Oligodendroglioma, IDH-mutant and 1p/19q-codeleted

• Low-grade IDH-mutant gliomas: from standard post-surgical treatments to novel IDH inhibitors
• Unlocking new horizons: advances in treating IDH-mutant, 1p/19q-codeleted oligodendrogliomas
• Identification of intrinsic imaging subtypes using clustering analysis based on dynamic contrast-enhanced magnetic resonance imaging radiomics features for gliomas: preliminary associations with gene expression profiles
• Early postoperative seizures in patients with adult-type diffuse gliomas: Incidence, risk factors, and clinical outcomes
• Characteristics, outcome, and prognostic factors of young patients with central nervous system World Health Organization grade 3 oligodendrogliomas IDH-mutant and 1p/19q codeleted: A French POLA network study
• α-synuclein expression in glioblastoma restores tumor suppressor function and rescues temozolomide drug resistance
• A single-arm phase 2 study of abemaciclib in adult patients with recurrent grade 3 oligodendroglioma
• The cortical high-flow sign in oligodendroglioma, IDH-mutant and 1p/19q-codeleted is correlated with histological cortical vascular density

Source: WHO Classification of Tumors of the Central Nervous System, 5th Edition (2021)

Definition: Oligodendroglioma, IDH-mutant and 1p/19q-codeleted, is a diffuse glioma defined molecularly by the presence of an IDH1 or IDH2 mutation and a combined whole-arm codeletion of chromosomal arms 1p and 19q. Both alterations are required for diagnosis.

• Type: Diffuse glioma of oligodendroglial lineage
• Molecular markers:
  • IDH1 or IDH2 mutation
  • Whole-arm 1p/19q codeletion
• WHO Grades: 2 or 3
• Typical location: Cerebral hemispheres, most commonly the frontal lobes
• Histopathology:
  • Round, uniform nuclei with perinuclear clearing (“fried egg” appearance)
  • Delicate, branching capillary network (“chicken wire” vasculature)
  • Calcifications common
• Imaging: Often well-demarcated lesion with calcifications on CT or MRI
• Prognosis: Favorable compared to IDH-mutant astrocytomas; sensitive to chemotherapy and radiotherapy

1. Diffuse glioma histology
2. Confirmed IDH1/IDH2 mutation (by sequencing or immunohistochemistry)
3. Codeletion of 1p and 19q (typically via FISH, PCR-based LOH analysis, or DNA methylation profiling)
4. No ATRX loss (ATRX retained)
5. No TP53 overexpression

see Oligodendroglioma treatment

• Without 1p/19q codeletion, the tumor should be classified as an astrocytoma (if IDH-mutant) or glioblastoma (if IDH-wildtype).
• 1p/19q codeletion is associated with better prognosis and increased treatment responsiveness.