IDH1 and astrocytoma (excluding glioblastoma): All IDH-mut diffuse astrocytic tumors have been considered as a single disease entity (astrocytoma, IDH-mut), graded (2, 3, or 4) based on the presence not only of microvascular proliferation or necrosis but also of other molecular markers with negative prognostic value, such as CDKN2A/B homozygous deletion.