Papillary glioneuronal tumor: a case report and review of the literature.

We report a papillary glioneuronal tumor occurring in the right frontal lobe of a 26-yr-old woman and we review the pertinent literature. Papillary glioneuronal tumor (PGNT) is a rare cerebral neoplasm, identified in approximately 37 cases to date. In 2007, the World Health Organization (WHO) classified the PGNT as a grade I neuronal-glial tumor because of its biphasic neurocytic and glial components and indolent clinical course. Patients commonly present with headaches or seizures, but may be asymptomatic with the mass discovered incidentally upon neuroimaging. Histology demonstrates a pseudopapillary architecture with a single or a pseudostratified layer of glial cells overlying hyalinized vasculature with interpapillary regions of neurocytic or ganglion cells. Peripheral eosinophilic granular bodies, Rosenthal fibers, hemosiderin, and areas of calcification are often noted. The PGNT displays moderate cellularity and is typically devoid of necrosis, microvascular proliferation, and mitoses. Its immunohistochemical profile includes glial fibrillary acidic protein (GFAP)-positive glial cells, synaptophysin-positive interpapillary neurocytes, and MIB-1 labeling in the range of 1-2%.