Anaplastic Pleomorphic Xanthoastrocytoma: Morphological and Molecular Features of Three Cases

Pleomorphic xanthoastrocytoma (PXA) is usually a low grade astrocytic tumor. However, some cases show significant mitotic activity (5 or more mitosis per 10 High Power Field) and/or necrosis. These tumors are described as pleomorphic xanthoastrocytomas with anaplastic features and display increased risk of recurrence. We aimed to evaluate histopathological, immunohistochemical and molecular features of PXAs with anaplastic features, by reporting three primary cases displaying recurrence. Histopathologically we observed rhabdoid-like monomorphic atypical tumoral cells with increased mitotic activity, vascular endothelial proliferation and necrosis. Immunohistochemically, astrocytic and neuronal components displayed different specific staining properties. In 2 cases p53 was immunopositive. We detected BRAF V600E mutation in 2 cases and p16 mutation in one case, by fluorescence in situ hybridization (FISH) method. Anaplastic pleomorphic xanthoastrocytoma (APXA) is a rare tumor. We have presented 3 primary APXA cases displaying all characteristic histopathological features. Two of these cases were immunopositive for p53. Therefore, we think that this marker may not be so useful in differentiating APXA from glioblastoma (GBM). Two of our three cases display BRAF V600E mutation, which is compatible with the literature.