IDH1 and oligodendroglioma: While 80.3% (285/355) of GBM cases retained their original histopathological designation, IDH1/2-mutant astrocytoma cases demonstrated substantial diagnostic heterogeneity, with 71.5% (128/179) of cases initially classified as astrocytoma, 25.1% (45/179) of cases as GBM, 1.7% (3/179) of cases as oligodendroglioma, and 1.7% (3/179) of cases as other glioma subtypes (Fig. 2B).