Malignant transformation of a benign oncocytoma of the submandibular gland: a case report.

Oncocytic carcinoma arising in the submandibular gland is an extremely rare tumor and only 11 cases have been reported previously. We report on a 51-year-old man with a previously benign oncocytoma in the submandibular gland that transformed from a benign morphology to malignant cellular atypia and mitosis. To our knowledge, the current report is the first published case of a malignant transformation from benign oncocytoma to oncocytic carcinoma of the submandibular gland. The proliferative activity of the tumor cells was evaluated immunohistochemically using antibodies against Ki-67.