GFAP and neoplasm: Further tumor characterization was performed (on block 2B): ATRX staining showed retained nuclear expression (Fig. 1B); Ki67 highlighted an overall increased (60%) proliferation rate (Fig. 1C); IDH1-R132H mutation stained negative by IHC (Fig. 1D), whereas GFAP and synaptophysin were positive by IHC; 19q and 1p deletion testing was negative by FISH; H3F3A-K27M mutation was negative by IHC; and MGMT gene promoter methylation was undetected by methylation-specific polymerase chain reaction (PCR) (data not shown).