated (peg) cells.
Endometrial metaplasia. Tubal metaplasia. The epithelium is an admixture of ciliated columnar cells and intercalated cells.
A: tubal
Back Extra: Endometrial Metaplasia
- Clinical: Endometrial metaplasia is commonly seen in postmenopausal women and those who have received oral estrogen therapy.
- Micro: Hobnail metaplasia features single-layered, mitotically inactive cuboidal cells projecting over the surface with scant cytoplasm and enlarged hyperchromatic nuclei.
- Ancillary: Immunoprofiling may show β-catenin+, CDX2+, CD10+, p16+, EMA−, ER−, and p63−.
Reference Gallery:
Endometrial metaplasia. Syncytial papillary change. Stroma-free papillae are composed of eosinophilic cells without atypia. Neutrophilic infiltrate is prominent.
Endometrial metaplasia. Eosinophilic metaplasia. The glandular epithelial cells have abundant oxyphilic cytoplasm.
Endometrial metaplasia. Ciliated cell metaplasia. The surface epithelial cells all have prominent apical cilia.
Endometrial metaplasia. Tubal metaplasia. The epithelium is an admixture of ciliated columnar cells and intercalated cells.
Endometrial metaplasia. Hobnail metaplasia. The epithelial cells project over the surface or into gland lumina. They have scant cytoplasm and enlarged hyperchromatic nuclei, without mitotic activity.
Endometrial metaplasia. Mucinous metaplasia. The cells have basally located nuclei and prominent cytoplasmic vacuoles.
Endometrial metaplasia. Squamous metaplasia. The mature squamous epithelium lacks cytological atypia.
Endometrial metaplasia. Morular metaplasia. The gland lumina contain nests of immature, round to spindled epithelial cells.
Endometrial metaplasia. Clear cell metaplasia. There is abundant clear cytoplasm, which is rich in glycogen.

Q: In Vaginal Cysts, the mesonephric (Gartner duct) variant is characteristically lined by [...] epithelium lacking cytoplasmic mucin.
Mesonephric (Gartner duct) cyst. Mesonephric cysts are lined by non-ciliated, cuboidal or flattened cells without cytoplasmic mucin.
A: non-ciliated cuboidal to flattened
Back Extra: Vaginal Cysts
- Clinical: Vaginal cysts are most commonly diagnosed in adults (average patient age: 38 years) and may present as asymptomatic or with symptoms like a lump, pain, or urinary issues.
- Micro: Müllerian cysts are lined by mucinous, tubal, or endometrioid-type epithelium, while mesonephric cysts are lined by non-mucinous, non-ciliated cuboidal to flattened epithelium.
- Ancillary: Immunohistochemically, Müllerian cysts are positive for PAX8, ER, and PR, whereas mesonephric cysts are negative for hormone receptors and positive for GATA3.
Reference Gallery:
Mesonephric (Gartner duct) cyst. Mesonephric cysts are lined by non-ciliated, cuboidal or flattened cells without cytoplasmic mucin.

Q: In the context of Vaginal Cysts, the mesonephric variant is classically known by the eponym [...] cyst.
Mesonephric (Gartner duct) cyst. Mesonephric cysts are lined by non-ciliated, cuboidal or flattened cells without cytoplasmic mucin.
A: Gartner duct
Back Extra: Vaginal Cysts
- Clinical: Vaginal cysts are most commonly diagnosed in adults (average patient age: 38 years) and may present as asymptomatic or with symptoms like a lump, pain, or urinary issues.
- Micro: Müllerian cysts are lined by mucinous, tubal, or endometrioid-type epithelium, while mesonephric cysts are lined by non-mucinous, non-ciliated cuboidal to flattened epithelium.
- Ancillary: Immunohistochemically, Müllerian cysts are positive for PAX8, ER, and PR, whereas mesonephric cysts are negative for hormone receptors and positive for GATA3.
Reference Gallery:
Mesonephric (Gartner duct) cyst. Mesonephric cysts are lined by non-ciliated, cuboidal or flattened cells without cytoplasmic mucin.

Q: The microscopic finding of bland mucinous or tuboendometrioid glands replacing the normal squamous epithelium or located within the superficial stroma of the vagina is diagnostic of [...].
Vaginal adenosis. The lesion is composed of bland mucinous glands.
A: Vaginal Adenosis
Back Extra: Vaginal Adenosis
- Clinical: Vaginal adenosis can occur over a wide age range and may present with vaginal discharge, pain, or be discovered incidentally.
- Micro: Histology shows glands located within the superficial stroma or replacing the squamous epithelium, often with a mucinous or tuboendometrioid pattern.
- Ancillary: Ancillary studies are not clinically relevant in the diagnosis of vaginal adenosis.
Reference Gallery:
Vaginal adenosis. The lesion is composed of bland mucinous glands.

Q: In Vaginal Adenosis, the characteristic glands replacing the squamous epithelium most frequently demonstrate a tuboendometrioid or bland [...] pattern.
Vaginal adenosis. The lesion is composed of bland mucinous glands.
A: mucinous
Back Extra: Vaginal Adenosis
- Clinical: Vaginal adenosis can occur over a wide age range and may present with vaginal discharge, pain, or be discovered incidentally.
- Micro: Histology shows glands located within the superficial stroma or replacing the squamous epithelium, often with a mucinous or tuboendometrioid pattern.
- Ancillary: Ancillary studies are not clinically relevant in the diagnosis of vaginal adenosis.
Reference Gallery:
Vaginal adenosis. The lesion is composed of bland mucinous glands.

Q: Histologically, mixed tumor of the vagina typically features a biphasic population consisting of epithelial elements (such as glands) admixed with bland [...] cells.
Mixed tumour of the vagina. The tumour is composed of benign spindled cells forming cords, as well as glandular structures.
A: spindle
Back Extra: Mixed Tumour of the Vagina
- Clinical: Mixed tumour of the vagina typically affects patients with a mean age of 40 years and is often asymptomatic or presents with nonspecific symptoms related to a mass.
- Micro: The tumour is composed of an admixture of spindle cells and epithelial elements, including glandular (mucinous) and/or mature squamous epithelium, with minimal nuclear atypia and low mitotic activity.
- Ancillary: Ancillary studies show coexpression of epithelial and mesenchymal markers, such as AE1/AE3, CK7, EMA, CD10, SMA, desmin, h-caldesmon, WT1, calretinin, BCL2, and CD34.
Reference Gallery:
Mixed tumour of the vagina. The tumour is composed of benign spindled cells forming cords, as well as glandular structures.
Mixed tumour of the vagina. Mature squamous epithelium is closely admixed with bland spindle-shaped cells.

Q: In mixed tumor of the vagina, the benign stromal component is intimately admixed with mature epithelial elements, which most commonly include mucinous glands and/or mature [...] epithelium.
Mixed tumour of the vagina. Mature squamous epithelium is closely admixed with bland spindle-shaped cells.
A: squamous
Back Extra: Mixed Tumour of the Vagina
- Clinical: Mixed tumour of the vagina typically affects patients with a mean age of 40 years and is often asymptomatic or presents with nonspecific symptoms related to a mass.
- Micro: The tumour is composed of an admixture of spindle cells and epithelial elements, including glandular (mucinous) and/or mature squamous epithelium, with minimal nuclear atypia and low mitotic activity.
- Ancillary: Ancillary studies show coexpression of epithelial and mesenchymal markers, such as AE1/AE3, CK7, EMA, CD10, SMA, desmin, h-caldesmon, WT1, calretinin, BCL2, and CD34.
Reference Gallery:
Mixed tumour of the vagina. The tumour is composed of benign spindled cells forming cords, as well as glandular structures.
Mixed tumour of the vagina. Mature squamous epithelium is closely admixed with bland spindle-shaped cells.

Q: Histologically, Villous Adenoma of the vagina features exophytic villiform structures lined by tall columnar epithelium with elongated hyperchromatic nuclei, morphologically resembling a(n) [...] adenoma.
Villous adenoma. Exophytic villiform structures are lined by tall columnar epithelium with elongated hyperchromatic nuclei, the feature resembling a colorectal adenoma.
A: colorectal
Back Extra: Villous Adenoma
- Clinical: Villous adenomas of the vagina are extremely rare, typically presenting in adults aged 19-80 years with a vaginal mass or abnormal vaginal bleeding.
- Micro: Histologically, villous adenomas show villiform and/or tubular structures lined by columnar epithelium with atypical pseudostratified elongated hyperchromatic nuclei, often containing scattered goblet cells.
- Ancillary: Immunohistochemically, villous adenomas are usually positive for CK20 and CDX2, with variable CK7 expression.
Reference Gallery:
Villous adenoma. Exophytic villiform structures are lined by tall columnar epithelium with elongated hyperchromatic nuclei, the feature resembling a colorectal adenoma.

Q: Cytologically, the tall columnar epithelium lining the exophytic structures in a Villous Adenoma is characterized by atypical, pseudostratified, elongated, and [...] nuclei.
Villous adenoma. Exophytic villiform structures are lined by tall columnar epithelium with elongated hyperchromatic nuclei, the feature resembling a colorectal adenoma.
A: hyperchromatic
Back Extra: Villous Adenoma
- Clinical: Villous adenomas of the vagina are extremely rare, typically presenting in adults aged 19-80 years with a vaginal mass or abnormal vaginal bleeding.
- Micro: Histologically, villous adenomas show villiform and/or tubular structures lined by columnar epithelium with atypical pseudostratified elongated hyperchromatic nuclei, often containing scattered goblet cells.
- Ancillary: Immunohistochemically, villous adenomas are usually positive for CK20 and CDX2, with variable CK7 expression.
Reference Gallery:
Villous adenoma. Exophytic villiform structures are lined by tall columnar epithelium with elongated hyperchromatic nuclei, the feature resembling a colorectal adenoma.

Q: A [...] is characterized histologically by nests of bland squamous epithelium with small tubules at the periphery, often set within a collagenous stroma.
Vaginal tubulosquamous polyp. Low-power view showing nests of epithelium within a collagenous stroma.
Vaginal tubulosquamous polyp. High-power view showing nests of squamous epithelium with small tubules around the periphery.
A: Tubulosquamous Polyp
Back Extra: Tubulosquamous Polyp
- Clinical: Tubulosquamous polyps are typically an incidental finding in patients within a wide age range (39–78 years) with unknown etiology.
- Micro: The polyps are covered by squamous epithelium and contain nests of bland squamous epithelium with small tubules at the periphery, often with a collagenous stroma.
- Ancillary: Immunohistochemically, the inner layer of the tubules is positive for prostatic markers (PSA, PAP, NKX3-1), while the squamous elements are positive for p63 and GATA3.
Reference Gallery:
Vaginal tubulosquamous polyp. Low-power view showing nests of epithelium within a collagenous stroma.
Vaginal tubulosquamous polyp. High-power view showing nests of squamous epithelium with small tubules around the periphery.

Q: In a Tubulosquamous Polyp, high-power histologic examination characteristically reveals nests of bland squamous epithelium with small [...] around the periphery.
Vaginal tubulosquamous polyp. High-power view showing nests of squamous epithelium with small tubules around the periphery.
A: tubules
Back Extra: Tubulosquamous Polyp
- Clinical: Tubulosquamous polyps are typically an incidental finding in patients within a wide age range (39–78 years) with unknown etiology.
- Micro: The polyps are covered by squamous epithelium and contain nests of bland squamous epithelium with small tubules at the periphery, often with a collagenous stroma.
- Ancillary: Immunohistochemically, the inner layer of the tubules is positive for prostatic markers (PSA, PAP, NKX3-1), while the squamous elements are positive for p63 and GATA3.
Reference Gallery:
Vaginal tubulosquamous polyp. Low-power view showing nests of epithelium within a collagenous stroma.
Vaginal tubulosquamous polyp. High-power view showing nests of squamous epithelium with small tubules around the periphery.

Q: Morphologically, Adenocarcinoma of Skene gland origin closely resembles [...], frequently demonstrating a cribriform pattern or well-formed glands lined by cuboidal cells with clear to eosinophilic cytoplasm.
Adenocarcinoma of Skene gland origin. The tumour is composed of small glands with cuboidal cells with clear to eosinophilic cytoplasm.
A: acinar prostatic adenocarcinoma
Back Extra: Adenocarcinoma of Skene gland origin
- Clinical: Adenocarcinoma of Skene gland origin typically presents with a vaginal mass, and less frequently with haematuria or incontinence. Serum PSA may be elevated.
- Micro: Morphologically, the tumour resembles acinar prostatic adenocarcinoma, with well-formed to poorly formed glands lined by cuboidal or columnar epithelium, and a cribriform pattern is common.
- Ancillary: Immunohistochemically, the tumour is positive for prostatic markers such as PSA, PAP, NKX3-1, P501S, AMACR, and PIN4 cocktail.
Reference Gallery:
Adenocarcinoma of Skene gland origin. The tumour is composed of small glands with cuboidal cells with clear to eosinophilic cytoplasm.
Adenocarcinoma of Skene gland origin. Tumour cells are positive for PSA.

Q: Immunohistochemically, Adenocarcinoma of Skene gland origin is characteristically positive for male prostate markers such as PAP, NKX3-1, AMACR, and [...].
Adenocarcinoma of Skene gland origin. Tumour cells are positive for PSA.
A: PSA
Back Extra: Adenocarcinoma of Skene gland origin
- Clinical: Adenocarcinoma of Skene gland origin typically presents with a vaginal mass, and less frequently with haematuria or incontinence. Serum PSA may be elevated.
- Micro: Morphologically, the tumour resembles acinar prostatic adenocarcinoma, with well-formed to poorly formed glands lined by cuboidal or columnar epithelium, and a cribriform pattern is common.
- Ancillary: Immunohistochemically, the tumour is positive for prostatic markers such as PSA, PAP, NKX3-1, P501S, AMACR, and PIN4 cocktail.
Reference Gallery:
Adenocarcinoma of Skene gland origin. The tumour is composed of small glands with cuboidal cells with clear to eosinophilic cytoplasm.
Adenocarcinoma of Skene gland origin. Tumour cells are positive for PSA.

Q: A 45-year-old patient presents with a vaginal mass. Biopsy demonstrates a neoplasm with papillary and glandular architecture composed of columnar cells with mucin-poor cytoplasm, easily identifiable mitoses, and p16 overexpression. The most likely diagnosis is [...].
HPV-associated adenocarcinoma of the vagina. HPV-associated adenocarcinoma of the vagina composed of columnar cells with mucin-poor cytoplasm and easily identifiable mitoses and apoptosis.
A: Adenocarcinoma, HPV-associated, of the vagina
Back Extra: Adenocarcinoma, HPV-associated, of the vagina
- Clinical: Adenocarcinoma, HPV-associated, of the vagina typically presents in patients aged 38-51 years and is often associated with a vaginal mass.
- Micro: Histologically, the neoplasm exhibits papillary, villoglandular, and glandular architecture with columnar cells showing mucin-poor cytoplasm and easily identifiable mitoses and apoptosis.
- Ancillary: p16 overexpression is characteristic of this neoplasm, and HPV detection is desirable for confirmation.
Reference Gallery:
HPV-associated adenocarcinoma of the vagina. HPV-associated adenocarcinoma of the vagina composed of columnar cells with mucin-poor cytoplasm and easily identifiable mitoses and apoptosis.

Q: Histologically, Adenocarcinoma, HPV-associated, of the vagina features papillary, villoglandular, and glandular architecture lined by columnar cells with characteristically [...] cytoplasm, along with numerous mitoses and apoptotic bodies.
HPV-associated adenocarcinoma of the vagina. HPV-associated adenocarcinoma of the vagina composed of columnar cells with mucin-poor cytoplasm and easily identifiable mitoses and apoptosis.
A: mucin-poor
Back Extra: Adenocarcinoma, HPV-associated, of the vagina
- Clinical: Adenocarcinoma, HPV-associated, of the vagina typically presents in patients aged 38-51 years and is often associated with a vaginal mass.
- Micro: Histologically, the neoplasm exhibits papillary, villoglandular, and glandular architecture with columnar cells showing mucin-poor cytoplasm and easily identifiable mitoses and apoptosis.
- Ancillary: p16 overexpression is characteristic of this neoplasm, and HPV detection is desirable for confirmation.
Reference Gallery:
HPV-associated adenocarcinoma of the vagina. HPV-associated adenocarcinoma of the vagina composed of columnar cells with mucin-poor cytoplasm and easily identifiable mitoses and apoptosis.

Q: Histologically, Adenosarcoma of the vagina is characterized by prominent periglandular stromal cuffing and broad, [...] intraglandular projections.
Adenosarcoma. There is a broad phyllodes-like intraglandular projection and periglandular stromal cuffing. Stromal cells are uniform, with minimal cytological atypia.
A: phyllodes-like
Back Extra: Adenosarcoma of the vagina
- Clinical: Patients usually present with symptoms of a vaginal mass, including pain, vaginal bleeding, and urinary frequency or incontinence.
- Micro: The morphology includes broad phyllodes-like intraglandular projections, periglandular stromal cuffing, and high-grade nuclear atypia in the mesenchymal component.
- Ancillary: Ancillary studies are not clinically relevant for this neoplasm.
Reference Gallery:
Adenosarcoma. There is a broad phyllodes-like intraglandular projection and periglandular stromal cuffing. Stromal cells are uniform, with minimal cytological atypia.
Adenosarcoma. There is high-grade nuclear atypia of the mesenchymal component and intraglandular leaf-like projections with gland compression.

Q: Microscopically, [...] is a biphasic tumor that exhibits benign glandular elements compressed by a malignant mesenchymal component with high-grade nuclear atypia.
Adenosarcoma. There is high-grade nuclear atypia of the mesenchymal component and intraglandular leaf-like projections with gland compression.
A: Adenosarcoma of the vagina
Back Extra: Adenosarcoma of the vagina
- Clinical: Patients usually present with symptoms of a vaginal mass, including pain, vaginal bleeding, and urinary frequency or incontinence.
- Micro: The morphology includes broad phyllodes-like intraglandular projections, periglandular stromal cuffing, and high-grade nuclear atypia in the mesenchymal component.
- Ancillary: Ancillary studies are not clinically relevant for this neoplasm.
Reference Gallery:
Adenosarcoma. There is a broad phyllodes-like intraglandular projection and periglandular stromal cuffing. Stromal cells are uniform, with minimal cytological atypia.
Adenosarcoma. There is high-grade nuclear atypia of the mesenchymal component and intraglandular leaf-like projections with gland compression.

Q: In Mucinous Carcinoma, Gastric Type, of the Vagina, the tumor typically exhibits morphologic features of [...] differentiation, forming irregularly shaped glands lined by cells with prominent cell membranes and abundant clear/pale eosinophilic cytoplasm.
Vaginal gastric-type adenocarcinoma. The tumour shows irregularly shaped glands lined by cells with prominent cell membranes and abundant clear/pale eosinophilic cytoplasm.
A: gastric
Back Extra: Mucinous Carcinoma, Gastric Type, of the Vagina
- Clinical: Mucinous carcinoma, gastric type, of the vagina primarily affects women aged 41–69 years, presenting with a vaginal mass, discharge, or urinary symptoms.
- Micro: Histologically, the tumor exhibits irregularly shaped glands with clear/pale eosinophilic cytoplasm and prominent cell membranes, often showing gastric differentiation.
- Ancillary: Immunohistochemistry typically shows positivity for MUC6, HIK1083, CDX2, CK7, CEA, CA19-9, and CA125, while hormone receptors and p16 are usually negative.
Reference Gallery:
Vaginal gastric-type adenocarcinoma. The tumour shows irregularly shaped glands lined by cells with prominent cell membranes and abundant clear/pale eosinophilic cytoplasm.

Q: A vaginal biopsy from a 56-year-old woman shows malignant glands with intracytoplasmic mucin and goblet cells. The tumor expresses CDX2 and CK20 but lacks ER. This profile is diagnostic of [...].
Mucinous carcinoma of the vagina, intestinal type. Malignant intestinal-type glands displaying focal goblet cells.
A: Mucinous Carcinoma, Intestinal Type, of the Vagina
Back Extra: Mucinous Carcinoma, Intestinal Type, of the Vagina
- Clinical: Mucinous carcinoma, intestinal type, of the vagina typically presents in older women (median age 56 years) with vaginal bleeding or a mass.
- Micro: Histologically, the tumor shows features of intestinal adenocarcinoma, including intracytoplasmic mucin and goblet cells, and may sometimes have prominent neuroendocrine cells.
- Ancillary: Immunohistochemistry shows expression of CDX2 and CK20, with negativity for ER and variable CK7 staining.
Reference Gallery:
Mucinous carcinoma of the vagina, intestinal type. Malignant intestinal-type glands displaying focal goblet cells.

Q: The defining histologic hallmark of Mucinous Carcinoma, Intestinal Type, of the Vagina is the presence of malignant glands containing intracytoplasmic mucin and distinctive [...].
Mucinous carcinoma of the vagina, intestinal type. Malignant intestinal-type glands displaying focal goblet cells.
A: goblet cells
Back Extra: Mucinous Carcinoma, Intestinal Type, of the Vagina
- Clinical: Mucinous carcinoma, intestinal type, of the vagina typically presents in older women (median age 56 years) with vaginal bleeding or a mass.
- Micro: Histologically, the tumor shows features of intestinal adenocarcinoma, including intracytoplasmic mucin and goblet cells, and may sometimes have prominent neuroendocrine cells.
- Ancillary: Immunohistochemistry shows expression of CDX2 and CK20, with negativity for ER and variable CK7 staining.
Reference Gallery:
Mucinous carcinoma of the vagina, intestinal type. Malignant intestinal-type glands displaying focal goblet cells.

Q: Microscopic evaluation of a vaginal mass showing glandular arrangements of tumor cells with abundant clear cytoplasm and prominent stromal hyalinization is characteristic of [...].
Clear cell carcinoma. Clear cell carcinoma composed of glandular arrangements of tumour cells with abundant clear cytoplasm and stromal hyalinization.
A: Clear Cell Carcinoma of the Vagina
Back Extra: Clear Cell Carcinoma of the Vagina
- Clinical: Clear Cell Carcinoma of the Vagina often presents with vaginal bleeding or discharge, particularly in older women.
- Micro: Histological features include tubulocystic, papillary, and solid arrangements of cells with clear cytoplasm, often with stromal hyalinization and hobnail cells.
- Ancillary: Vaginal smears are effective for early detection, and specific vaginal sampling is crucial.
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Clear cell carcinoma. Clear cell carcinoma composed of glandular arrangements of tumour cells with abundant clear cytoplasm and stromal hyalinization.

Q: Histologically, Clear Cell Carcinoma of the Vagina frequently features tumor cells with abundant clear cytoplasm, prominent stromal hyalinization, and characteristic [...] cells protruding into glandular or cystic spaces.
Clear cell carcinoma. Clear cell carcinoma composed of glandular arrangements of tumour cells with abundant clear cytoplasm and stromal hyalinization.
A: hobnail
Back Extra: Clear Cell Carcinoma of the Vagina
- Clinical: Clear Cell Carcinoma of the Vagina often presents with vaginal bleeding or discharge, particularly in older women.
- Micro: Histological features include tubulocystic, papillary, and solid arrangements of cells with clear cytoplasm, often with stromal hyalinization and hobnail cells.
- Ancillary: Vaginal smears are effective for early detection, and specific vaginal sampling is crucial.
Reference Gallery:
Clear cell carcinoma. Clear cell carcinoma composed of glandular arrangements of tumour cells with abundant clear cytoplasm and stromal hyalinization.

Q: To establish a primary diagnosis of Squamous Cell Carcinoma, HPV-associated, of the Vagina, an essential diagnostic criterion is the absence of a previous (≤ 5 years) or concurrent squamous cell carcinoma of the [...].
Squamous cell carcinoma of the vagina. Gross section of a hysterectomy specimen with colpectomy containing a tumour, 6.5 cm in the largest dimension, growing in the posterior wall of the vagina without uterine cervical involvement.
A: cervix or vulva
Back Extra: Squamous Cell Carcinoma, HPV-associated, of the Vagina
- Clinical: Most cases affect patients in their seventh to ninth decade of life. Signs and symptoms include vaginal bleeding/discharge, postcoital bleeding, urinary symptoms, pelvic pain, and a foreign body sensation within the vagi…
- Micro: Vaginal SCC displays patterns similar to those of cervical SCC, namely, keratinizing, non-keratinizing, warty, basaloid, and papillary patterns. Tumours with mixtures of patterns are common and morphology is not specific…
- Cyto: See section Squamous cell carcinoma, HPV-associated, of the uterine cervix.
- Ancillary: Essential: no previous (≤ 5 years) or concomitant SCC of cervix or vulva; infiltrating, angulated, irregularly sized and shaped nests, anastomosing cords, and solid sheets; nuclear pleomorphism and increased mitotic coun…
Reference Gallery:
Squamous cell carcinoma of the vagina. Gross section of a hysterectomy specimen with colpectomy containing a tumour, 6.5 cm in the largest dimension, growing in the posterior wall of the vagina without uterine cervical involvement.
Poorly differentiated squamous cell carcinoma of the vagina. HPV-associated squamous cell carcinoma located in the upper and middle vagina with deep invasion of the posterior wall.
Vagina cancer map. Estimated age-standardized incidence rates (ASRs; World), per 100,000 person-years, of vagina cancer in 2018.

Q: Grossly, Squamous Cell Carcinoma, HPV-associated, of the Vagina typically presents as a deeply invasive tumor that frequently arises in the upper and middle thirds of the vagina, with a predilection for the [...].
Squamous cell carcinoma of the vagina. Gross section of a hysterectomy specimen with colpectomy containing a tumour, 6.5 cm in the largest dimension, growing in the posterior wall of the vagina without uterine cervical involvement.
Poorly differentiated squamous cell carcinoma of the vagina. HPV-associated squamous cell carcinoma located in the upper and middle vagina with deep invasion of the posterior wall.
A: posterior wall
Back Extra: Squamous Cell Carcinoma, HPV-associated, of the Vagina
- Clinical: Most cases affect patients in their seventh to ninth decade of life. Signs and symptoms include vaginal bleeding/discharge, postcoital bleeding, urinary symptoms, pelvic pain, and a foreign body sensation within the vagi…
- Micro: Vaginal SCC displays patterns similar to those of cervical SCC, namely, keratinizing, non-keratinizing, warty, basaloid, and papillary patterns. Tumours with mixtures of patterns are common and morphology is not specific…
- Cyto: See section Squamous cell carcinoma, HPV-associated, of the uterine cervix.
- Ancillary: Essential: no previous (≤ 5 years) or concomitant SCC of cervix or vulva; infiltrating, angulated, irregularly sized and shaped nests, anastomosing cords, and solid sheets; nuclear pleomorphism and increased mitotic coun…
Reference Gallery:
Squamous cell carcinoma of the vagina. Gross section of a hysterectomy specimen with colpectomy containing a tumour, 6.5 cm in the largest dimension, growing in the posterior wall of the vagina without uterine cervical involvement.
Poorly differentiated squamous cell carcinoma of the vagina. HPV-associated squamous cell carcinoma located in the upper and middle vagina with deep invasion of the posterior wall.
Vagina cancer map. Estimated age-standardized incidence rates (ASRs; World), per 100,000 person-years, of vagina cancer in 2018.

Q: Histologic evaluation of Squamous Cell Carcinoma, HPV-independent, of the Vagina classically demonstrates infiltrating, angulated nests of malignant cells often containing central [...].
Squamous cell carcinoma of the vagina, HPV-independent. Medium-power view of infiltrating, angulated, irregularly sized and shaped nests of malignant squamous cell carcinoma with keratin pearls.
A: keratin pearls
Back Extra: Squamous Cell Carcinoma, HPV-independent, of the Vagina
- Clinical: Squamous cell carcinoma, HPV-independent, of the vagina constitutes 1–2% of all female genital tract malignancies and is most common in postmenopausal women with a median age of 73 years at diagnosis.
- Micro: The histopathology shows infiltrating, angulated, irregularly sized and shaped nests of malignant squamous cells with keratin pearls and a desmoplastic or inflammatory stroma.
- Ancillary: Essential and desirable diagnostic criteria include no previous (≤ 5 years) or concomitant SCC of cervix or vulva, infiltrating nests, nuclear pleomorphism, and negative p16 immunostaining, with molecular testing for HPV advisable.
Reference Gallery:
Squamous cell carcinoma of the vagina, HPV-independent. Lower-power view of an ulcerated moderately differentiated squamous cell carcinoma.
Squamous cell carcinoma of the vagina, HPV-independent. Medium-power view of infiltrating, angulated, irregularly sized and shaped nests of malignant squamous cell carcinoma with keratin pearls.
Squamous cell carcinoma of the vagina, HPV-independent. High-power view. Infiltrative border with desmoplastic and inflammatory stroma. Malignant squamous cell with nuclear pleomorphism and mitoses.

Q: At high power, the infiltrative border of Squamous Cell Carcinoma, HPV-independent, of the Vagina frequently induces a reactive [...] or inflammatory stroma surrounding the pleomorphic malignant cells.
Squamous cell carcinoma of the vagina, HPV-independent. High-power view. Infiltrative border with desmoplastic and inflammatory stroma. Malignant squamous cell with nuclear pleomorphism and mitoses.
A: desmoplastic
Back Extra: Squamous Cell Carcinoma, HPV-independent, of the Vagina
- Clinical: Squamous cell carcinoma, HPV-independent, of the vagina constitutes 1–2% of all female genital tract malignancies and is most common in postmenopausal women with a median age of 73 years at diagnosis.
- Micro: The histopathology shows infiltrating, angulated, irregularly sized and shaped nests of malignant squamous cells with keratin pearls and a desmoplastic or inflammatory stroma.
- Ancillary: Essential and desirable diagnostic criteria include no previous (≤ 5 years) or concomitant SCC of cervix or vulva, infiltrating nests, nuclear pleomorphism, and negative p16 immunostaining, with molecular testing for HPV advisable.
Reference Gallery:
Squamous cell carcinoma of the vagina, HPV-independent. Lower-power view of an ulcerated moderately differentiated squamous cell carcinoma.
Squamous cell carcinoma of the vagina, HPV-independent. Medium-power view of infiltrating, angulated, irregularly sized and shaped nests of malignant squamous cell carcinoma with keratin pearls.
Squamous cell carcinoma of the vagina, HPV-independent. High-power view. Infiltrative border with desmoplastic and inflammatory stroma. Malignant squamous cell with nuclear pleomorphism and mitoses.

Q: Histologically, a genital Rhabdomyoma features a haphazard arrangement of spindle and strap-shaped cells with abundant eosinophilic cytoplasm and characteristic [...].
Genital rhabdomyoma. Haphazard arrangement of spindle and strap-shaped cells with cross-striations within subepithelial fibrovascular stroma.
A: cross-striations
Back Extra: Rhabdomyoma
- Clinical: Rhabdomyomas are often asymptomatic but can cause dyspareunia, bleeding, or urinary tract compression. Common in women aged 30–55 years.
- Micro: Characterized by subepithelial spindle, ovoid, or strap-shaped cells with cross-striations and abundant eosinophilic cytoplasm. No mitoses or nuclear pleomorphism.
- Ancillary: Immunohistochemical analysis shows positivity for desmin, myogenin, and MYOD1. No somatic changes involving hedgehog pathway genes.
Reference Gallery:
Genital rhabdomyoma. Haphazard arrangement of spindle and strap-shaped cells with cross-striations within subepithelial fibrovascular stroma.

Q: A middle-aged woman presents with dyspareunia. Biopsy reveals a subepithelial proliferation of strap-shaped cells with cross-striations (shown in image) that are positive for desmin and MYOD1. This benign mesenchymal tumor is a genital [...].
Genital rhabdomyoma. Haphazard arrangement of spindle and strap-shaped cells with cross-striations within subepithelial fibrovascular stroma.
A: Rhabdomyoma
Back Extra: Rhabdomyoma
- Clinical: Rhabdomyomas are often asymptomatic but can cause dyspareunia, bleeding, or urinary tract compression. Common in women aged 30–55 years.
- Micro: Characterized by subepithelial spindle, ovoid, or strap-shaped cells with cross-striations and abundant eosinophilic cytoplasm. No mitoses or nuclear pleomorphism.
- Ancillary: Immunohistochemical analysis shows positivity for desmin, myogenin, and MYOD1. No somatic changes involving hedgehog pathway genes.
Reference Gallery:
Genital rhabdomyoma. Haphazard arrangement of spindle and strap-shaped cells with cross-striations within subepithelial fibrovascular stroma.

Q: Superficial Myofibroblastoma characteristically presents as a well-defined, unencapsulated spindle cell lesion separated from the overlying epithelium by a [...].
Superficial myofibroblastoma. Well-defined, unencapsulated lesion separated from the surface by a grenz zone.
A: grenz zone
Back Extra: Superficial Myofibroblastoma
- Clinical: Patients may present with a polyp or cystic mass; lesions may be incidental and occur over a wide age range (23–80 years).
- Micro: Characterized by a well-circumscribed but unencapsulated lesion with a grenz zone, a patternless architecture, and finely collagenous stroma.
- Ancillary: Spindle cells are positive for vimentin, CD34, ER, PR, and desmin, but negative for S100.
Reference Gallery:
Superficial myofibroblastoma. Well-defined, unencapsulated lesion separated from the surface by a grenz zone.
Patternless arrangement of spindle cells with fine collagenous stroma. Superficial myofibroblastoma

Q: Superficial Myofibroblastoma features a microscopic appearance consisting of a [...] arrangement of spindle cells set within a finely collagenous stroma.
Patternless arrangement of spindle cells with fine collagenous stroma. Superficial myofibroblastoma
A: patternless
Back Extra: Superficial Myofibroblastoma
- Clinical: Patients may present with a polyp or cystic mass; lesions may be incidental and occur over a wide age range (23–80 years).
- Micro: Characterized by a well-circumscribed but unencapsulated lesion with a grenz zone, a patternless architecture, and finely collagenous stroma.
- Ancillary: Spindle cells are positive for vimentin, CD34, ER, PR, and desmin, but negative for S100.
Reference Gallery:
Superficial myofibroblastoma. Well-defined, unencapsulated lesion separated from the surface by a grenz zone.
Patternless arrangement of spindle cells with fine collagenous stroma. Superficial myofibroblastoma

Q: In Condyloma acuminatum, the characteristic viral cytopathic effect seen in superficial keratinocytes is [...] atypia.
Condyloma acuminatum. Presence of koilocytic atypia in the superficial keratinocytes.
A: koilocytic
Back Extra: Condyloma acuminatum
- Clinical: Genital warts are usually small (1–5 mm) but can grow into large masses, often asymptomatic but may cause itching, redness, or discomfort.
- Micro: Key features include acanthosis, papillomatosis, parakeratosis, hypergranulosis, and hyperkeratosis, with variable koilocytic change.
- Ancillary: HPV, usually low-risk types (HPV6 and HPV11), can be identified by PCR or in situ hybridization; p16 immunostaining shows irregular, patchy staining.
Reference Gallery:
Condyloma acuminatum. Verrucous lesion with papillomatosis, acanthosis, and hyperkeratosis.
Condyloma acuminatum. Presence of koilocytic atypia in the superficial keratinocytes.

Q: The diagnosis of [...] is characterized by a verrucous lesion exhibiting papillomatosis, acanthosis, hyperkeratosis, and superficial viral cytopathic changes.
Condyloma acuminatum. Verrucous lesion with papillomatosis, acanthosis, and hyperkeratosis.
Condyloma acuminatum. Presence of koilocytic atypia in the superficial keratinocytes.
A: Condyloma acuminatum
Back Extra: Condyloma acuminatum
- Clinical: Genital warts are usually small (1–5 mm) but can grow into large masses, often asymptomatic but may cause itching, redness, or discomfort.
- Micro: Key features include acanthosis, papillomatosis, parakeratosis, hypergranulosis, and hyperkeratosis, with variable koilocytic change.
- Ancillary: HPV, usually low-risk types (HPV6 and HPV11), can be identified by PCR or in situ hybridization; p16 immunostaining shows irregular, patchy staining.
Reference Gallery:
Condyloma acuminatum. Verrucous lesion with papillomatosis, acanthosis, and hyperkeratosis.
Condyloma acuminatum. Presence of koilocytic atypia in the superficial keratinocytes.

Q: Microscopically, Fibroadenoma is classically described as a well-circumscribed, [...] epithelial-stromal neoplasm.
Fibroadenoma. A biphasic epithelial-stromal neoplasm lined by bland epithelium within a relatively uniform, hypocellular stroma composed of spindled or stellate cells without nuclear atypia.
A: biphasic
Back Extra: Fibroadenoma
- Clinical: Vulvar fibroadenomas occur predominantly in women of reproductive age and appear as solitary, firm, subcutaneous nodules that may enlarge during pregnancy.
- Micro: These lesions are well circumscribed, composed of glandular elements lined by bland epithelium within a uniform, hypocellular stroma.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of vulvar fibroadenomas.
Reference Gallery:
Fibroadenoma. A biphasic epithelial-stromal neoplasm lined by bland epithelium within a relatively uniform, hypocellular stroma composed of spindled or stellate cells without nuclear atypia.
Fibroadenoma. Fibroadenoma with prominent myxoid stroma.

Q: To differentiate from other stromal lesions, the background stroma in a typical Fibroadenoma is characteristically uniform and [...], composed of spindled or stellate cells without nuclear atypia.
Fibroadenoma. A biphasic epithelial-stromal neoplasm lined by bland epithelium within a relatively uniform, hypocellular stroma composed of spindled or stellate cells without nuclear atypia.
Fibroadenoma. Fibroadenoma with prominent myxoid stroma.
A: hypocellular
Back Extra: Fibroadenoma
- Clinical: Vulvar fibroadenomas occur predominantly in women of reproductive age and appear as solitary, firm, subcutaneous nodules that may enlarge during pregnancy.
- Micro: These lesions are well circumscribed, composed of glandular elements lined by bland epithelium within a uniform, hypocellular stroma.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of vulvar fibroadenomas.
Reference Gallery:
Fibroadenoma. A biphasic epithelial-stromal neoplasm lined by bland epithelium within a relatively uniform, hypocellular stroma composed of spindled or stellate cells without nuclear atypia.
Fibroadenoma. Fibroadenoma with prominent myxoid stroma.

Q: The characteristic bilayered epithelium of a papillary hidradenoma consists of inner cuboidal to columnar secretory cells and an underlying layer of [...] cells.
Papillary hidradenoma. Complex branching and interconnecting tubules and papillae lined by uniform, cuboidal to columnar secretory cells and underlying myoepithelial cells. Note the area of apocrine change on the lower left.
A: myoepithelial
Back Extra: Papillary Hidradenoma
- Clinical: Commonly affects women in their third or fourth decade, presenting as a solitary, firm mass, sometimes with overlying ulceration and bleeding.
- Micro: Characterized by complex branching and interconnecting tubules and papillae lined by cuboidal to columnar secretory cells and underlying myoepithelial cells.
- Ancillary: Ancillary studies are not clinically relevant for diagnosis.
Reference Gallery:
Papillary hidradenoma. Complex branching and interconnecting tubules and papillae lined by uniform, cuboidal to columnar secretory cells and underlying myoepithelial cells. Note the area of apocrine change on the lower left.

Q: The complex branching tubules and papillae in a papillary hidradenoma are lined by uniform secretory and myoepithelial cells, which frequently display prominent [...] change.
Papillary hidradenoma. Complex branching and interconnecting tubules and papillae lined by uniform, cuboidal to columnar secretory cells and underlying myoepithelial cells. Note the area of apocrine change on the lower left.
A: apocrine
Back Extra: Papillary Hidradenoma
- Clinical: Commonly affects women in their third or fourth decade, presenting as a solitary, firm mass, sometimes with overlying ulceration and bleeding.
- Micro: Characterized by complex branching and interconnecting tubules and papillae lined by cuboidal to columnar secretory cells and underlying myoepithelial cells.
- Ancillary: Ancillary studies are not clinically relevant for diagnosis.
Reference Gallery:
Papillary hidradenoma. Complex branching and interconnecting tubules and papillae lined by uniform, cuboidal to columnar secretory cells and underlying myoepithelial cells. Note the area of apocrine change on the lower left.

Q: Histologically, a nodular or lobular proliferation of morphologically bland mucinous acini with preservation of normal ductal arrangement in the vulvar region is characteristic of [...].
Bartholin gland hyperplasia. Proliferation of morphologically bland mucinous acini surrounding ducts.
A: Bartholin gland hyperplasia, adenoma, and adenomyoma
Q: Bartholin gland hyperplasia, adenoma, and adenomyoma
- Clinical: Presentation is usually with a [...] in patients around the age of 35 years (range: 19–56 years).
- Micro: Hyperplasia is characterized by a [...] of morphologically bland mucinous acini with preservation of the normal acinar and ductal arrangement.
- Ancillary: [...] for diagnosis and management.
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Bartholin gland hyperplasia. Proliferation of morphologically bland mucinous acini surrounding ducts.
A: painless swelling; nodular/lobular proliferation; Not clinically relevant

Q: In Bartholin gland hyperplasia, adenoma, and adenomyoma, the characteristic microscopic finding is a nodular or lobular proliferation of morphologically bland [...] surrounding the ducts.
Bartholin gland hyperplasia. Proliferation of morphologically bland mucinous acini surrounding ducts.
A: mucinous acini
Q: Bartholin gland hyperplasia, adenoma, and adenomyoma
- Clinical: Presentation is usually with a [...] in patients around the age of 35 years (range: 19–56 years).
- Micro: Hyperplasia is characterized by a [...] of morphologically bland mucinous acini with preservation of the normal acinar and ductal arrangement.
- Ancillary: [...] for diagnosis and management.
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Bartholin gland hyperplasia. Proliferation of morphologically bland mucinous acini surrounding ducts.
A: painless swelling; nodular/lobular proliferation; Not clinically relevant

Q: Chondroid Syringoma is histologically characterized by a well-circumscribed dermal-based lesion featuring epithelial and myoepithelial cells that form tubules or trabeculae embedded within a characteristic [...] stroma.
Chondroid syringoma. A well-circumscribed lesion with epithelial, myoepithelial, and stromal elements. The epithelial cells form tubules or trabeculae with associated myoepithelial cells within fibromyxoid stroma.
A: fibromyxoid
Back Extra: Chondroid Syringoma
- Clinical: Chondroid syringomas typically present in postmenopausal women as a slow-growing, solitary, painless nodule on the vulva, including the Bartholin gland, vestibular glands, or anogenital mammary-like glands.
- Micro: Histologically, chondroid syringomas are well-circumscribed dermal-based lesions with a mix of epithelial, myoepithelial, and stromal elements, leading to the formation of tubules or trabeculae within a fibromyxoid stroma.
- Ancillary: Ancillary studies for chondroid syringoma are not clinically relevant, and the diagnosis is primarily based on histological features.
Reference Gallery:
Chondroid syringoma. A well-circumscribed lesion with epithelial, myoepithelial, and stromal elements. The epithelial cells form tubules or trabeculae with associated myoepithelial cells within fibromyxoid stroma.

Q: Chondroid Syringoma microscopically exhibits a well-circumscribed dermal lesion containing a characteristic admixture of [...] cellular elements forming tubules within a stromal matrix.
Chondroid syringoma. A well-circumscribed lesion with epithelial, myoepithelial, and stromal elements. The epithelial cells form tubules or trabeculae with associated myoepithelial cells within fibromyxoid stroma.
A: epithelial and myoepithelial
Back Extra: Chondroid Syringoma
- Clinical: Chondroid syringomas typically present in postmenopausal women as a slow-growing, solitary, painless nodule on the vulva, including the Bartholin gland, vestibular glands, or anogenital mammary-like glands.
- Micro: Histologically, chondroid syringomas are well-circumscribed dermal-based lesions with a mix of epithelial, myoepithelial, and stromal elements, leading to the formation of tubules or trabeculae within a fibromyxoid stroma.
- Ancillary: Ancillary studies for chondroid syringoma are not clinically relevant, and the diagnosis is primarily based on histological features.
Reference Gallery:
Chondroid syringoma. A well-circumscribed lesion with epithelial, myoepithelial, and stromal elements. The epithelial cells form tubules or trabeculae with associated myoepithelial cells within fibromyxoid stroma.

Q: A classic histologic finding in Seborrhoeic Keratosis is an acanthotic epidermis with benign basaloid cells and characteristic keratin-filled [...].
Seborrhoeic keratosis. An acanthotic lesion with proliferation of basaloid cells, showing keratin-filled horn cysts.
Seborrhoeic keratosis. Keratin-filled cysts and absence of atypia.
A: pseudohorn cysts
Back Extra: Seborrhoeic Keratosis
- Clinical: Seborrhoeic keratosis presents as asymptomatic, raised, maculopapular, nodular, or plaque-like lesions, often pigmented.
- Micro: Histologically, the lesion shows an acanthotic epidermis with variable papillomatosis, hyperkeratosis, and pseudohorn cysts, but no significant nuclear atypia.
- Ancillary: HPV positivity by in situ hybridization or PCR can help differentiate seborrhoeic keratosis from condyloma acuminatum.
Reference Gallery:
Seborrhoeic keratosis. An acanthotic lesion with proliferation of basaloid cells, showing keratin-filled horn cysts.
Seborrhoeic keratosis. Keratin-filled cysts and absence of atypia.

Q: In Seborrhoeic Keratosis, the acanthotic epidermal lesion typically lacks significant nuclear atypia and is predominantly driven by a benign proliferation of [...] cells.
Seborrhoeic keratosis. An acanthotic lesion with proliferation of basaloid cells, showing keratin-filled horn cysts.
A: basaloid
Back Extra: Seborrhoeic Keratosis
- Clinical: Seborrhoeic keratosis presents as asymptomatic, raised, maculopapular, nodular, or plaque-like lesions, often pigmented.
- Micro: Histologically, the lesion shows an acanthotic epidermis with variable papillomatosis, hyperkeratosis, and pseudohorn cysts, but no significant nuclear atypia.
- Ancillary: HPV positivity by in situ hybridization or PCR can help differentiate seborrhoeic keratosis from condyloma acuminatum.
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Seborrhoeic keratosis. An acanthotic lesion with proliferation of basaloid cells, showing keratin-filled horn cysts.
Seborrhoeic keratosis. Keratin-filled cysts and absence of atypia.

Q: Histologically, Adenocarcinoma of Intestinal Type resembles colorectal adenocarcinoma and is characterized by malignant glands containing intracytoplasmic mucin and [...].
Adenocarcinoma of intestinal type. The tumour is composed of malignant glands within an inflamed stroma.
A: goblet cells
Back Extra: Adenocarcinoma of Intestinal Type
- Clinical: Most patients present with a mass or bleeding from the posterior vestibule/fourchette. These are extremely rare vulvar neoplasms.
- Micro: The morphology is similar to colorectal adenocarcinoma, with intracytoplasmic mucin and goblet cells. They may also show anaplastic and spindle cell components.
- Ancillary: Immunohistochemical markers such as CK20 and CDX2 are typically positive in these tumours.
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Adenocarcinoma of intestinal type. The tumour is composed of malignant glands within an inflamed stroma.
Adenocarcinoma of intestinal type. This shows diffuse nuclear immunoreactivity with CDX2.

Q: To confirm the diagnosis of Adenocarcinoma of Intestinal Type, immunohistochemistry is often utilized, which typically shows diffuse nuclear positivity for [...] alongside CK20.
Adenocarcinoma of intestinal type. This shows diffuse nuclear immunoreactivity with CDX2.
A: CDX2
Back Extra: Adenocarcinoma of Intestinal Type
- Clinical: Most patients present with a mass or bleeding from the posterior vestibule/fourchette. These are extremely rare vulvar neoplasms.
- Micro: The morphology is similar to colorectal adenocarcinoma, with intracytoplasmic mucin and goblet cells. They may also show anaplastic and spindle cell components.
- Ancillary: Immunohistochemical markers such as CK20 and CDX2 are typically positive in these tumours.
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Adenocarcinoma of intestinal type. The tumour is composed of malignant glands within an inflamed stroma.
Adenocarcinoma of intestinal type. This shows diffuse nuclear immunoreactivity with CDX2.

Q: A solitary vulvar tumor showing ductal differentiation identical to breast carcinoma of invasive ductal type is characteristic of [...].
Adenocarcinoma of mammary gland type. The tumour shows ductal differentiation, similar to breast carcinoma of invasive ductal type.
A: Adenocarcinoma of mammary gland type
Back Extra: Adenocarcinoma of mammary gland type
- Clinical: Most patients are postmenopausal and present with a solitary vulvar mass, typically occurring in multiparous women aged ≥ 60 years.
- Micro: The most common type is adenocarcinoma identical to mammary invasive ductal carcinoma, with common expression of ER, PR, and ERBB2 (HER2).
- Ancillary: Mutations in the genes of the PI3K/AKT cascade have been found in a few studied cases, and secretory carcinoma harbours ETV6-NTRK3 fusion.
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Adenocarcinoma of mammary gland type. The tumour shows ductal differentiation, similar to breast carcinoma of invasive ductal type.

Q: Microscopically, the most common morphologic pattern of Adenocarcinoma of mammary gland type is identical to mammary invasive [...] carcinoma.
Adenocarcinoma of mammary gland type. The tumour shows ductal differentiation, similar to breast carcinoma of invasive ductal type.
A: ductal
Back Extra: Adenocarcinoma of mammary gland type
- Clinical: Most patients are postmenopausal and present with a solitary vulvar mass, typically occurring in multiparous women aged ≥ 60 years.
- Micro: The most common type is adenocarcinoma identical to mammary invasive ductal carcinoma, with common expression of ER, PR, and ERBB2 (HER2).
- Ancillary: Mutations in the genes of the PI3K/AKT cascade have been found in a few studied cases, and secretory carcinoma harbours ETV6-NTRK3 fusion.
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Adenocarcinoma of mammary gland type. The tumour shows ductal differentiation, similar to breast carcinoma of invasive ductal type.

Q: The adenoid cystic carcinoma subtype of Bartholin Gland Carcinoma is morphologically characterized by a [...] architecture, consisting of uniform cells surrounding round spaces filled with mucoid material.
Adenoid cystic carcinoma of Bartholin gland. The tumour is composed of cribriform arrangements of uniform cells with round spaces containing mucoid material.
A: cribriform
Back Extra: Bartholin Gland Carcinoma
- Clinical: Bartholin gland carcinomas typically occur in middle-aged to elderly women, presenting as painless masses in the Bartholin gland area, which can be mistaken for cysts or abscesses.
- Micro: Squamous cell carcinoma is the most common morphological type, followed by adenocarcinoma. Adenoid cystic carcinoma is a rare subtype characterized by cribriform arrangements of uniform cells with round spaces containing mucoid material.
- Ancillary: While ancillary studies are not clinically relevant, the presence of a transition zone between benign Bartholin gland tissue and the tumor helps in diagnosis.
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Adenoid cystic carcinoma of Bartholin gland. The tumour is composed of cribriform arrangements of uniform cells with round spaces containing mucoid material.

Q: A rare variant of Bartholin Gland Carcinoma is the [...] carcinoma subtype, which typically presents as a tumor with a cribriform arrangement of uniform cells surrounding round, mucoid-filled spaces.
Adenoid cystic carcinoma of Bartholin gland. The tumour is composed of cribriform arrangements of uniform cells with round spaces containing mucoid material.
A: adenoid cystic
Back Extra: Bartholin Gland Carcinoma
- Clinical: Bartholin gland carcinomas typically occur in middle-aged to elderly women, presenting as painless masses in the Bartholin gland area, which can be mistaken for cysts or abscesses.
- Micro: Squamous cell carcinoma is the most common morphological type, followed by adenocarcinoma. Adenoid cystic carcinoma is a rare subtype characterized by cribriform arrangements of uniform cells with round spaces containing mucoid material.
- Ancillary: While ancillary studies are not clinically relevant, the presence of a transition zone between benign Bartholin gland tissue and the tumor helps in diagnosis.
Reference Gallery:
Adenoid cystic carcinoma of Bartholin gland. The tumour is composed of cribriform arrangements of uniform cells with round spaces containing mucoid material.

Q: Histologically, Vulvar Paget Disease is characterized by large, atypical cells with pale, vacuolated cytoplasm, known as [...], which are located predominantly in the basal layer with upward extension into the superficial epidermis.
Vulvar Paget disease. Clusters of atypical vacuolated cells are present in the basal layer, with individual cells and smaller clusters extending upwards into the superficial epidermis.
A: Paget cells
Back Extra: Vulvar Paget Disease
- Clinical: Patients with Vulvar Paget Disease often present with a pruritic, erythematous, eczematous lesion that mimics a vulvar dermatosis or high-grade squamous intraepithelial lesion (VIN 3).
- Micro: Large round Paget cells with pale cytoplasm and a large nucleus, often with a prominent nucleolus, are present within the epidermis, predominantly in the basal layers, with occasional extension into the superficial epidermis.
- Ancillary: Immunohistochemistry (IHC) is positive for CK7, EMA, CAM5.2, CEA, and GATA3, and negative for melanoma markers and HPV.
Reference Gallery:
Vulvar Paget disease. Diffuse nuclear staining for ER in Paget cells.
Vulvar Paget disease. Clusters of atypical vacuolated cells are present in the basal layer, with individual cells and smaller clusters extending upwards into the superficial epidermis.
Vulvar Paget disease. The cells of vulvar Paget disease strongly express CK7.

Q: In Vulvar Paget Disease, immunohistochemistry characteristically demonstrates strong expression of [...], which alongside other markers like EMA and CEA helps differentiate it from squamous intraepithelial lesions and melanoma.
Vulvar Paget disease. The cells of vulvar Paget disease strongly express CK7.
A: CK7
Back Extra: Vulvar Paget Disease
- Clinical: Patients with Vulvar Paget Disease often present with a pruritic, erythematous, eczematous lesion that mimics a vulvar dermatosis or high-grade squamous intraepithelial lesion (VIN 3).
- Micro: Large round Paget cells with pale cytoplasm and a large nucleus, often with a prominent nucleolus, are present within the epidermis, predominantly in the basal layers, with occasional extension into the superficial epidermis.
- Ancillary: Immunohistochemistry (IHC) is positive for CK7, EMA, CAM5.2, CEA, and GATA3, and negative for melanoma markers and HPV.
Reference Gallery:
Vulvar Paget disease. Diffuse nuclear staining for ER in Paget cells.
Vulvar Paget disease. Clusters of atypical vacuolated cells are present in the basal layer, with individual cells and smaller clusters extending upwards into the superficial epidermis.
Vulvar Paget disease. The cells of vulvar Paget disease strongly express CK7.

Q: Microscopically, the most common architectural pattern seen in a Germ Cell Tumor of the Vulva (specifically the yolk sac tumor subtype, as shown) is the [...] pattern.
Yolk sac tumour. Reticular pattern of yolk sac tumour.
A: reticular
Back Extra: Germ Cell Tumour of the Vulva
- Clinical: Patients are mostly young women aged < 30 years, presenting with a progressively growing vulvar mass, most commonly localized to the right labium majus.
- Micro: The tumours show a variety of architectural patterns, with reticular being the most common. The tumour cells are large, with hyperchromatic, irregular nuclei, prominent nucleoli, and clear cytoplasm positive for AFP, glypican-3 (GPC3), and SALL4.
- Ancillary: Essential for diagnosis are compatible architectural patterns, cellular detail, and immunohistochemistry.
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Yolk sac tumour. Reticular pattern of yolk sac tumour.

Q: The provided image displays a characteristic reticular architectural pattern composed of large cells with hyperchromatic nuclei and clear cytoplasm, representing the most common histologic presentation of a [...].
Yolk sac tumour. Reticular pattern of yolk sac tumour.
A: Germ Cell Tumor of the Vulva
Back Extra: Germ Cell Tumour of the Vulva
- Clinical: Patients are mostly young women aged < 30 years, presenting with a progressively growing vulvar mass, most commonly localized to the right labium majus.
- Micro: The tumours show a variety of architectural patterns, with reticular being the most common. The tumour cells are large, with hyperchromatic, irregular nuclei, prominent nucleoli, and clear cytoplasm positive for AFP, glypican-3 (GPC3), and SALL4.
- Ancillary: Essential for diagnosis are compatible architectural patterns, cellular detail, and immunohistochemistry.
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Yolk sac tumour. Reticular pattern of yolk sac tumour.

Q: Histologically, Phyllodes Tumor is characterized by bland glandular elements lined by mammary-like epithelium and a prominent [...] stromal growth.
Phyllodes tumour. Bland glandular elements lined by mammary-like epithelium, with a prominent leaf-like stromal growth protruding into the glandular lumina.
A: leaf-like
Back Extra: Phyllodes Tumor
- Clinical: Phyllodes tumors are very uncommon vulvar neoplasms that typically present as a rapidly growing vulvar mass in the labium majus, affecting patients with an average age of 39 years.
- Micro: Phyllodes tumors are characterized by bland glandular elements lined by mammary-like epithelium and a prominent leaf-like stromal growth. They show regional variability in stromal cellularity, with areas of hypercellularity and increased mitotic activity.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of phyllodes tumors.
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Phyllodes tumour. Bland glandular elements lined by mammary-like epithelium, with a prominent leaf-like stromal growth protruding into the glandular lumina.
Phyllodes tumour. Variable stromal cellularity, with band-like areas of hypercellularity and increased mitotic activity around the epithelial components.

Q: The stroma of a Phyllodes Tumor characteristically shows regional variability, often displaying band-like areas of [...] and increased mitotic activity concentrated around the epithelial components.
Phyllodes tumour. Variable stromal cellularity, with band-like areas of hypercellularity and increased mitotic activity around the epithelial components.
A: hypercellularity
Back Extra: Phyllodes Tumor
- Clinical: Phyllodes tumors are very uncommon vulvar neoplasms that typically present as a rapidly growing vulvar mass in the labium majus, affecting patients with an average age of 39 years.
- Micro: Phyllodes tumors are characterized by bland glandular elements lined by mammary-like epithelium and a prominent leaf-like stromal growth. They show regional variability in stromal cellularity, with areas of hypercellularity and increased mitotic activity.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of phyllodes tumors.
Reference Gallery:
Phyllodes tumour. Bland glandular elements lined by mammary-like epithelium, with a prominent leaf-like stromal growth protruding into the glandular lumina.
Phyllodes tumour. Variable stromal cellularity, with band-like areas of hypercellularity and increased mitotic activity around the epithelial components.

Q: Microscopically, Squamous Cell Carcinoma, HPV-associated, of the Vulva typically presents as a moderately to poorly differentiated tumor with characteristic warty or [...] patterns.
HPV-associated vulvar squamous cell carcinoma, basaloid type. Legend text not found
HPV-associated vulvar squamous cell carcinoma. HPV-associated vulvar squamous cell carcinoma with mixed basaloid and keratinizing features. The tumour consists of irregularly shaped nests composed of poorly organized, immature, undifferentiated cells that resemble high-grade squamous intraepithelial lesion, showing frequent mitotic figures. There are foci of keratinization. Abundant melanophages are seen on the left.
A: basaloid
Back Extra: Squamous Cell Carcinoma, HPV-associated, of the Vulva
- Clinical: Peak incidence is in the seventh decade of life, but can occur in young people. Symptoms include asymptomatic mass, ulcer, pruritus, burning, pain, or bleeding.
- Micro: Tumour is composed of infiltrating islands of malignant squamous cells. HPV-associated SCC is typically moderately to poorly differentiated, with basaloid and warty patterns.
- Ancillary: Essential criteria include p16 block-type immunoreactivity and/or positive molecular testing for HPV. Adjacent high-grade squamous intraepithelial lesion is supportive but not essential.
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HPV-associated vulvar squamous cell carcinoma, basaloid type. Legend text not found
HPV-associated vulvar squamous cell carcinoma. HPV-associated vulvar squamous cell carcinoma with mixed basaloid and keratinizing features. The tumour consists of irregularly shaped nests composed of poorly organized, immature, undifferentiated cells that resemble high-grade squamous intraepithelial lesion, showing frequent mitotic figures. There are foci of keratinization. Abundant melanophages are seen on the left.
HPV-associated vulvar squamous cell carcinoma. The tumoural cells show strong and diffuse, cytoplasmic and nuclear block-type positivity for p16. p16 is typically overexpressed in HPV-associated vulvar squamous cell carcinomas.
Vulva cancer map. Estimated age-standardized incidence rates (ASRs; World), per 100,000 person-years, of vulva cancer in 2018.

Q: An essential immunohistochemical criterion for diagnosing Squamous Cell Carcinoma, HPV-associated, of the Vulva is strong, diffuse [...] immunoreactivity for p16.
HPV-associated vulvar squamous cell carcinoma. The tumoural cells show strong and diffuse, cytoplasmic and nuclear block-type positivity for p16. p16 is typically overexpressed in HPV-associated vulvar squamous cell carcinomas.
A: block-type
Back Extra: Squamous Cell Carcinoma, HPV-associated, of the Vulva
- Clinical: Peak incidence is in the seventh decade of life, but can occur in young people. Symptoms include asymptomatic mass, ulcer, pruritus, burning, pain, or bleeding.
- Micro: Tumour is composed of infiltrating islands of malignant squamous cells. HPV-associated SCC is typically moderately to poorly differentiated, with basaloid and warty patterns.
- Ancillary: Essential criteria include p16 block-type immunoreactivity and/or positive molecular testing for HPV. Adjacent high-grade squamous intraepithelial lesion is supportive but not essential.
Reference Gallery:
HPV-associated vulvar squamous cell carcinoma, basaloid type. Legend text not found
HPV-associated vulvar squamous cell carcinoma. HPV-associated vulvar squamous cell carcinoma with mixed basaloid and keratinizing features. The tumour consists of irregularly shaped nests composed of poorly organized, immature, undifferentiated cells that resemble high-grade squamous intraepithelial lesion, showing frequent mitotic figures. There are foci of keratinization. Abundant melanophages are seen on the left.
HPV-associated vulvar squamous cell carcinoma. The tumoural cells show strong and diffuse, cytoplasmic and nuclear block-type positivity for p16. p16 is typically overexpressed in HPV-associated vulvar squamous cell carcinomas.
Vulva cancer map. Estimated age-standardized incidence rates (ASRs; World), per 100,000 person-years, of vulva cancer in 2018.

Q: A well-differentiated tumor with prominent keratin pearl formation and negative p16 staining is highly characteristic of [...].
Squamous cell carcinoma, HPV-independent. Keratinizing type. Well-differentiated squamous cell carcinoma with prominent keratin pearl formation and individual keratinization. This tumour was p16-negative and showed diffuse and strong nuclear staining for p53.
A: Squamous Cell Carcinoma, HPV-independent
Back Extra: Squamous Cell Carcinoma, HPV-independent
- Clinical: Peak incidence is in the eighth decade of life, often presenting as asymptomatic masses or ulcers with symptoms like pruritus, pain, or bleeding in advanced stages.
- Micro: Typically well-differentiated keratinizing carcinomas with keratin pearl formation; verrucous type shows cohesive or verruciform growth patterns with minimal atypia.
- Ancillary: p16 staining is usually negative, and p53 immunohistochemical staining can show overexpression or wildtype expression.
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Squamous cell carcinoma, HPV-independent. Keratinizing type. Well-differentiated squamous cell carcinoma with prominent keratin pearl formation and individual keratinization. This tumour was p16-negative and showed diffuse and strong nuclear staining for p53.
Squamous cell carcinoma, HPV-independent. Verrucous type.
Squamous cell carcinoma, HPV-independent. p53 immunohistochemical staining shows scattered nuclear positivity in the proliferating keratinocytes, representing wildtype expression.
Squamous cell carcinoma, HPV-independent. p53 immunohistochemistry shows positive staining. Tumoural cells show strong nuclear positivity (overexpression), which is consistent with missense mutation.

Q: The verrucous variant of [...] is characterized by cohesive or verruciform growth patterns with minimal cytologic atypia.
Squamous cell carcinoma, HPV-independent. Verrucous type.
A: Squamous Cell Carcinoma, HPV-independent
Back Extra: Squamous Cell Carcinoma, HPV-independent
- Clinical: Peak incidence is in the eighth decade of life, often presenting as asymptomatic masses or ulcers with symptoms like pruritus, pain, or bleeding in advanced stages.
- Micro: Typically well-differentiated keratinizing carcinomas with keratin pearl formation; verrucous type shows cohesive or verruciform growth patterns with minimal atypia.
- Ancillary: p16 staining is usually negative, and p53 immunohistochemical staining can show overexpression or wildtype expression.
Reference Gallery:
Squamous cell carcinoma, HPV-independent. Keratinizing type. Well-differentiated squamous cell carcinoma with prominent keratin pearl formation and individual keratinization. This tumour was p16-negative and showed diffuse and strong nuclear staining for p53.
Squamous cell carcinoma, HPV-independent. Verrucous type.
Squamous cell carcinoma, HPV-independent. p53 immunohistochemical staining shows scattered nuclear positivity in the proliferating keratinocytes, representing wildtype expression.
Squamous cell carcinoma, HPV-independent. p53 immunohistochemistry shows positive staining. Tumoural cells show strong nuclear positivity (overexpression), which is consistent with missense mutation.

Q: In Squamous Cell Carcinoma, HPV-independent, ancillary testing typically shows negative p16, whereas [...] immunohistochemistry can demonstrate either scattered wildtype staining or diffuse strong overexpression (indicating a missense mutation).
Squamous cell carcinoma, HPV-independent. p53 immunohistochemical staining shows scattered nuclear positivity in the proliferating keratinocytes, representing wildtype expression.
Squamous cell carcinoma, HPV-independent. p53 immunohistochemistry shows positive staining. Tumoural cells show strong nuclear positivity (overexpression), which is consistent with missense mutation.
A: p53
Back Extra: Squamous Cell Carcinoma, HPV-independent
- Clinical: Peak incidence is in the eighth decade of life, often presenting as asymptomatic masses or ulcers with symptoms like pruritus, pain, or bleeding in advanced stages.
- Micro: Typically well-differentiated keratinizing carcinomas with keratin pearl formation; verrucous type shows cohesive or verruciform growth patterns with minimal atypia.
- Ancillary: p16 staining is usually negative, and p53 immunohistochemical staining can show overexpression or wildtype expression.
Reference Gallery:
Squamous cell carcinoma, HPV-independent. Keratinizing type. Well-differentiated squamous cell carcinoma with prominent keratin pearl formation and individual keratinization. This tumour was p16-negative and showed diffuse and strong nuclear staining for p53.
Squamous cell carcinoma, HPV-independent. Verrucous type.
Squamous cell carcinoma, HPV-independent. p53 immunohistochemical staining shows scattered nuclear positivity in the proliferating keratinocytes, representing wildtype expression.
Squamous cell carcinoma, HPV-independent. p53 immunohistochemistry shows positive staining. Tumoural cells show strong nuclear positivity (overexpression), which is consistent with missense mutation.

Q: Histologically, high-grade Squamous Intraepithelial Lesion of the Vulva shows architectural disorganization and atypical cells with nuclear hyperchromasia and high N:C ratios, frequently presenting with warty or [...] morphologic patterns.
High-grade squamous intraepithelial lesion of the vulva. Basaloid type. The epidermis is fully replaced by small atypical hyperchromatic cells with large nuclei, scant cytoplasm, and prominent mitotic activity.
High-grade squamous intraepithelial lesion of the vulva. Warty type. The epidermis has a warty architecture, with deep and wide rete ridges. There are koilocytic-like changes.
A: basaloid
Back Extra: Squamous Intraepithelial Lesion of the Vulva
- Clinical: About 60% of patients with a squamous intraepithelial lesion of the vulva present with pruritus and irritation, and a significant percentage are asymptomatic.
- Micro: High-grade squamous intraepithelial lesions of the vulva show nuclear hyperchromasia, high N:C ratios, and architectural disorganization with mitotic figures. The lesion can have basaloid or warty features.
- Ancillary: p16 block-type immunohistochemistry is overexpressed in squamous intraepithelial lesions of the vulva and is useful for ruling out HPV-independent differentiated intraepithelial neoplasia.
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High-grade squamous intraepithelial lesion with mixed basaloid and warty-type features. The epithelium is thickened and replaced by small atypical cells with hyperchromatic nuclei and scant cytoplasm. There is no prominent pleomorphism. There is architectural disorganization with a wind-blown appearance in the lower two thirds of the epithelium. Superficial parakeratosis is present. Abundant melanophages are visible in the papillary dermis.
High-grade squamous intraepithelial lesion of the vulva. Strong and diffuse block-type staining with p16. There is both cytoplasmic and nuclear positivity. The staining is particularly useful to rule out HPV-independent differentiated intraepithelial neoplasia with unusual basaloid or warty-like features. p16 is typically overexpressed in high-grade squamous intraepithelial lesions.
High-grade squamous intraepithelial lesion of the vulva. With mixed basaloid and differentiated features. The lesion shows prominent hyperkeratosis, hypergranulosis, and anastomosis of the interpapillary ridges. The lower thirds of the epidermis are disorganized and replaced by the immature hyperchromatic cells with high N:C ratios. Some mitotic figures are easily identified. The epithelium seems to mature superficially. In some areas, atypia appears to be limited to the basal layer.
High-grade squamous intraepithelial lesion of the vulva. Basaloid type. The epidermis is fully replaced by small atypical hyperchromatic cells with large nuclei, scant cytoplasm, and prominent mitotic activity.
High-grade squamous intraepithelial lesion of the vulva. Warty type. The epidermis has a warty architecture, with deep and wide rete ridges. There are koilocytic-like changes.

Q: To distinguish Squamous Intraepithelial Lesion of the Vulva from HPV-independent differentiated intraepithelial neoplasia, immunohistochemistry for [...] is utilized, which classically demonstrates strong and diffuse block-type positivity.
High-grade squamous intraepithelial lesion of the vulva. Strong and diffuse block-type staining with p16. There is both cytoplasmic and nuclear positivity. The staining is particularly useful to rule out HPV-independent differentiated intraepithelial neoplasia with unusual basaloid or warty-like features. p16 is typically overexpressed in high-grade squamous intraepithelial lesions.
A: p16
Back Extra: Squamous Intraepithelial Lesion of the Vulva
- Clinical: About 60% of patients with a squamous intraepithelial lesion of the vulva present with pruritus and irritation, and a significant percentage are asymptomatic.
- Micro: High-grade squamous intraepithelial lesions of the vulva show nuclear hyperchromasia, high N:C ratios, and architectural disorganization with mitotic figures. The lesion can have basaloid or warty features.
- Ancillary: p16 block-type immunohistochemistry is overexpressed in squamous intraepithelial lesions of the vulva and is useful for ruling out HPV-independent differentiated intraepithelial neoplasia.
Reference Gallery:
High-grade squamous intraepithelial lesion with mixed basaloid and warty-type features. The epithelium is thickened and replaced by small atypical cells with hyperchromatic nuclei and scant cytoplasm. There is no prominent pleomorphism. There is architectural disorganization with a wind-blown appearance in the lower two thirds of the epithelium. Superficial parakeratosis is present. Abundant melanophages are visible in the papillary dermis.
High-grade squamous intraepithelial lesion of the vulva. Strong and diffuse block-type staining with p16. There is both cytoplasmic and nuclear positivity. The staining is particularly useful to rule out HPV-independent differentiated intraepithelial neoplasia with unusual basaloid or warty-like features. p16 is typically overexpressed in high-grade squamous intraepithelial lesions.
High-grade squamous intraepithelial lesion of the vulva. With mixed basaloid and differentiated features. The lesion shows prominent hyperkeratosis, hypergranulosis, and anastomosis of the interpapillary ridges. The lower thirds of the epidermis are disorganized and replaced by the immature hyperchromatic cells with high N:C ratios. Some mitotic figures are easily identified. The epithelium seems to mature superficially. In some areas, atypia appears to be limited to the basal layer.
High-grade squamous intraepithelial lesion of the vulva. Basaloid type. The epidermis is fully replaced by small atypical hyperchromatic cells with large nuclei, scant cytoplasm, and prominent mitotic activity.
High-grade squamous intraepithelial lesion of the vulva. Warty type. The epidermis has a warty architecture, with deep and wide rete ridges. There are koilocytic-like changes.

Q: In Vulvar Intraepithelial Neoplasia, HPV-independent (often termed differentiated VIN), the abnormal atypical keratinocytes are characteristically confined to the [...] beneath a fully differentiated epithelium.
Differentiated VIN. The epidermis is thickened and has a parakeratotic surface reaction. The lower layer is composed of abnormal atypical keratinocytes with some mitotic figures.
Differentiated VIN. The epidermis shows hyperkeratosis, elongated and anastomosing rete ridges, and prominent intercellular bridges. Abnormal basal atypical keratinocytes are confined to the basal and parabasal layers, in a fully differentiated epithelium.
A: basal and parabasal layers
Back Extra: Vulvar Intraepithelial Neoplasia, HPV-independent
- Clinical: Vulvar Intraepithelial Neoplasia, HPV-independent often presents with pruritus, irritation, and pain, but up to 50% of cases are asymptomatic.
- Micro: The hallmark of differentiated VIN is the presence of abnormal atypical keratinocytes in the basal and parabasal layers, with a fully differentiated epithelium showing parakeratosis and anastomosing rete ridges.
- Ancillary: TP53 mutations are frequently identified in HPV-independent VIN, and abnormal p53 immunostaining (overexpression or null pattern) is relatively common.
Reference Gallery:
Differentiated VIN. p53 null staining. There is transition between normal epithelium (wildtype p53 staining) and abnormal, with no p53 staining in the differentiated VIN lesion.
Differentiated VIN. Abnormal p53 staining characterized by overexpression in the basal layer with mild suprabasal extension.
Differentiated VIN. The epidermis is thickened and has a parakeratotic surface reaction. The lower layer is composed of abnormal atypical keratinocytes with some mitotic figures.
Differentiated VIN. Occasionally, the basal layer can show striking cytological and architectural atypia, but there is still maturation towards the upper layers.
Differentiated VIN. The epidermis shows hyperkeratosis, elongated and anastomosing rete ridges, and prominent intercellular bridges. Abnormal basal atypical keratinocytes are confined to the basal and parabasal layers, in a fully differentiated epithelium.
Differentiated VIN. The epidermis shows hyperkeratosis. The rete ridges are elongated and anastomosing. The basal atypia is notable, with some atypical mitotic figures. Notably, abnormal keratinization is present, with dyskeratosis and a small abortive keratin pearl.

Q: Because it is frequently driven by TP53 mutations, Vulvar Intraepithelial Neoplasia, HPV-independent typically demonstrates an abnormal [...] immunostaining pattern, presenting as either striking basal overexpression or a complete null pattern.
Differentiated VIN. p53 null staining. There is transition between normal epithelium (wildtype p53 staining) and abnormal, with no p53 staining in the differentiated VIN lesion.
Differentiated VIN. Abnormal p53 staining characterized by overexpression in the basal layer with mild suprabasal extension.
A: p53
Back Extra: Vulvar Intraepithelial Neoplasia, HPV-independent
- Clinical: Vulvar Intraepithelial Neoplasia, HPV-independent often presents with pruritus, irritation, and pain, but up to 50% of cases are asymptomatic.
- Micro: The hallmark of differentiated VIN is the presence of abnormal atypical keratinocytes in the basal and parabasal layers, with a fully differentiated epithelium showing parakeratosis and anastomosing rete ridges.
- Ancillary: TP53 mutations are frequently identified in HPV-independent VIN, and abnormal p53 immunostaining (overexpression or null pattern) is relatively common.
Reference Gallery:
Differentiated VIN. p53 null staining. There is transition between normal epithelium (wildtype p53 staining) and abnormal, with no p53 staining in the differentiated VIN lesion.
Differentiated VIN. Abnormal p53 staining characterized by overexpression in the basal layer with mild suprabasal extension.
Differentiated VIN. The epidermis is thickened and has a parakeratotic surface reaction. The lower layer is composed of abnormal atypical keratinocytes with some mitotic figures.
Differentiated VIN. Occasionally, the basal layer can show striking cytological and architectural atypia, but there is still maturation towards the upper layers.
Differentiated VIN. The epidermis shows hyperkeratosis, elongated and anastomosing rete ridges, and prominent intercellular bridges. Abnormal basal atypical keratinocytes are confined to the basal and parabasal layers, in a fully differentiated epithelium.
Differentiated VIN. The epidermis shows hyperkeratosis. The rete ridges are elongated and anastomosing. The basal atypia is notable, with some atypical mitotic figures. Notably, abnormal keratinization is present, with dyskeratosis and a small abortive keratin pearl.

Q: A symmetrical, well-demarcated pigmented lesion composed of both intraepithelial junctional nests and a dermal component of regular melanocytes that exhibit zonal maturation is most consistent with an [...].
Compound naevus. This mainly junctional naevus has large intraepithelial nests of small melanocytes and a few dermal clusters.
Naevus. Compound naevus. Typical polypoid appearance of a predominantly dermal compound naevus at low magnification (HPS staining).
A: Acquired Melanocytic Naevus
Back Extra: Acquired Melanocytic Naevus
- Clinical: Acquired Melanocytic Naevus usually appears during infancy or in childbearing age, presenting as well-defined, pigmented lesions that are tan or brown, uniform in color, symmetrical, and well-demarcated.
- Micro: Histologically, genital Acquired Melanocytic Naevi are composed of junctional and dermal components, with dermal melanocytes showing zonal maturation and becoming smaller and more spindled with depth.
- Ancillary: BRAF p.Val600Glu mutations are occasionally detected, but no specific molecular tests are routinely used for diagnosis.
Reference Gallery:
Naevus. Compound naevus. Typical polypoid appearance of a predominantly dermal compound naevus at low magnification (HPS staining).
Naevus. Higher power of acquired compound naevus showing small, regular cells.
Compound naevus. This mainly junctional naevus has large intraepithelial nests of small melanocytes and a few dermal clusters.
Dermal naevus. Bland melanocytes are dispersed within the upper dermis.
Compound naevus. Nests of small melanocytes are present in a slightly verrucous epidermis. A few clusters are also visible in the upper dermis.

Q: The hallmark histologic feature of the dermal component in an Acquired Melanocytic Naevus is [...], characterized by the melanocytes progressively becoming smaller, more spindled, and blending into the stroma as they descend deeper into the dermis.
Naevus. Higher power of acquired compound naevus showing small, regular cells.
Dermal naevus. Bland melanocytes are dispersed within the upper dermis.
A: zonal maturation
Back Extra: Acquired Melanocytic Naevus
- Clinical: Acquired Melanocytic Naevus usually appears during infancy or in childbearing age, presenting as well-defined, pigmented lesions that are tan or brown, uniform in color, symmetrical, and well-demarcated.
- Micro: Histologically, genital Acquired Melanocytic Naevi are composed of junctional and dermal components, with dermal melanocytes showing zonal maturation and becoming smaller and more spindled with depth.
- Ancillary: BRAF p.Val600Glu mutations are occasionally detected, but no specific molecular tests are routinely used for diagnosis.
Reference Gallery:
Naevus. Compound naevus. Typical polypoid appearance of a predominantly dermal compound naevus at low magnification (HPS staining).
Naevus. Higher power of acquired compound naevus showing small, regular cells.
Compound naevus. This mainly junctional naevus has large intraepithelial nests of small melanocytes and a few dermal clusters.
Dermal naevus. Bland melanocytes are dispersed within the upper dermis.
Compound naevus. Nests of small melanocytes are present in a slightly verrucous epidermis. A few clusters are also visible in the upper dermis.

Q: Histologically, a Blue Naevus typically presents with poorly circumscribed dermal aggregates of heavily pigmented, [...] melanocytes associated with stromal fibroplasia (sclerosis).
Blue naevus. Dermal dendritic pigmented melanocytes in a sclerotic background (HPS staining).
A: dendritic
Back Extra: Blue Naevus
- Clinical: Blue naevus typically presents as a small brown or black macular or papular lesion with a blue hue. In adults, vulvar melanocytic naevi are generally found in women in the reproductive age group.
- Micro: Blue naevi are located in the subepithelial tissue and form poorly circumscribed aggregates of small, darkly pigmented dendritic or spindled melanocytes associated with stromal fibroplasia.
- Ancillary: Blue naevi are associated with activating mutations in GNAQ, GNA11, or PLCB4 (or less frequently in CYSLTR2).
Reference Gallery:
Cellular blue naevus. Sheets of spindled bland pigmented melanocytes.
Blue naevus. Dermal dendritic pigmented melanocytes in a sclerotic background (HPS staining).

Q: The cellular variant of a Blue Naevus is characterized histologically by dense sheets or fascicles of bland, pigmented, [...] melanocytes, often lacking prominent sclerosis.
Cellular blue naevus. Sheets of spindled bland pigmented melanocytes.
A: spindled
Back Extra: Blue Naevus
- Clinical: Blue naevus typically presents as a small brown or black macular or papular lesion with a blue hue. In adults, vulvar melanocytic naevi are generally found in women in the reproductive age group.
- Micro: Blue naevi are located in the subepithelial tissue and form poorly circumscribed aggregates of small, darkly pigmented dendritic or spindled melanocytes associated with stromal fibroplasia.
- Ancillary: Blue naevi are associated with activating mutations in GNAQ, GNA11, or PLCB4 (or less frequently in CYSLTR2).
Reference Gallery:
Cellular blue naevus. Sheets of spindled bland pigmented melanocytes.
Blue naevus. Dermal dendritic pigmented melanocytes in a sclerotic background (HPS staining).

Q: Histologically, a distinguishing feature of the dermal component in a Congenital Melanocytic Naevus is the deep tracking and maturation of melanocytes around skin appendages (such as the pilosebaceous unit shown), a pattern known as [...] growth.
Congenital naevus. High-power view showing maturation of naevus cells around a pilosebaceous unit.
A: periadnexal
Back Extra: Congenital Melanocytic Naevus
- Clinical: Congenital melanocytic naevi are well-defined, tan to brown papules, nodules, or plaques that may grow and change color within the first 6 years of life.
- Micro: Junctional congenital melanocytic naevi display intraepidermal single and nested melanocytes, while dermal and compound types exhibit mature melanocytes with perivascular and periadnexal growth.
- Ancillary: Most large congenital melanocytic naevi harbor exon 3 NRAS mutations, with smaller naevi sometimes harboring BRAF p.Val600Glu mutations.
Reference Gallery:
Congenital naevus. High-power view showing maturation of naevus cells around a pilosebaceous unit.

Q: A skin biopsy reveals mature dermal melanocytes exhibiting deep perivascular and periadnexal growth (tracking around a pilosebaceous unit). This morphologic pattern is the histologic hallmark of a(n) [...].
Congenital naevus. High-power view showing maturation of naevus cells around a pilosebaceous unit.
A: Congenital Melanocytic Naevus
Back Extra: Congenital Melanocytic Naevus
- Clinical: Congenital melanocytic naevi are well-defined, tan to brown papules, nodules, or plaques that may grow and change color within the first 6 years of life.
- Micro: Junctional congenital melanocytic naevi display intraepidermal single and nested melanocytes, while dermal and compound types exhibit mature melanocytes with perivascular and periadnexal growth.
- Ancillary: Most large congenital melanocytic naevi harbor exon 3 NRAS mutations, with smaller naevi sometimes harboring BRAF p.Val600Glu mutations.
Reference Gallery:
Congenital naevus. High-power view showing maturation of naevus cells around a pilosebaceous unit.

Q: Atypical Melanocytic Naevus of Genital Type characteristically shows large, confluent junctional nests of melanocytes that exhibit a notable [...], overlying dispersed dermal nests in a fibrotic background.
Atypical genital naevus. Confluent junctional nests of medium-sized pigmented melanocytes with loss of intercellular cohesion. Small dermal nests in a fibrotic background with melanophages.
Atypical genital naevus. A higher-power view of Fig. #10756, showing confluent junctional nests of medium-sized pigmented melanocytes with loss of intercellular cohesion. Small dermal nests in a fibrotic background with melanophages.
A: loss of intercellular cohesion
Back Extra: Atypical Melanocytic Naevus of Genital Type
- Clinical: Atypical Melanocytic Naevus of Genital Type (AMNGT) is commonly found in young women in their third decade of life, presenting as a slow-growing, irregularly pigmented (tan, brown) papule, often > 6 mm.
- Micro: AMNGT shows large, irregularly shaped and confluent junctional nests of melanocytes with loss of intercellular cohesion, and a dermal component with dispersed nests or sheets of smaller melanocytes in a fibrotic background.
- Ancillary: Ancillary studies are not clinically relevant for the diagnosis of AMNGT.
Reference Gallery:
Atypical genital naevus. Confluent junctional nests of medium-sized pigmented melanocytes with loss of intercellular cohesion. Small dermal nests in a fibrotic background with melanophages.
Atypical genital naevus. A higher-power view of Fig. #10756, showing confluent junctional nests of medium-sized pigmented melanocytes with loss of intercellular cohesion. Small dermal nests in a fibrotic background with melanophages.

Q: Histologically, a Dysplastic Melanocytic Naevus demonstrates architectural disorder that is classically characterized by [...] across the rete ridges.
Dysplastic naevus. The lesion consists of junctional nests bridging the rete ridges of a papillomatous epidermis.
Dysplastic naevus. A higher-power view of junctional nests bridging the rete ridges of a papillomatous epidermis (see Fig. #10768).
A: bridging junctional nests
Back Extra: Dysplastic Melanocytic Naevus
- Clinical: Dysplastic melanocytic naevi are often > 6 mm, irregularly bordered macules or papules with central pink tones in a background of tan to brown at the periphery, most frequently found on the cutaneous labia majora.
- Micro: Histologically, dysplastic melanocytic naevi show architectural disorder with bridging junctional nests, variation in nest size and shape, and a lentiginous junctional component with a well-developed shoulder.
- Ancillary: Dysplastic melanocytic naevi are associated with activating mutations in BRAF and NRAS, similar to other acquired melanocytic naevi.
Reference Gallery:
Dysplastic naevus. The lesion consists of junctional nests bridging the rete ridges of a papillomatous epidermis.
Dysplastic naevus. A higher-power view of junctional nests bridging the rete ridges of a papillomatous epidermis (see Fig. #10768).

Q: Microscopically, [...] is a tumor typically formed by sheets or expansive nodules of large, pleomorphic epithelioid or spindle malignant melanocytic cells, often accompanied by a subepithelial lymphocytic infiltrate.
Vulvar melanoma. Invasive component: the large and pleomorphic invasive melanoma cells are epithelioid and spindle in shape. An occasional mitosis is present, and there is a small amount of melanin pigment.
Melanoma. A higher-power view of the invasive component of a vaginal melanoma, which is composed of large pleomorphic epithelioid cells.
A: Mucosal Melanoma
Back Extra: Mucosal Melanoma
- Clinical: Most patients are postmenopausal, with a median age of 65 years. Symptoms and signs depend on the anatomical location and include the presence of a mass, a macule or a non-pigmented lesion, and/or bleeding.
- Micro: The tumour is usually formed by sheets or expansive nodules of large pleomorphic epithelioid or spindle malignant melanocytic cells. Necrosis is uncommon. A subepithelial lymphocytic infiltrate is common.
- Ancillary: BRAF and KIT tumour mutation testing may be useful in patients for whom targeted therapies are being considered.
Reference Gallery:
Vulvar melanoma. In situ melanoma showing a confluent nested and lentiginous proliferation of atypical melanocytes involving the basal epidermis. An occasional cell shows pagetoid spread.
Vulvar melanoma. Invasive component: the large and pleomorphic invasive melanoma cells are epithelioid and spindle in shape. An occasional mitosis is present, and there is a small amount of melanin pigment.
Melanoma. A higher-power view of the invasive component of a vaginal melanoma, which is composed of large pleomorphic epithelioid cells.
Melanoma. In situ mucosal melanoma component showing large pleomorphic melanoma cells with an epithelioid shape, involving all layers of the vaginal squamous mucosa. A mild lymphocytic infiltrate is present in the superficial underlying stroma.

Q: In Mucosal Melanoma, the in situ component can demonstrate a nested and lentiginous proliferation of atypical melanocytes with upward intraepithelial migration, a feature known as [...].
Vulvar melanoma. In situ melanoma showing a confluent nested and lentiginous proliferation of atypical melanocytes involving the basal epidermis. An occasional cell shows pagetoid spread.
Melanoma. In situ mucosal melanoma component showing large pleomorphic melanoma cells with an epithelioid shape, involving all layers of the vaginal squamous mucosa. A mild lymphocytic infiltrate is present in the superficial underlying stroma.
A: pagetoid spread
Back Extra: Mucosal Melanoma
- Clinical: Most patients are postmenopausal, with a median age of 65 years. Symptoms and signs depend on the anatomical location and include the presence of a mass, a macule or a non-pigmented lesion, and/or bleeding.
- Micro: The tumour is usually formed by sheets or expansive nodules of large pleomorphic epithelioid or spindle malignant melanocytic cells. Necrosis is uncommon. A subepithelial lymphocytic infiltrate is common.
- Ancillary: BRAF and KIT tumour mutation testing may be useful in patients for whom targeted therapies are being considered.
Reference Gallery:
Vulvar melanoma. In situ melanoma showing a confluent nested and lentiginous proliferation of atypical melanocytes involving the basal epidermis. An occasional cell shows pagetoid spread.
Vulvar melanoma. Invasive component: the large and pleomorphic invasive melanoma cells are epithelioid and spindle in shape. An occasional mitosis is present, and there is a small amount of melanin pigment.
Melanoma. A higher-power view of the invasive component of a vaginal melanoma, which is composed of large pleomorphic epithelioid cells.
Melanoma. In situ mucosal melanoma component showing large pleomorphic melanoma cells with an epithelioid shape, involving all layers of the vaginal squamous mucosa. A mild lymphocytic infiltrate is present in the superficial underlying stroma.

Q: Histopathologically, Angiomyofibroblastoma consists of alternating zones of cellularity with prominent thin-walled vessels in an edematous matrix, and the tumor cells frequently exhibit a characteristic [...] appearance.
Angiomyofibroblastoma. Tumour cells and vessels are set in a loose oedematous stroma.
Angiomyofibroblastoma. Binucleated and multinucleated cells are frequent and may have a plasmacytoid appearance.
A: plasmacytoid
Back Extra: Angiomyofibroblastoma
- Clinical: Patients typically present with a painless mass misinterpreted as a cyst. Angiomyofibroblastoma is usually smaller than 5 cm and commonly occurs in reproductive-age women.
- Micro: Histopathology shows alternating zones of cellularity and prominent small to medium-sized thin-walled vessels in an oedematous matrix. Tumour cells often have a plasmacytoid appearance.
- Ancillary: Immunohistochemistry shows strong and diffuse positive staining for desmin, and tumour cells are consistently positive for ER and PR.
Reference Gallery:
Angiomyofibroblastoma. The tumour is more cellular and vascular than aggressive angiomyxoma. Note the adipocytic component.
Angiomyofibroblastoma. Tumour cells and vessels are set in a loose oedematous stroma.
Angiomyofibroblastoma. Binucleated and multinucleated cells are frequent and may have a plasmacytoid appearance.

Q: Microscopically, Angiomyofibroblastoma is distinct from aggressive angiomyxoma as it is significantly more cellular and vascular, and may also feature a prominent [...] component.
Angiomyofibroblastoma. The tumour is more cellular and vascular than aggressive angiomyxoma. Note the adipocytic component.
A: adipocytic
Back Extra: Angiomyofibroblastoma
- Clinical: Patients typically present with a painless mass misinterpreted as a cyst. Angiomyofibroblastoma is usually smaller than 5 cm and commonly occurs in reproductive-age women.
- Micro: Histopathology shows alternating zones of cellularity and prominent small to medium-sized thin-walled vessels in an oedematous matrix. Tumour cells often have a plasmacytoid appearance.
- Ancillary: Immunohistochemistry shows strong and diffuse positive staining for desmin, and tumour cells are consistently positive for ER and PR.
Reference Gallery:
Angiomyofibroblastoma. The tumour is more cellular and vascular than aggressive angiomyxoma. Note the adipocytic component.
Angiomyofibroblastoma. Tumour cells and vessels are set in a loose oedematous stroma.
Angiomyofibroblastoma. Binucleated and multinucleated cells are frequent and may have a plasmacytoid appearance.

Q: Histologically, Myofibroblastoma presents as a well-circumscribed tumor with spindle cells arranged in short fascicles, separated by characteristic broad bands of [...].
Myofibroblastoma. These tumours are characteristically composed of spindle cells arranged in short fascicles, with interspersed broad bands of hyalinized collagen.
A: hyalinized collagen
Back Extra: Myofibroblastoma
- Clinical: Myofibroblastomas typically present as slow-growing, painless masses, most commonly in the inguinal/groin area, including the vulva/vagina and perineum, and predominantly affect adults in their fifth or sixth decade of life.
- Micro: These tumours are unencapsulated but well-circumscribed, composed of spindle cells arranged in short fascicles, with interspersed broad bands of hyalinized collagen and a variable adipocytic component.
- Ancillary: Immunohistochemically, myofibroblastomas typically show diffuse coexpression of desmin and CD34, with approximately one-third of cases positive for SMA and about 90% showing loss of nuclear RB1.
Reference Gallery:
Myofibroblastoma. These tumours are characteristically composed of spindle cells arranged in short fascicles, with interspersed broad bands of hyalinized collagen.
Myofibroblastoma. The spindle cells have short stubby nuclei with finely dispersed chromatin and eosinophilic to amphophilic cytoplasm.

Q: At higher magnification, the spindle cells of Myofibroblastoma exhibit characteristic short, [...] nuclei with finely dispersed chromatin and eosinophilic to amphophilic cytoplasm.
Myofibroblastoma. The spindle cells have short stubby nuclei with finely dispersed chromatin and eosinophilic to amphophilic cytoplasm.
A: stubby
Back Extra: Myofibroblastoma
- Clinical: Myofibroblastomas typically present as slow-growing, painless masses, most commonly in the inguinal/groin area, including the vulva/vagina and perineum, and predominantly affect adults in their fifth or sixth decade of life.
- Micro: These tumours are unencapsulated but well-circumscribed, composed of spindle cells arranged in short fascicles, with interspersed broad bands of hyalinized collagen and a variable adipocytic component.
- Ancillary: Immunohistochemically, myofibroblastomas typically show diffuse coexpression of desmin and CD34, with approximately one-third of cases positive for SMA and about 90% showing loss of nuclear RB1.
Reference Gallery:
Myofibroblastoma. These tumours are characteristically composed of spindle cells arranged in short fascicles, with interspersed broad bands of hyalinized collagen.
Myofibroblastoma. The spindle cells have short stubby nuclei with finely dispersed chromatin and eosinophilic to amphophilic cytoplasm.

Q: Histologically, Cellular Angiofibroma features short spindle-shaped cells, prominent rounded vessels, and an admixture of frequent [...].
Cellular angiofibroma. At high power, the spindle cells have short stubby nuclei and indistinct cytoplasm, resembling spindle cell lipoma. Note the admixed mast cells and rounded vessels.
A: mast cells
Back Extra: Cellular Angiofibroma
- Clinical: Patients usually present with a slow-growing, painless mass, most commonly misdiagnosed as a Bartholin gland cyst.
- Micro: Tumours are well circumscribed, composed of short spindle-shaped cells in an oedematous to fibrous stroma with prominent blood vessels and frequent mast cells.
- Ancillary: CD34 expression is documented in 30–60% of cases, with variable expression of SMA and desmin in 10–20%.
Reference Gallery:
Cellular angiofibroma. Note the usual circumscription, varying cellularity, and prominent vessels with hyaline walls.
Cellular angiofibroma. At high power, the spindle cells have short stubby nuclei and indistinct cytoplasm, resembling spindle cell lipoma. Note the admixed mast cells and rounded vessels.
Cellular angiofibroma. Degenerative changes such as stromal oedema, patchy chronic inflammation, and mild nuclear atypia are more common in male patients.
Cellular angiofibroma. About 50% of cases contain variably prominent mature adipocytes.
Cellular angiofibroma. Rare cases show small aggregates of highly atypical cells, as seen here, and occasional cases may show overtly sarcomatous morphology but appear to retain benign behaviour.

Q: In about 50% of Cellular Angiofibroma cases, the tumor stroma contains variably prominent mature [...].
Cellular angiofibroma. About 50% of cases contain variably prominent mature adipocytes.
A: adipocytes
Back Extra: Cellular Angiofibroma
- Clinical: Patients usually present with a slow-growing, painless mass, most commonly misdiagnosed as a Bartholin gland cyst.
- Micro: Tumours are well circumscribed, composed of short spindle-shaped cells in an oedematous to fibrous stroma with prominent blood vessels and frequent mast cells.
- Ancillary: CD34 expression is documented in 30–60% of cases, with variable expression of SMA and desmin in 10–20%.
Reference Gallery:
Cellular angiofibroma. Note the usual circumscription, varying cellularity, and prominent vessels with hyaline walls.
Cellular angiofibroma. At high power, the spindle cells have short stubby nuclei and indistinct cytoplasm, resembling spindle cell lipoma. Note the admixed mast cells and rounded vessels.
Cellular angiofibroma. Degenerative changes such as stromal oedema, patchy chronic inflammation, and mild nuclear atypia are more common in male patients.
Cellular angiofibroma. About 50% of cases contain variably prominent mature adipocytes.
Cellular angiofibroma. Rare cases show small aggregates of highly atypical cells, as seen here, and occasional cases may show overtly sarcomatous morphology but appear to retain benign behaviour.

Q: Cellular Angiofibroma is typically a well-circumscribed tumor characterized by short spindle cells in an edematous to fibrous stroma with numerous, prominent [...] that often have hyalinized walls.
Cellular angiofibroma. Note the usual circumscription, varying cellularity, and prominent vessels with hyaline walls.
A: blood vessels
Back Extra: Cellular Angiofibroma
- Clinical: Patients usually present with a slow-growing, painless mass, most commonly misdiagnosed as a Bartholin gland cyst.
- Micro: Tumours are well circumscribed, composed of short spindle-shaped cells in an oedematous to fibrous stroma with prominent blood vessels and frequent mast cells.
- Ancillary: CD34 expression is documented in 30–60% of cases, with variable expression of SMA and desmin in 10–20%.
Reference Gallery:
Cellular angiofibroma. Note the usual circumscription, varying cellularity, and prominent vessels with hyaline walls.
Cellular angiofibroma. At high power, the spindle cells have short stubby nuclei and indistinct cytoplasm, resembling spindle cell lipoma. Note the admixed mast cells and rounded vessels.
Cellular angiofibroma. Degenerative changes such as stromal oedema, patchy chronic inflammation, and mild nuclear atypia are more common in male patients.
Cellular angiofibroma. About 50% of cases contain variably prominent mature adipocytes.
Cellular angiofibroma. Rare cases show small aggregates of highly atypical cells, as seen here, and occasional cases may show overtly sarcomatous morphology but appear to retain benign behaviour.

Q: A polypoid lesion featuring a central fibrovascular core, overlying squamous epithelium, and prominent stellate and multinucleated stromal cells is characteristic of a [...].
Fibroepithelial stromal polyp. Fibroepithelial stromal polyps are polypoid lesions with a variably cellular stroma, central fibrovascular core, and overlying squamous epithelium.
Fibroepithelial stromal polyp. Increased stromal cellularity and mitotic activity are present.
A: Fibroepithelial Stromal Polyp
Back Extra: Fibroepithelial Stromal Polyp
- Clinical: Fibroepithelial stromal polyps are often discovered incidentally and may present with symptoms such as bleeding, discharge, or discomfort.
- Micro: The lesions are characterized by a central fibrovascular core, a polypoid stromal proliferation, and overlying squamous epithelium. Stellate and multinucleated stromal cells are prominent.
- Ancillary: The stromal cells are consistently positive for desmin, ER, and PR, and sometimes SMA.
Reference Gallery:
Fibroepithelial stromal polyp. Fibroepithelial stromal polyps are polypoid lesions with a variably cellular stroma, central fibrovascular core, and overlying squamous epithelium.
Fibroepithelial stromal polyp. Increased stromal cellularity and mitotic activity are present.
Fibroepithelial stromal polyp. The stromal cells are positive for desmin.

Q: Immunohistochemically, the prominent stellate and multinucleated stromal cells in a Fibroepithelial Stromal Polyp are characteristically positive for ER, PR, and [...].
Fibroepithelial stromal polyp. The stromal cells are positive for desmin.
A: desmin
Back Extra: Fibroepithelial Stromal Polyp
- Clinical: Fibroepithelial stromal polyps are often discovered incidentally and may present with symptoms such as bleeding, discharge, or discomfort.
- Micro: The lesions are characterized by a central fibrovascular core, a polypoid stromal proliferation, and overlying squamous epithelium. Stellate and multinucleated stromal cells are prominent.
- Ancillary: The stromal cells are consistently positive for desmin, ER, and PR, and sometimes SMA.
Reference Gallery:
Fibroepithelial stromal polyp. Fibroepithelial stromal polyps are polypoid lesions with a variably cellular stroma, central fibrovascular core, and overlying squamous epithelium.
Fibroepithelial stromal polyp. Increased stromal cellularity and mitotic activity are present.
Fibroepithelial stromal polyp. The stromal cells are positive for desmin.

Q: Microscopically, a granular cell tumor is characterized by sheets and nests of large, monotonous cells with centrally situated nuclei and an intensely eosinophilic, [...] cytoplasm.
Granular cell tumour. Medium-power view showing a well-circumscribed but unencapsulated tumour with large nests of eosinophilic cells with copious cytoplasm.
Granular cell tumour. High-power view showing features characteristic of granular cell tumour: moderate-sized cells with abundant granular, eosinophilic cytoplasm and rounded nuclei with fine chromatin.
A: granular
Back Extra: Granular Cell Tumour
- Clinical: Granular cell tumour typically presents as a slow-growing, mobile, non-tender mass, usually < 4 cm, often found in black women in the fourth to sixth decade of life.
- Micro: Characterized by sheets, nests, and trabeculae of large, monotonous epithelioid to polygonal cells with intensely eosinophilic, granular cytoplasm and centrally situated nuclei.
- Ancillary: Loss-of-function mutations in ATP6AP1 or ATP6AP2 are useful in diagnosing granular cell tumour, and immunohistochemistry shows reactivity for S100, SOX10, nestin, inhibin, and calretinin.
Reference Gallery:
Granular cell tumour. Medium-power view showing a well-circumscribed but unencapsulated tumour with large nests of eosinophilic cells with copious cytoplasm.
Granular cell tumour. High-power view showing features characteristic of granular cell tumour: moderate-sized cells with abundant granular, eosinophilic cytoplasm and rounded nuclei with fine chromatin.
Granular cell tumour. Pseudoepitheliomatous hyperplasia overlying a granular cell tumour from the vulva of a 45-year-old woman. Extensive pseudoepitheliomatous hyperplasia can simulate squamous cell carcinoma, a notorious diagnostic pitfall.

Q: A notorious diagnostic pitfall of a granular cell tumor is the presence of extensive [...] in the overlying epithelium, which can mimic squamous cell carcinoma.
Granular cell tumour. Pseudoepitheliomatous hyperplasia overlying a granular cell tumour from the vulva of a 45-year-old woman. Extensive pseudoepitheliomatous hyperplasia can simulate squamous cell carcinoma, a notorious diagnostic pitfall.
A: pseudoepitheliomatous hyperplasia
Back Extra: Granular Cell Tumour
- Clinical: Granular cell tumour typically presents as a slow-growing, mobile, non-tender mass, usually < 4 cm, often found in black women in the fourth to sixth decade of life.
- Micro: Characterized by sheets, nests, and trabeculae of large, monotonous epithelioid to polygonal cells with intensely eosinophilic, granular cytoplasm and centrally situated nuclei.
- Ancillary: Loss-of-function mutations in ATP6AP1 or ATP6AP2 are useful in diagnosing granular cell tumour, and immunohistochemistry shows reactivity for S100, SOX10, nestin, inhibin, and calretinin.
Reference Gallery:
Granular cell tumour. Medium-power view showing a well-circumscribed but unencapsulated tumour with large nests of eosinophilic cells with copious cytoplasm.
Granular cell tumour. High-power view showing features characteristic of granular cell tumour: moderate-sized cells with abundant granular, eosinophilic cytoplasm and rounded nuclei with fine chromatin.
Granular cell tumour. Pseudoepitheliomatous hyperplasia overlying a granular cell tumour from the vulva of a 45-year-old woman. Extensive pseudoepitheliomatous hyperplasia can simulate squamous cell carcinoma, a notorious diagnostic pitfall.

Q: Microscopically, a Leiomyoma is classically composed of intersecting fascicles of cytologically bland [...] with ample eosinophilic cytoplasm and elongated nuclei.
Leiomyoma. Leiomyomas of the lower genital tract most commonly have typical spindled morphology.
A: spindle cells
Back Extra: Leiomyoma
- Clinical: Lower genital tract leiomyomas are usually < 5 cm and may present as a slow-growing, painless mass, often clinically suspected to be a cyst.
- Micro: Leiomyomas are composed of intersecting fascicles of cytologically bland spindle cells with ample eosinophilic cytoplasm and elongated nuclei. Hyalinized or myxoedematous stroma may be present.
- Ancillary: Not clinically relevant for diagnosis or management.
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Leiomyoma. Leiomyomas of the lower genital tract most commonly have typical spindled morphology.
Leiomyoma. Some leiomyomas of the lower genital tract have prominent hyalinization.

Q: In addition to the classic intersecting fascicles, the stroma of a lower genital tract Leiomyoma can occasionally exhibit myxedematous changes or prominent [...].
Leiomyoma. Some leiomyomas of the lower genital tract have prominent hyalinization.
A: hyalinization
Back Extra: Leiomyoma
- Clinical: Lower genital tract leiomyomas are usually < 5 cm and may present as a slow-growing, painless mass, often clinically suspected to be a cyst.
- Micro: Leiomyomas are composed of intersecting fascicles of cytologically bland spindle cells with ample eosinophilic cytoplasm and elongated nuclei. Hyalinized or myxoedematous stroma may be present.
- Ancillary: Not clinically relevant for diagnosis or management.
Reference Gallery:
Leiomyoma. Leiomyomas of the lower genital tract most commonly have typical spindled morphology.
Leiomyoma. Some leiomyomas of the lower genital tract have prominent hyalinization.

Q: On gross examination, a Lipoma characteristically presents as a [...] enclosed by a thin fibrous capsule.
Lipoma. On gross examination, a lobulated yellow mass with a thin fibrous capsule is characteristic.
A: lobulated yellow mass
Back Extra: Lipoma
- Clinical: Lipoma presents as a superficial, solitary, soft, mobile, and painless mass, most commonly in the vulva, and is seen in adults of reproductive age as well as children.
- Micro: Tumours consist of mature adipocytes arranged in sheets and/or lobules separated by thin fibrous septa, with no cytological atypia or lipoblasts.
- Ancillary: In larger tumours (> 10 cm), absence of MDM2 or CDK4 expression by IHC and lack of MDM2 amplification helps exclude atypical lipomatous tumour (ALT).
Reference Gallery:
Lipoma. On gross examination, a lobulated yellow mass with a thin fibrous capsule is characteristic.

Q: In the evaluation of large soft tissue tumors (> 10 cm), the diagnosis of a Lipoma is supported by the absence of CDK4 and [...] expression or amplification, which helps exclude an atypical lipomatous tumor.
Lipoma. On gross examination, a lobulated yellow mass with a thin fibrous capsule is characteristic.
A: MDM2
Back Extra: Lipoma
- Clinical: Lipoma presents as a superficial, solitary, soft, mobile, and painless mass, most commonly in the vulva, and is seen in adults of reproductive age as well as children.
- Micro: Tumours consist of mature adipocytes arranged in sheets and/or lobules separated by thin fibrous septa, with no cytological atypia or lipoblasts.
- Ancillary: In larger tumours (> 10 cm), absence of MDM2 or CDK4 expression by IHC and lack of MDM2 amplification helps exclude atypical lipomatous tumour (ALT).
Reference Gallery:
Lipoma. On gross examination, a lobulated yellow mass with a thin fibrous capsule is characteristic.

Q: Histologically, Lipoblastoma-like tumor of the vulva displays a lobulated architecture containing mature adipocytes, spindle cells, and characteristic bland [...] within a myxoid matrix.
Lipoblastoma-like tumour of the vulva. Lobulated architecture outlined by thin or thick fibrous septa and variably prominent myxoid matrix.
Lipoblastoma-like tumour of the vulva. Variable proportions of mature adipocytes, bland lipoblasts, and spindle cells with short stubby nuclei.
A: lipoblasts
Back Extra: Lipoblastoma-like tumour of the vulva
- Clinical: Lipoblastoma-like tumour of the vulva is an enlarging, sometimes painful mass, typically occurring in women of reproductive age.
- Micro: Tumours show a lobulated growth pattern with a mixture of mature adipocytes, lipoblasts, and spindle cells, and a variably prominent myxoid matrix.
- Ancillary: The absence of DDIT3 and PLAG1 rearrangements supports the distinction from myxoid liposarcoma and lipoblastoma.
Reference Gallery:
Lipoblastoma-like tumour of the vulva. Lobulated architecture outlined by thin or thick fibrous septa and variably prominent myxoid matrix.
Lipoblastoma-like tumour of the vulva. Variable proportions of mature adipocytes, bland lipoblasts, and spindle cells with short stubby nuclei.
Lipoblastoma-like tumour of the vulva. Prominent thin-walled branching vessels.

Q: In Lipoblastoma-like tumor of the vulva, the variably prominent myxoid stroma often contains prominent, thin-walled, [...] vessels, which can morphologically mimic myxoid liposarcoma.
Lipoblastoma-like tumour of the vulva. Prominent thin-walled branching vessels.
A: branching
Back Extra: Lipoblastoma-like tumour of the vulva
- Clinical: Lipoblastoma-like tumour of the vulva is an enlarging, sometimes painful mass, typically occurring in women of reproductive age.
- Micro: Tumours show a lobulated growth pattern with a mixture of mature adipocytes, lipoblasts, and spindle cells, and a variably prominent myxoid matrix.
- Ancillary: The absence of DDIT3 and PLAG1 rearrangements supports the distinction from myxoid liposarcoma and lipoblastoma.
Reference Gallery:
Lipoblastoma-like tumour of the vulva. Lobulated architecture outlined by thin or thick fibrous septa and variably prominent myxoid matrix.
Lipoblastoma-like tumour of the vulva. Variable proportions of mature adipocytes, bland lipoblasts, and spindle cells with short stubby nuclei.
Lipoblastoma-like tumour of the vulva. Prominent thin-walled branching vessels.

Q: Microscopically, Prepubertal Vulvar Fibroma typically presents as a hypocellular and patternless proliferation of bland spindle cells exhibiting infiltrative growth through pre-existing [...] and blood vessels.
Prepubertal vulvar fibroma. Tumours are hypocellular and patternless, with infiltrative growth through pre-existing adipose tissue and blood vessels.
Prepubertal vulvar fibroma. Bland spindle cells set within a fibrous stroma with abundant stromal collagen fibres.
A: adipose tissue
Back Extra: Prepubertal Vulvar Fibroma
- Clinical: Prepubertal vulvar fibroma presents as a unilateral, painless mass in the vulvar region of prepubertal girls, often enlarging over months to 3 years.
- Micro: The lesion is hypocellular and patternless, with bland spindle cells in a fibrous stroma and infiltrative growth through pre-existing adipose tissue and blood vessels.
- Ancillary: CD34 staining is typically multifocal to strong and diffuse, while S100, SMA, and desmin are consistently negative.
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Prepubertal vulvar fibroma. Tumours are hypocellular and patternless, with infiltrative growth through pre-existing adipose tissue and blood vessels.
Prepubertal vulvar fibroma. Bland spindle cells set within a fibrous stroma with abundant stromal collagen fibres.

Q: A hypocellular, patternless spindle cell tumor occurring as a unilateral, painless mass in young girls, which uniquely exhibits infiltrative growth through vulvar fat and blood vessels, is highly characteristic of a [...].
Prepubertal vulvar fibroma. Tumours are hypocellular and patternless, with infiltrative growth through pre-existing adipose tissue and blood vessels.
A: Prepubertal Vulvar Fibroma
Back Extra: Prepubertal Vulvar Fibroma
- Clinical: Prepubertal vulvar fibroma presents as a unilateral, painless mass in the vulvar region of prepubertal girls, often enlarging over months to 3 years.
- Micro: The lesion is hypocellular and patternless, with bland spindle cells in a fibrous stroma and infiltrative growth through pre-existing adipose tissue and blood vessels.
- Ancillary: CD34 staining is typically multifocal to strong and diffuse, while S100, SMA, and desmin are consistently negative.
Reference Gallery:
Prepubertal vulvar fibroma. Tumours are hypocellular and patternless, with infiltrative growth through pre-existing adipose tissue and blood vessels.
Prepubertal vulvar fibroma. Bland spindle cells set within a fibrous stroma with abundant stromal collagen fibres.

Q: A soft tissue tumor characterized microscopically by a multinodular proliferation of well-delineated myxoid lobules, bland spindle cells, and thin-walled curvilinear blood vessels is the classic presentation of [...].
Superficial angiomyxoma. The tumour typically shows a well-demarcated growth of myxoid lobules.
Superficial angiomyxoma. The tumour is characteristically composed of bland spindle cells and curvilinear vasculature set within a copious myxoid matrix.
A: superficial angiomyxoma
Back Extra: Superficial Angiomyxoma
- Clinical: Superficial angiomyxomas classically present as slow-growing, painless, and often exophytic lesions in patients of reproductive age.
- Micro: Characterized by multinodular proliferation of well-delineated myxoid lobules with spindled and stellate cells and thin-walled curvilinear blood vessels.
- Ancillary: Not clinically relevant; diagnosis is primarily based on histopathological examination.
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Superficial angiomyxoma. The tumour typically shows a well-demarcated growth of myxoid lobules.
Superficial angiomyxoma. The tumour is characteristically composed of bland spindle cells and curvilinear vasculature set within a copious myxoid matrix.

Q: In superficial angiomyxoma, the characteristic thin-walled blood vessels set within the copious myxoid matrix typically exhibit a distinct [...] architecture.
Superficial angiomyxoma. The tumour is characteristically composed of bland spindle cells and curvilinear vasculature set within a copious myxoid matrix.
A: curvilinear
Back Extra: Superficial Angiomyxoma
- Clinical: Superficial angiomyxomas classically present as slow-growing, painless, and often exophytic lesions in patients of reproductive age.
- Micro: Characterized by multinodular proliferation of well-delineated myxoid lobules with spindled and stellate cells and thin-walled curvilinear blood vessels.
- Ancillary: Not clinically relevant; diagnosis is primarily based on histopathological examination.
Reference Gallery:
Superficial angiomyxoma. The tumour typically shows a well-demarcated growth of myxoid lobules.
Superficial angiomyxoma. The tumour is characteristically composed of bland spindle cells and curvilinear vasculature set within a copious myxoid matrix.

Q: Histologically, Deep (aggressive) angiomyxoma is a paucicellular neoplasm composed of bland spindle cells in a myxoid matrix, prominently featuring blood vessels with [...].
Deep (aggressive) angiomyxoma. Medium-sized to large vessels can be seen, with thickened walls. Note the presence of particularly distinct myoid bundles wrapping around vessels of various calibres.
Deep (aggressive) angiomyxoma. This tumour is characteristically paucicellular and composed of bland spindle cells set within an abundant myxoid matrix interspersed with medium-sized to large vessels.
A: thick, muscular walls
Back Extra: Deep (aggressive) angiomyxoma
- Clinical: Patients typically present with a large and painless mass or ill-defined swelling, most common in women of reproductive age.
- Micro: Characterized by a paucicellular neoplasm with bland spindle cells in a myxoid matrix and prominent blood vessels with thick, muscular walls.
- Ancillary: Rearrangements of the HMGA2 locus (12q14.3) are identified in approximately one third of cases.
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Deep (aggressive) angiomyxoma. This tumour is characteristically paucicellular and composed of bland spindle cells set within an abundant myxoid matrix interspersed with prominent vessels.
Deep (aggressive) angiomyxoma. Medium-sized to large vessels can be seen, with thickened walls. Note the presence of particularly distinct myoid bundles wrapping around vessels of various calibres.
Deep (aggressive) angiomyxoma. This tumour is characteristically paucicellular and composed of bland spindle cells set within an abundant myxoid matrix interspersed with medium-sized to large vessels.
HMGA2 (12q14.3) rearrangement in aggressive angiomyxoma. A Chromosome 12 schematic illustrating the HMGA2 locus and flanking dual-colour FISH probe set. B Break-apart HMGA2 FISH demonstrates the presence of a rearrangement of this locus in tumour interphase nuclei (split red and green signals). C Schematic representation of an HMGA2-YAP1 fusion identified in a case of aggressive angiomyxoma of the vulva, with the junction between exon 3 of HMGA2 and exon 2 of YAP1.

Q: Molecular analysis of Deep (aggressive) angiomyxoma reveals gene rearrangements involving the [...] locus (12q14.3) in approximately one-third of cases.
HMGA2 (12q14.3) rearrangement in aggressive angiomyxoma. A Chromosome 12 schematic illustrating the HMGA2 locus and flanking dual-colour FISH probe set. B Break-apart HMGA2 FISH demonstrates the presence of a rearrangement of this locus in tumour interphase nuclei (split red and green signals). C Schematic representation of an HMGA2-YAP1 fusion identified in a case of aggressive angiomyxoma of the vulva, with the junction between exon 3 of HMGA2 and exon 2 of YAP1.
A: HMGA2
Back Extra: Deep (aggressive) angiomyxoma
- Clinical: Patients typically present with a large and painless mass or ill-defined swelling, most common in women of reproductive age.
- Micro: Characterized by a paucicellular neoplasm with bland spindle cells in a myxoid matrix and prominent blood vessels with thick, muscular walls.
- Ancillary: Rearrangements of the HMGA2 locus (12q14.3) are identified in approximately one third of cases.
Reference Gallery:
Deep (aggressive) angiomyxoma. This tumour is characteristically paucicellular and composed of bland spindle cells set within an abundant myxoid matrix interspersed with prominent vessels.
Deep (aggressive) angiomyxoma. Medium-sized to large vessels can be seen, with thickened walls. Note the presence of particularly distinct myoid bundles wrapping around vessels of various calibres.
Deep (aggressive) angiomyxoma. This tumour is characteristically paucicellular and composed of bland spindle cells set within an abundant myxoid matrix interspersed with medium-sized to large vessels.
HMGA2 (12q14.3) rearrangement in aggressive angiomyxoma. A Chromosome 12 schematic illustrating the HMGA2 locus and flanking dual-colour FISH probe set. B Break-apart HMGA2 FISH demonstrates the presence of a rearrangement of this locus in tumour interphase nuclei (split red and green signals). C Schematic representation of an HMGA2-YAP1 fusion identified in a case of aggressive angiomyxoma of the vulva, with the junction between exon 3 of HMGA2 and exon 2 of YAP1.

Q: Histologically, Dermatofibrosarcoma Protuberans is characterized by slender spindle cells arranged in a storiform pattern that infiltrate adipose tissue in a classic [...] pattern.
Dermatofibrosarcoma protuberans. Dermatofibrosarcoma protuberans is composed of slender spindle cells arranged in a storiform pattern that infiltrate adipose tissue in a honeycomb pattern.
A: honeycomb
Back Extra: Dermatofibrosarcoma Protuberans
- Clinical: Dermatofibrosarcoma protuberans (DFSP) typically presents as a slow-growing dermal mass, ranging in size from 0.5 to 15 cm, with a median size of 4 cm.
- Micro: Conventional DFSP is characterized by a storiform pattern of uniform, hyperchromatic spindled cells that infiltrate the subcutis in a lace-like or honeycomb pattern.
- Ancillary: The presence of a COL1A1-PDGFB fusion is diagnostic of DFSP, and the tumour cells are diffusely CD34-positive.
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Dermatofibrosarcoma protuberans. Dermatofibrosarcoma protuberans is composed of slender spindle cells arranged in a storiform pattern that infiltrate adipose tissue in a honeycomb pattern.
Dermatofibrosarcoma protuberans. The tumour cells are diffusely CD34-positive.

Q: The tumor cells in Dermatofibrosarcoma Protuberans (which typically harbor a characteristic COL1A1-PDGFB fusion) exhibit diffuse immunohistochemical positivity for [...].
Dermatofibrosarcoma protuberans. The tumour cells are diffusely CD34-positive.
A: CD34
Back Extra: Dermatofibrosarcoma Protuberans
- Clinical: Dermatofibrosarcoma protuberans (DFSP) typically presents as a slow-growing dermal mass, ranging in size from 0.5 to 15 cm, with a median size of 4 cm.
- Micro: Conventional DFSP is characterized by a storiform pattern of uniform, hyperchromatic spindled cells that infiltrate the subcutis in a lace-like or honeycomb pattern.
- Ancillary: The presence of a COL1A1-PDGFB fusion is diagnostic of DFSP, and the tumour cells are diffusely CD34-positive.
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Dermatofibrosarcoma protuberans. Dermatofibrosarcoma protuberans is composed of slender spindle cells arranged in a storiform pattern that infiltrate adipose tissue in a honeycomb pattern.
Dermatofibrosarcoma protuberans. The tumour cells are diffusely CD34-positive.

Q: Histologically, Solitary Fibrous Tumor of the Lower Genital Tract is composed of haphazardly arranged bland spindle cells within a collagenous stroma, accompanied by a striking [...]-like vascular pattern consisting of branching, staghorn-shaped vessels.
Solitary fibrous tumour. Solitary fibrous tumour is usually composed of bland spindle cells set within a variably collagenous matrix and associated with a striking haemangiopericytoma-like vascular pattern.
A: hemangiopericytoma
Back Extra: Solitary Fibrous Tumour of the Lower Genital Tract
- Clinical: Patients present with a slow-growing mass, and these tumours occur over a wide patient age range (22–75 years), with peak incidence in the fifth decade of life.
- Micro: SFT is characterized by haphazardly arranged spindled to ovoid cells within a variably collagenous stroma, with branching, staghorn-shaped blood vessels.
- Ancillary: NAB2-STAT6 gene fusions are pathognomonic for SFT, and STAT6 immunohistochemistry is a sensitive and specific surrogate for all fusions.
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Solitary fibrous tumour. Solitary fibrous tumour is usually composed of bland spindle cells set within a variably collagenous matrix and associated with a striking haemangiopericytoma-like vascular pattern.

Q: Histologic examination of Angiosarcoma typically reveals a lobulated architecture with closely packed, anastomosing abortive [...] and solid sheets of atypical cells with prominent hemorrhage and necrosis.
Epithelioid angiosarcoma of the vagina. The tumour is composed of atypical epithelioid cells forming irregular vascular channels associated with prominent haemorrhage.
A: vascular channels
Back Extra: Angiosarcoma
- Clinical: Patients with angiosarcoma typically present with vaginal bleeding, anaemia, and nonspecific gastrointestinal symptoms. Vulvar tumours may appear as white papules.
- Micro: Angiosarcoma exhibits a lobulated architecture with closely packed, anastomosing abortive vascular channels, cystic spaces, and solid sheets of spindled and epithelioid cells with haemorrhage and necrosis.
- Ancillary: Tumour cells in angiosarcoma stain positively for CD31, CD34, factor VIII, and ERG. High-level MYC gene amplifications are common in postradiation and chronic lymphoedema-associated secondary angiosarcomas.
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Epithelioid angiosarcoma of the vagina. The tumour is composed of atypical epithelioid cells forming irregular vascular channels associated with prominent haemorrhage.

Q: As seen in the provided vaginal tumor, a notable morphologic variant of Angiosarcoma is composed of atypical [...] cells that form irregular vascular spaces associated with prominent hemorrhage.
Epithelioid angiosarcoma of the vagina. The tumour is composed of atypical epithelioid cells forming irregular vascular channels associated with prominent haemorrhage.
A: epithelioid
Back Extra: Angiosarcoma
- Clinical: Patients with angiosarcoma typically present with vaginal bleeding, anaemia, and nonspecific gastrointestinal symptoms. Vulvar tumours may appear as white papules.
- Micro: Angiosarcoma exhibits a lobulated architecture with closely packed, anastomosing abortive vascular channels, cystic spaces, and solid sheets of spindled and epithelioid cells with haemorrhage and necrosis.
- Ancillary: Tumour cells in angiosarcoma stain positively for CD31, CD34, factor VIII, and ERG. High-level MYC gene amplifications are common in postradiation and chronic lymphoedema-associated secondary angiosarcomas.
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Epithelioid angiosarcoma of the vagina. The tumour is composed of atypical epithelioid cells forming irregular vascular channels associated with prominent haemorrhage.

Q: In proximal-type Epithelioid Sarcoma, the large polygonal cells with abundant eosinophilic cytoplasm frequently exhibit characteristic [...] inclusions.
Proximal-type epithelioid sarcoma. Proximal-type epithelioid sarcoma, the most common form of epithelioid sarcoma in the female genital tract, is composed of sheets of polygonal cells with abundant eosinophilic cytoplasm; rhabdoid inclusions are frequent.
A: rhabdoid
Back Extra: Epithelioid Sarcoma
- Clinical: Epithelioid sarcoma commonly presents as a rapidly growing mass in the vulva, with a peak incidence in the fourth to fifth decade of life.
- Micro: Proximal-type epithelioid sarcoma is characterized by large, polygonal cells with abundant eosinophilic cytoplasm and eccentric nuclei, often showing rhabdoid inclusions.
- Ancillary: Immunohistochemical staining for keratin, EMA, and vimentin is positive, with loss of SMARCB1 (INI1) expression.
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Proximal-type epithelioid sarcoma. Proximal-type epithelioid sarcoma, the most common form of epithelioid sarcoma in the female genital tract, is composed of sheets of polygonal cells with abundant eosinophilic cytoplasm; rhabdoid inclusions are frequent.

Q: The defining immunohistochemical and molecular feature of Epithelioid Sarcoma is the diagnostic loss of [...] expression.
Proximal-type epithelioid sarcoma. Proximal-type epithelioid sarcoma, the most common form of epithelioid sarcoma in the female genital tract, is composed of sheets of polygonal cells with abundant eosinophilic cytoplasm; rhabdoid inclusions are frequent.
A: SMARCB1 (INI1)
Back Extra: Epithelioid Sarcoma
- Clinical: Epithelioid sarcoma commonly presents as a rapidly growing mass in the vulva, with a peak incidence in the fourth to fifth decade of life.
- Micro: Proximal-type epithelioid sarcoma is characterized by large, polygonal cells with abundant eosinophilic cytoplasm and eccentric nuclei, often showing rhabdoid inclusions.
- Ancillary: Immunohistochemical staining for keratin, EMA, and vimentin is positive, with loss of SMARCB1 (INI1) expression.
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Proximal-type epithelioid sarcoma. Proximal-type epithelioid sarcoma, the most common form of epithelioid sarcoma in the female genital tract, is composed of sheets of polygonal cells with abundant eosinophilic cytoplasm; rhabdoid inclusions are frequent.

Q: Histologically, Ewing Sarcoma classically consists of a monotonous population of [...] cells arranged in sheets or solid aggregates, typically with scant eosinophilic cytoplasm and brisk mitotic activity.
Ewing sarcoma. Small round cells with scant eosinophilic cytoplasm and hyperchromatic nuclei form sheets and are associated with brisk mitotic activity.
A: small round
Back Extra: Ewing Sarcoma
- Clinical: A cervical, vaginal, or vulvar mass is the most common presentation in the female genital tract. These are extremely rare lesions that affect premenopausal women, with a median age of 29 years.
- Micro: Tumours consist of a monotonous population of small round cells arranged in sheets or solid aggregates, with brisk mitotic activity and frequent necrosis.
- Ancillary: Immunohistochemically, there is diffuse, strong, membranous CD99 expression and nuclear FLI1 expression. EWSR1 (EWS)-FLI1 fusion is detected in most tumours.
Reference Gallery:
Ewing sarcoma. Small round cells with scant eosinophilic cytoplasm and hyperchromatic nuclei form sheets and are associated with brisk mitotic activity.

Q: Most cases of Ewing Sarcoma are characterized by a defining genetic translocation that results in a fusion between FLI1 and [...].
Ewing sarcoma. Small round cells with scant eosinophilic cytoplasm and hyperchromatic nuclei form sheets and are associated with brisk mitotic activity.
A: EWSR1
Back Extra: Ewing Sarcoma
- Clinical: A cervical, vaginal, or vulvar mass is the most common presentation in the female genital tract. These are extremely rare lesions that affect premenopausal women, with a median age of 29 years.
- Micro: Tumours consist of a monotonous population of small round cells arranged in sheets or solid aggregates, with brisk mitotic activity and frequent necrosis.
- Ancillary: Immunohistochemically, there is diffuse, strong, membranous CD99 expression and nuclear FLI1 expression. EWSR1 (EWS)-FLI1 fusion is detected in most tumours.
Reference Gallery:
Ewing sarcoma. Small round cells with scant eosinophilic cytoplasm and hyperchromatic nuclei form sheets and are associated with brisk mitotic activity.