Disseminated bombesin-producing carcinoid tumor of pulmonary origin.

A case of a bombesin-producing carcinoid tumor of the lung is reported. Morphologically, the tumor was a typical argentaffinic carcinoid which contained bombesin as demonstrated by diffuse granular cytoplasmic staining using the immunoperoxidase method. Electron microscopy revealed dense-core granules measuring 100-150 nm, consistent with bombesin-containing endocrine cells. In man, bombesin-producing endocrine cells are found predominantly in the bronchopulmonary tree and scattered throughout the intestinal tract. The majority of previously reported bombesin-producing tumors have arisen, as in this case, in the lung; thus the demonstration of bombesin-like immunoreactivity in a widely metastatic tumor should direct the search for a primary lesion to the lung. Bombesin is known to have gastrin-releasing hormone activity. The presence of a gastric ulcer in the present patient raised the possibility of a bombesin-mediated Zollinger-Ellison-like syndrome, an association not previously described.