Oat cell carcinoma (apudoma) of the esophagus: a case report.

An oat cell carcinoma occurring in the esophagus of a 62-year-old man is described. A strong argyrophilia of the oat cells together with the presence electron microscopically of neurosecretory type granules in their cytoplasm suggests a derivation of this tumor from the cells of the APUD series, and the tumor is diagnosed as apudoma. An aberrant columnar epithelium on the esophageal surface is presumed to be the source of its origin. A rapid postoperative course of the patient despite a rather circumscribed growth pattern of the primary tumor appears to characterize the clinical aspect of this case. An apparent accumulation of the cases with esophageal apudoma in Japan is discussed.