Late sequelae of treated pleomorphic xanthoastrocytoma: malignant brain stem astrocytoma occurring 15 years after radiation therapy.

The pleomorphic xanthoastrocytoma (PXA) is a unique astrocytic neoplasm with an unexpectedly favorable prognosis despite striking pleomorphism of the cellular constituents. Although a majority of patients experience extended survival, these tumors may recur and some cases progress to high-grade astrocytoma. Recurrence inevitably involves the anatomic vicinity of the primary tumor. In this report, we describe a malignant brain stem astrocytoma that occurred 15 years after surgery and radiation treatment of a 16-year-old patient who had a temporal lobe PXA. To our knowledge, this is the first reported case of a malignant astrocytoma arising outside the primary anatomic site of a previously treated PXA and likely represents a radiation-induced secondary neoplasm.