OLIG2 and neoplasm: IHC: Positive for OLIG2, MAP2, and S100, whereas the EGFR-mutant subtype is negative for OLIG2 and positive for GFAP. Positive nuclear staining for the H3 K27M antibody and negative nuclear staining for H3 K27me3 are helpful for the detection of scattered tumor cells amidst infiltrating areas.