A case of congenital lobar emphysema

A two month old boy was admitted to the paediatric ward of the University of Benin Teaching Hospital, Nigeria with tachypnoea and poor suckling from the 4 th hour of life and fever, cough and dyspnoea of two weeks duration. There was no grunting. He was delivered at term via spontaneous vertex delivery in a rural secondary health facility where mother received routine antenatal care. No obstetric ultrasound scan was done. Immediate post partum period was normal. Birth weight was 3.1kg but he gained only 0.7kg over the next 2 months despite exclusive breastfeeding because respiratory distress interfered with suckling. He has received BCG, OPV1&2 and DPT1. Both parents are petty traders with secondary level of education.

The initial diagnosis was bronchopneumonia complicated with a left-sided pneumothorax.Urgent chest radiograph (Figure 1a) showed hyperlucent, hyperinflated left upper lobe with reduced lung markings and collapse of the left lower lobe.There was herniation of the left upper lobe into the mediastinum causing a mediastinal shift to the right.Echocardiography showed no structural anomaly.A planned computerized tomography (CT) scan of the chest was unachieved due to financial constraints.Final diagnosis was congenital lobar emphysema (CLE).He received intravenous antibiotics, supplemental oxygen and other supportive care.He has improved on conservative management and the superimposed acute respiratory infection has resolved.He was planned for a lobectomy.Meanwhile, he is being followed up at the paediatric out-patient department.

Discussion
Congenital lobar emphysema (CLE) is a rare lung malformation that may cause persistent respiratory distress in infants.It is due to hyperinflation of a lung lobe, collapse of adjacent lobe, compression of contralateral normal lung and mediastinal shift 1 .It has a prevalence of 1 in 20,000 to 1 in 30,000 live births and is three times commoner in males 2 .The underlying defect in CLE is often deficiency of bronchial cartilage and airway collapse creating a 'ball-valve' mechanism and air trapping during expiration 1 .However, a definitive causative agent may not be identified in about 50 percent of cases 2 .The left upper lobe is most commonly affected but any lobe can be involved and rarely it is bilateral 1,2 .About a half of cases are symptomatic in the neonatal period and nearly all by six months of age 2,3 .They often present with tachypnoea and dyspnoea but recurrent pneumonia and failure to thrive may complicate the illness 2 .Factors that may enhance the recurrence of severe symptoms in CLE include superimposed respiratory tract infections and coexistence of congenital heart disease 1,3 .
Our patient presented in early infancy with typical features of CLE dating from the early neonatal period.He had progressive respiratory distress that interfered with suckling and led to poor weight gain.Khemiri et al 3 reported progressive respiratory distress in 65% of 17 patients.Chest X ray (CXR) and CT scans showed hyper-aeration of the affected lobes in all cases 3 .Thakral et al reported similar features 2 .We confirmed the diagnosis of CLE in our patient based on the typical clinical and CXR features including the hyper-inflated left upper lobe with cardio-mediastinal shift to the right, creating retrosternal lucency (Figures 1a and 1b).The bulging of the left hemithorax noted in this case is rarely reported 2,3 .This clinical finding is due to the severity of the disease in our patient.
Prenatal diagnosis of CLE can be made with ultrasonography showing hyperechogenicity but in utero surgical management is not recommended 4 .Definitive diagnosis of CLE can be made postnatally from typical CXR findings as in this infant 3,5 .CT of the thorax can delineate the anatomy of the affected lobe by showing stretched, attenuated, spread-out vessels in the emphysematous lobe and compressive atelectasis of other lobes 5 .Differential diagnosis of CLE includes pneumothorax but presence of linear bronchovascular and alveolar markings in CLE differentiates it from pneumothorax which has no lung makings 5,6 .
Conservative management is suitable for mild cases 7 but severely symptomatic cases like ours will benefit from surgical excision of the affected lobe 5,7 .Delayed treatment can result in failure to thrive, atelectasis and pulmonary air leak 2 .However, surgical resection was deferred in this case because the parents could not afford it at present.