Oat-cell carcinoma of the thymus

Abstract
Oat-cell carcinoma of the thymus gland is exceedingly rare as a primary lesion, and only a few cases have been reported. We report a case in which a neoplasm interpreted as an oat-cell carcinoma was intimately associated with and arose in transition from a carcinoid tumor of the thymus. Ultrastructural features of this lesion were unusual compared with previous descriptions of thymic neuroendocrine neoplasms.