Sarcomatous proliferation of the vasculature in a subependymoma.

A case of a recurrent posterior fossa subependymoma in a 60-year-old man is reported. In the recurrent tumor, the vasculature had undergone apparent sarcomatous proliferation of the endothelial cells. The bizarre cells expanded and replaced the vessel walls, and stained for Factor VIII-related antigen. The literature on gliosarcomas arising in brain tumors other than high-grade gliomas is reviewed.