Fig. 1.

Immunostaining and molecular analysis patterns in different glioma subtypes. Complete nuclear loss of H3K27me3 in tumor cells with retained staining in endothelial cells in IDH1 Mut 1p/19q codeleted oligodendroglioma (a, b). c Dot-like H3K27me3 staining in negative tumor cell nuclei was considered loss of H3K27me3 expression in IDH1 Mut 1p/19q codeleted oligodendroglioma. Arrows point to retained nuclear staining in endothelial cells and infiltrating lymphocytes (a–c). Retained nuclear H3K27me3 staining was observed in IDH1 Mut astrocytoma (d–f), IDH Wt Astrocytoma (g–i), and IDH Wt GBM (j–l). a–c 40× magnification (Scale bar = 20 μm); d–l 20× magnification (Scale bar = 50 μm). Mosaic plot analysis comparing the correlation between H3K27me3 (m, n) and ATRX immunoreactivity (o) among glioma subclasses. m IDH Mut 1p/19q codeleted oligodendrogliomas showed significantly lower H3K27me3 staining compared with other glioma subtypes. n Significant differential expression of H3K27me3 was seen between IDH1 and IDH2 Mut 1p/19q codeleted oligodendrogliomas. o Retained ATRX staining showing a statistically significant difference between the two IDH Mut glioma lineages. P ≤ 0.05 was considered significant. p–u Mutational analysis patterns among glioma subtypes. IDH1-R132H Mut oligodendroglioma cases showing a single amino acid transition from p arginine to histidine (R132H), q arginine to serine (R132S), and r arginine to leucine (R132L). IDH2-R172 Mut oligodendroglioma cases showing a single amino acid transition from s arginine to lysine (R172K), t arginine to serine (R172S), and u arginine to tryptophan (R172W). v–y Representative FISH images of IDH Mut glioma subtypes. A case of IDH Mut oligodendroglioma showing both 1p (v) and 19q (w) deletion. A case of IDH Mut astrocytoma showing intact 1p (x) and 19q (y). 1p/19q deleted cases show one red signal (target) and two green signals (control). NR nuclear retention, NL nuclear loss, Mut mutated, Wt wild type, GBM glioblastoma