According to the 2021 WHO Classification of CNS Tumors, a diffuse glioma in a 30-year-old with IDH1 R132H mutation and 1p/19q codeletion is classified as:
- A Astrocytoma, IDH-mutant (grade 2 or 3)
- B Glioblastoma, IDH-mutant
- C Oligodendroglioma, IDH-mutant and 1p/19q-codeleted (WHO grade 2 or 3) ✓
- D Diffuse midline glioma, H3 K27-altered
Correct answer: C. Oligodendroglioma, IDH-mutant and 1p/19q-codeleted (WHO grade 2 or 3)
Explanation
WHO 2021 CNS classification integrates molecular markers as diagnostic criteria. Diffuse gliomas with IDH mutation AND 1p/19q codeletion are definitionally oligodendrogliomas; the 1p/19q codeletion results from an unbalanced translocation and is accompanied by CIC and FUBP1 mutations. IDH-mutant gliomas without 1p/19q codeletion (but with ATRX loss) are astrocytomas. IDH-wildtype diffuse glioma with EGFR amplification, TERT mutation, or +7/−10 is GBM. H3 K27-altered defines diffuse midline glioma.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.