Cerebral malignant tumors with ependymal and choroidal differentiation in two siblings.

Two siblings in a family without a history of phacomatosis or cerebral tumors developed malignant tumors in the posterior fossa at age 28 months and in the left cerebral hemisphere at age 15 months, respectively. Dual ependymal and choroid plexus epithelium differentiation was established by histological, ultrastructural, and immunocytochemical studies. The development of this rare tumor in siblings suggests an inherited predisposition, a common environmental insult, or both.