Lung agenesis in a neonate presenting with contralateral mediastinal shift.

A neonate with right lung agenesis presenting with respiratory distress is described. The unusual radiological features were contralateral mediastinal shift (in contrast to expected ipsilateral shift) and diaphragmatic eventration on the affected side. Mediastinal shift to the opposite side was due to intrathoracic hepatic herniation under a high placed eventrated diaphragm. Both these features have not been reported in association with lung agenesis to date. The authors have discussed other causes of respiratory distress in newborns that can cause mediastinal shift and have urged a high degree of clinical suspicion to pick up the cases with lung agenesis. The newer diagnostic modalities and the causes of mortality in neonates with this anomaly have also been highlighted.