Congenital lobar emphysema

Clinical History

A 5-week-old baby boy presented with respiratory distress. On examination he was found to be tachypneic. Clinically, his chest was clear. CXR showed a hyperinflated and hyperlucent left upper lobe with a mediastinal shift to the right. CT scans confirmed an overinflated left upper lobe and a mediastinal shift. There was no soft tissue mass or cystic change in the affected lobe.

Imaging Findings

A five-week-old baby boy presented with respiratory distress. He was a term baby with normal antenatal ultrasound scans. On examination, he was found to be tachypneic, oxygen saturations 100% on air, and his chest was clear. His blood test reports were also found to be normal. CXR showed a hyperinflated and hyperlucent left upper lobe with a mediastinal shift to the right. A differential diagnosis of congenital lobar emphysema (CLE) or congenital cystic adenomatoid malformation (CCAM) were made. CT confirmed an overinflated left upper lobe and a mediastinal shift in keeping with CLE. There was no soft tissue mass or cystic change observed in the affected lobe. His echocardiogram showed a small muscular VSD. The infant was treated with left upper lobectomy because of respiratory distress and failure to thrive.

Discussion

CLE is a congenital over-expansion of one or more pulmonary lobes. The basic defect is thought to be due to bronchial obstruction acting as a ball valve, resulting in distal air trapping. The causes include intrinsic weakness of the airway wall and extrinsic compression (from pulmonary vessels, lymph nodes, bronchogenic cysts). There is no detectable cause in 50% of cases. CLE occurs rarely (1 in 30,000 births) with an incidence similar to that of congenital cystic adenomatoid malformation and pulmonary sequestration. It affects males three times more often than it affects females. It is associated not only with congenital heart disease, particularly VSD and PDA, but also with Tetralogy of Fallot. CLE usually presents in neonates with respiratory distress and cyanosis. Although initially asymptomatic, respiratory distress develops over days or weeks. Presentation of CLE over the age of 6 months is rare. On CXR, they typically appear as a hyperlucent expanded lobe with air trapping, a contralateral mediastinal shift and compression/collapse of adjacent lobes. In the first few days of life, lobe that is involved can appear as a radio-opaque mass on CXR because of a delayed resorption of fetal fluid. The CXR is usually sufficient to diagnose CLE, but pneumothorax and CCAM can be similar in appearance. CT demonstrates an enlarged and hypo-attenuating affected lobe and may also demonstrate an underlying cause such as an extrabronchial obstructing lesion. Unlike CCAM, there is no soft tissue mass or cystic change in the affected lobe. CLE affects the upper lobes in two-thirds of cases. LUL>RML>RUL. Involvement of the lower lobes or of both lungs is rare. Echocardiography is recommended as part of the workup because of its association with congenital heart disease. The treatment concerns lobectomy, in cases where there is severe respiratory distress or failure to thrive. The majority of less severely affected infants can be treated conservatively and usually show spontaneous improvement over time.

Differential Diagnosis List

Final Diagnosis

Congenital lobar emphysema.

URL:	https://eurorad.org/case/3183
DOI:	10.1594/EURORAD/CASE.3183
ISSN:	1563-4086