Lipomatous primitive neuroectodermal tumor with a glioblastoma component: a case report.

A case of extracerebellar lipomatous primitive neuroectodermal tumor (PNET) with glioblastoma multiforme (GBM) areas is reported. A 44-year-old woman who had been on antipsychotic agents for schizophrenia complained of hemiparesis and drowsiness. She deteriorated progressively and died 3 months later. The autopsy revealed a huge, ill-defined tumor located from right basal ganglia to brain stem. Microscopically, the tumor consisted of three distinct components: clusters of small primitive cells consistent with PNET, mature lipoma-like islands, and a GBM-like component. Neuronal differentiation in PNET areas was confirmed by the presence of Homer Wright rosette, synaptophysin-positive fibrillary background, and ultrastructural demonstration of neuritic processes. Lipoma-like areas composed of lipidized cells containing large lipid droplets were intimately intermingled and closely related with PNET areas. Furthermore, GBM areas were, although predominantly located in the brain stem, often blended with the previous two components. This component was characterized by glial fibrillary acid protein immunoreactivity of atypical tumor cells and the presence of necrosis and endothelial proliferation. PNET areas with lipomatous differentiation in the present tumor may suggest the morphological and histogenetic similarity to liponeurocytoma, although the neuronal element in the former was anaplastic. The association with a GBM component makes the present tumor a unique, and, to our knowledge, previously unrecognized lesion.