Unilateral absence of a pulmonary artery: congenital disease or embolic occlusion?

A young man with congenital absence of the left pulmonary artery is reported. A right aortic arch and normal pulmonary pressures essentially rule out an alternate diagnosis of occlusive chronic thrombus in the central pulmonary arteries. Recurrent or massive haemoptysis makes an exact knowledge of the pulmonary circulation advisable.