[A case of aberrant left pulmonary basal aneurysm arising from the descending aorta].

A 65-year-old man was referred to our hospital because of fever and abnormal shadow in the left lung. An aortogram revealed a large artery arising from the descending aorta supplying the left basal segment and, which then flowed into the pulmonary vein. This artery had an aneurysm and 30 mm in diameter. Bronchography showed compression of the left basal branch. A clinical diagnosis of an aberrant left pulmonary basal aneurysm arising from descending aorta was made, and left lower lobectomy was performed, because of the danger apprehension of the aneurysmal rupture. The procedure was successful. There are only 15 case reports of a systemic artery supplying the lung with normal bronchial branch in Japan. Differences of this anomaly from pulmonary sequestration were discussed.