The detection of inconsistent mitotic activity allowed us to exclude a high-grade tumor; nevertheless, because of the high value of Ki67, unusual for low-grade gliomas, and the contrast enhancement of the lesion, a typical feature of high-grade gliomas, to further discriminate between high- and low-grade tumors we performed an analysis of two prognostic negative biomarkers implemented in the new classification of tumors of the central nervous system [33]: TERT promoter mutations and CDKN2A/B gene deletion. The gene discussed is CDKN2A; the disease is glioma.