Pleomorphic xanthoastrocytoma

Definition

A rare astrocytoma characterized by GFAP-expressing cells with nuclear/cytoplasmic pleomorphism, xanthomatous changes, and eosinophilic granular bodies surrounded by a reticulin network. Pleomorphic xanthoastrocytoma (PXA) most often has cerebral hemispheres location with meningeal involvement, mainly affects younger individuals and is frequently characterized by early seizure manifestation. Extent of resection and mitotic index are important prognostic factors. PXA commonly exhibits MAPK signaling pathway genes mutations (most frequently BRAFV600E), often combined with CDKN2A/B homozygous deletion, and a specific DNA methylation profile. The tumor corresponds to WHO grade 2 or grade 3, mainly depending on the mitotic index and Ki-67 expression.