IDH1 and astrocytoma (excluding glioblastoma): LGG includes three histological types: astrocytoma, oligodendroglioma, and oligoastrocytoma (4–6), while oligoastrocytoma is no longer considered as a separate entity since the current WHO classification has included molecular markers (including IDH1 mutation and 1p/19q codeletion) to identify astrocytoma and oligodendroglioma, not oligoastrocytoma (3, 7).