Posterior fossa tumor with distinct choroid plexus papilloma and ependymoma components.

Synchronous occurrence of multiple primary central nervous system (CNS) tumors of different histological types is uncommon in patients without radiation history or genetic syndrome association. We herein report a sporadic case of posterior fossa tumor with synchronous choroid plexus papilloma (CPP) and ependymoma (EP) components. A 7-year-old girl with no significant past or familial medical history presented with 2 years of migraine type headaches. Brain magnetic resonance imaging showed a cystic mass with a mural enhancing nodule centered within the cerebellar vermis. The patient underwent gross total resection of the tumor. Histologic examination showed a tumor with two distinct components. The predominant component demonstrated classic morphological and immunohistochemical characteristics of choroid plexus papilloma CPP, WHO grade I. However, there were a few discrete foci, where tumor cells showed architectural, cytological, and immunohistochemical features characteristic of an ependymoma, WHO grade II. In addition, there was exuberant piloid gliosis secondary to infiltration of the CPP component into the adjacent brain parenchyma. Followup brain imaging at 14 months after surgery showed no evidence of residual or recurrent tumor. To the best of our knowledge, this is the first reported case of synchronous CPP and EP in the posterior fossa.