Pleomorphic xanthoastrocytoma as a component of a temporal lobe cystic ganglioglioma: a case report

We report a case of pleomorphic xanthoastrocytoma (PXA) as a component of a ganglioglioma in a 13-year-old Japanese boy. Magnetic resonance imaging showed a large cystic lesion with an enhanced mural nodule of the left temporal lobe. Microscopic examination of the tumor showed that it was composed of two distinct neoplastic components: dysplastic ganglion cells and a PXA. There were gradual transitions between the two neoplastic components, and the PXA constituted the gliomatous component of the ganglioglioma. The PXA component showed spindle-shaped and pleomorphic large cells with lipidized cytoplasm. The tumor cells were surrounded by numerous reticulin fibers. Immunohistochemically, the ganglion cells were negative for glial fibrillary acidic protein (GFAP), but showed positive staining for a 70-kDa neurofilament protein, synaptophysin, and NeuN. In contrast, PXA cells were positive for GFAP but negative for neuronal markers. Our case is therefore histologically classified as ganglioglioma with PXA as the glial component. These results suggested that PXA and ganglioglioma share a common origin and that the combination of PXA-ganglioglioma would be positioned along the spectrum between PXA and ganglioglioma. Alternatively, these results may support the hypothesis that PXA originates from glioneuronal progenitor cells capable of generating astrocytic and neuronal cell types.