[Massive hemoptysis caused by disruption of a bronchial aneurysm diagnosed by microscopic examination of the resected lung].

A 29-year-old woman in the 6th month of pregnancy was admitted to our hospital because of repeated hemoptysis after an acute respiratory infection. Fiberoptic bronchoscopy revealed a polypoid lesion at the orifice of the right B3 bronchus and bleeding around the lesion. Bronchial arteriography showed no abnormalities. Transcatheter embolization was unsuccessful. Therefore, a right upper lobectomy was done. Microscopical examination showed a mass of coagulated blood on the mucosal surface of the wall of the B3 bronchus, and a bronchial artery running toward the mucosal surface was seen underneath. The mass was thought to be the polypoid lesion seen during bronchoscopy. Serial sections showed a bronchial aneurysm 1 mm in diameter that had ruptured into the bronchial lumen. Several bronchial arteries were located in the propria mucosa in other bronchial segments, as observed in the B3 bronchus, but no other focus of bleeding was identified. Some cases of hemoptysis of unknown cause may result from similar histological alterations.