Histopathologic assessment of the first extracerebral manifestation (right temporal skull; Fig. 3) also showed GFAP-positive, IDH1-negative tissue with preserved ATRX expression and H3 trimethylation and a Ki67/MIB1 index of 53%, confirming the diagnosis of extracerebral GBM. This evidence concerns the gene IDH1 and glioblastoma.