The underwent left temporal craniotomy for tumor resection. Intraoperative findings were of a firm, grey colored lesion abutting the left middle cerebral artery and choroid plexus. Frozen pathology was consistent with astrocytoma.
Pathology:
Tissue sections show a pleomorphic astrocytoma that appears to be based in the superficial cortex with increased mitotic activity (focally reaching 5 mitoses per 10 HPF) and palisading necrosis. Focal perivascular orientation of tumor cells is noted. The main portion of the tumor appears compact with a more moderate component of tumor infiltration at the periphery. No definite eosinophilic granular bodies or Rosenthal fibers are present (PAS). Immunostains show the neoplastic cells are positive for BRAF (V600E mutant protein), CD34 (subset), GFAP, S100, and Olig2, but negative for IDH1 (R132H mutant protein). P53 labels scattered cells. ATRX is retained. There is no increase in pericellular reticulin. A Ki67 proliferation index is increased. MGMT studies were positive for MGMT promoter methylation. NGS studies confirmed the presence of a BRAF V600E mutation and suggested possible homozygous deletion of CDKN2A/2B. No mutations were identified in IDH1, IDH2, or the TERT promoter.
Overall, given the morphologic features, elevated mitotic activity, palisading necrosis, and the molecular findings, the findings are most consistent with anaplastic pleomorphic xanthoastrocytoma (WHO grade 3).