Glioblastoma lacking necrosis or vascular proliferations: Different clinical presentation but similar outcome, regardless of histology or isolated TERT promoter mutation

In the 2021 revised World Health Organization Classification of Central Nervous System Tumours (WHO CNS5) classification, isocitrate dehydrogenase 1/2 -wild-type (IDHwt) gliomas lacking necrosis and/or vascular proliferations, but with a TERT-promotor (TERTp) mutation, and/or EGFR amplification, and/or combined gain of chromosome 7 and loss of chromosome 10 (7+/10−), are now classified as IDHwt glioblastoma.1 These formerly labeled "diffuse astrocytomas, IDH wild-type, with genetic features of glioblastoma" are not separated anymore from histologically defined glioblastomas. However, there is still discussion if these gliomas are truly the same in terms of first presentation and survival.2 In 2021, a French series concluded that glioblastoma patients with histology lacking high-grade features have a favorable outcome, with a median overall survival (OS) of 88 months in cases lacking anaplasia, increased mitotic activity, necrosis, or vascular proliferations when only a TERTp mutation is present.3 This challenges the concept of the proposed CNS5 classification of glioblastoma. Therefore, we expanded and re-analyzed a previously published cohort of 71 glioblastoma patients that lacked high-grade features in the original histopathological diagnosis and also showed imaging features that are more compatible with a lower-grade glioma.4,5 To investigate if histological grading had impact on OS in glioblastoma, we reevaluated the histological grade by 2 independent reviewers. We assessed OS for the different histological grades and also specifically investigated the OS impact of isolated TERTp mutations. © The Author(s) 2023.