The classification and diagnostic criteria of tumors of the CNS, published by the World Health Organization (WHO) in 2021, state that molecular signatures such as isocitrate dehydrogenase (IDH) mutational status, epidermal growth factor receptor (EGFR) gene amplification, telomerase reverse transcriptase (TERT) promoter mutation, and duplications and deletions occurring in chromosomes 7 and 10 need to be associated with specific histological and immunohistochemical features for a correct diagnosis of GBM [2]. This evidence concerns the gene TERT and glioblastoma.