Abstract
Oncocytic carcinoid is a very rare tumor composed of epithelial cells that have abundant eosinophilic granular cytoplasm. Ultrastructurally, this tumor corresponds to mitochondrial hyperplasia. Therefore, the elctronmicroscopic study is an essential for the diagnosis of oncocytic carcinoid. Fechner and Bentinck first described a pulmonary oncocytoma/oncocytic carcinoid with ultrastructural confirmation in 1973. A case of pulmonary oncocytic carcinoid in the fifty year old male was diagnosed by immunohistochemical and elecronmicroscopic study is presented.