Observations on the ultrastructure of a bronchial adenoma (carcinoid‐type)

Electron microscopic study of a bronchial adenoma (carcinoid type) demonstrated secretory granules resembling those of the normal and neoplastic argentaffine cell. Histologic demonstration of argentaffine granules within bronchial adenomas of the carcinoid type is difficult. They are readily shown by electron microscopy. This finding augments the existing evidence relating to the endocrine nature of these neoplasms.