CDKN2A and astrocytoma (excluding glioblastoma): According to WHO 2021, the tumors were reclassified as follows: 20 cases of “astrocytoma, IDH-mutant, grade 2”; 4 cases of “astrocytoma, IDH-mutant, grade 3”; and 7 cases of “astrocytoma, IDH-mutant, grade 4.” Of the 7 cases of astrocytoma, IDH-mutant, grade 4, two cases were classified based on the pathological features (microvascular proliferation and necrosis) and 5 were classified based on the molecular features (CDKN2A/B HD).