[A rare and little known cause of cyanosis: pulmonary arteriovenous aneurysm].

Cyanosis with digital clubbing and a systolic murmur were found in a five and a half-year-old. The usual causes of cyanosis, including congenital heart disease, were discussed. Correct diagnosis was, however, arteriovenous aneurysm of the lung which was seen on the pulmonary angiogram. The lung density on chest films and lack of echocardiographic evidence of congenital heart disease might have suggested this infrequent malformation. Permanent cure was achieved by removing the lower and middle lobes of the right lung.