Pleomorphic xanthoastrocytoma: a developmental glioneuronal tumor with prominent glioproliferative changes.

Pleomorphic xanthoastrocytoma (PXA) is a rare primary brain tumor, which usually involves the superficial cortex in children and young adults. Although PXA is considered an astrocytic tumor, recent studies suggest the presence of neuronal differentiation and an origin from multipotential precursor cells. To clarify the clinicopathological characteristics, which have not been well established due to the rarity of this tumor, eight cases of histologically proven PXA were retrospectively analyzed, paying special attention to immunohistochemical findings and associated cortical dysplasia. Three males and five females of median age 17 years (range, 11-24 years) were enrolled in the study. All patients presented with epilepsy. Tumor sites included the temporal (n = 5), frontal (n = 2), and temporoparietal (n = 1) lobes. 18F-FDG PET (positron emission tomography) showed hypometabolism of PXA. Immunohistochemical study was performed in six cases using various antibodies for glial and neuronal markers. Gross total resection of the PXA was achieved in all cases. The follow-up period ranged from 7 to 14 years except for two recent cases. All patients are doing well with neither radiological nor clinical evidence of recurrence. The surgical treatment rendered all patients seizure free. The three temporal lobe PXAs were associated with cortical dysplasia. In one tumor, clusters of dysmorphic ganglion cells were found. All examined PXAs demonstrated immunoreactivity for both neuronal and glial markers in the various tumor cells. The immunohistochemical studies undertaken as a part of this study support the proposed astrocytic and neuronal differentiation of PXA, and indicate that PXA is probably a developmental neuroglial tumor with prominent glioproliferative changes associated with focal cortical dysplasia. Cortical dysplasia may be a cause of persistent epilepsy even after complete surgical excision of PXA.