Glioblastoma multiforme masquerading as a pleomorphic xanthoastrocytoma.

Since its first description by Kepes in 1979, pleomorphic xanthoastrocytoma (PXA) has been considered a tumor with a benign course. Two cases are presented here that support the concept that PXA may be more accurately considered part of a spectrum of astrocytomas that occasionally may act aggressively. These cases represent astrocytomas with PXA components and are characterized by meningeal proximity, a high number of mitoses, and subsequently aggressive clinical behavior. The importance of recognizing the potential of a "benign" PXA to transform into a malignant entity has obvious implications for the therapeutic management of these tumors.