Fig. 1.

Astrocytoma grading based on genetic alterations according to WHO CNS5 2021. Cyclin-dependent kinase inhibitor 2A (CDKN2A) homozygous deletion, in IDH-mutant astrocytomas, is a marker of the highest malignancy grade. In IDH-wildtype diffuse astrocytic gliomas, the presence of one or more of three genetic parameters (EGFR gene amplification, TERT promoter pathogenic variants, or a combination of chromosome 7 gain and 10 loss [+ 7/− 10]) obligate to assign the highest CNS WHO grade and classify them as glioblastoma. Glioblastoma, IDH-mutant, does not exist in the current classification. WHO CNS5 2021 the fifth edition of the WHO Classification of Tumors of the Central Nervous System, TERT human telomerase reverse transcriptase, WHO World Health Organization