Single, mediastinal, unilobar lung--a rare form of subtotal pulmonary agenesis.

We describe a case of a full-term infant with severe respiratory failure and pulmonary insufficiency caused by an anomaly consisting of a single, unilobar lung arising from the trachea and situated in the middle mediastinum. Plain film, echocardiogram, and surgical aspects will be described and correlated with the post mortem findings and embryologic considerations. We were unable to find a similar case reported in the literature and conclude that this rare lesion represent an intermediate form between total and unilateral pulmonary agenesis.