Traumatic pulmonary arteriovenous fistula due to shotgun wound to the chest.

Acquired or congenital pulmonary arteriovenous fistulas are rare. The pulmonary arteriovenous fistula may be either acquired or congenital in origin, the latter being much more frequent than the former. The congenital origin usually combines with other vascular anomaly. Acquired origin has been reported in cases of metastatic carcinoma of the thyroid gland, pulmonary schistosomiasis, and long-standing hepatic cirrhosis.