Mixed germ cell tumor and hemangioblastoma in the cerebellum: report of a rare coexistence.

We report a case of a cerebellar tumor consisting of a mixed germ cell tumor (GCT) and a hemangioblastoma. A 22-year-old man presented with myoclonus and cerebellar ataxia. Magnetic resonance imaging showed a tumor mass in the left cerebellar hemisphere. The tumor was totally removed, and the histological diagnosis was an undetermined neoplasm. Ten months later, the patient returned with cerebellar hemorrhage at the site of the previous tumor. An emergency craniotomy was performed, and a tumor mass adjacent to the hematoma was resected. Microscopic examination revealed a mixed GCT consisting of a germinoma, choriocarcinoma, and mature teratomatous component. An area of hemangioblastoma was also found in the same tumor mass. A retrospective examination of the histological sample from the first operation indicated a germinoma. A primary GCT of the posterior fossa is very rare, and there are no other reports of the coexistence of a GCT and a hemangioblastoma. A metastatic GCT lesion of extracranial origin should be considered when the intracranial GCT is non-germinomatous and arises in an unusual site. The most probable hypothesis for the histogenesis of this case was a hemangioblastoma complicated by a "tumor-to-tumor" metastatic lesion of testicular GCT with "burnout" of the primary site.