Bronchial carcinoid tumors.

Twenty-eight pulmonary carcinoid tumors were reviewed histologically and clinically. Hematoxylin-and-eosin-stained sections were utilized, as well as special stains, including the argyrophil and argentaffin reactions. The 22 tumors located centrally, at the level of primary or segmental bronchi, had a microscopic appearance distinct from those located more peripherally. One peripheral tumor that was large in size appeared much more aggressive histologically, and was designated an atypical carcinoid. The origin of carcinoid tumors from Kulchitsky cells in the lung, the distinction of peripheral tumors from chemodectomas, and the relationship of bronchial carcinoids to bronchial epithelial hyperplasias and oat cell carcinomas are discussed.