Oncocytic carcinoid of the lung. An ultrastructural observation.

A case of a 55-year-old female patient with an oncocytic variety of carcinoid tumor of the lung is reported. Electron microscopic observation of marked hyperplasia and increase in number of mitochondria in the tumor cells suggested it to be of oncocytic variety and membrane bound electron dense granules were characteristically found in the tumor cells which were histologically diagnosed as carcinoid.