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  • Updated 12.29.2023
  • Released 02.07.2022
  • Expires For CME 12.29.2026

Overview of neuropathology updates for infiltrating gliomas



The most recent edition of the World Health Organization Classification of Tumours of the Central Nervous System (WHO CNS-5), in conjunction with a presentation of histological and immunohistochemical tumor characteristics, features substantial advances in the role of molecular diagnostics in the classification of CNS tumors (25; 19). Updated diagnostic criteria, including the most commonly altered gene and molecular profiles of adult- and pediatric-type diffuse gliomas, are discussed in this article.

Key points

• Glioblastoma is now defined as an infiltrating (diffuse) astrocytic glioma with no mutations in IDH1/2 genes nor histone H3 genes, histologically characterized by microvascular proliferation, necrosis, or molecular features, including TERT promoter mutation, EGFR gene amplification, and +7/-10 chromosome.

IDH-mutant astrocytomas are graded 2-4. IDH-mutant WHO grade 4 was previously referred to as IDH-mutant glioblastoma.

• Homozygous deletion of CDKN2A/B is a molecular signature of WHO grade 4 in IDH-mutant astrocytomas.

• Diffuse hemispheric glioma H3 G34-mutant and diffuse midline glioma H3 K27-altered are distinct gliomas corresponding to WHO grade 4.

• In children and young adults, subtypes of IDH‐wildtype or H3‐wildtype diffuse gliomas have distinct clinical features in the setting of a BRAF V600E mutation, FGFR1 alteration, other MAPK pathway alteration, or an MYB or MYBL1 rearrangement.

• Glioblastoma is no longer used in the setting of a pediatric-type neoplasm.

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ISSN: 2831-9125