Pleomorphic xanthoastrocytoma: report of a case with light and electron microscopy.

A case of pleomorphic xanthoastrocytoma is reported with light and electron microscopic findings. This unusual tumor arose in a 15-year-old male. The tumor consisted predominantly of nests of xanthomatous cells and plump spindle cells surrounded by a prominent reticulin network. There was considerable cellular pleomorphism with abundant bizarre giant cells and multinucleated cells. Occasional mitoses were present. Electron microscopy and immunoperoxidase localization of glial fibrillary acidic protein (GFAP) confirmed the glial nature of the tumor. Recognition of this tumor is important. Despite its "m alignant" appearance, the tumor characteristically has a relatively good prognosis and should not be confused with high-grade gliomas or meningeal sarcomas, which require aggressive therapy.