A 55-year-old man presents with seizures and a contrast-enhancing ring lesion in the right temporal lobe on MRI. Biopsy shows hypercellular tumor with nuclear atypia, endothelial proliferation, palisading necrosis, and abundant mitoses. Which genetic alteration confers a relatively better prognosis in tumors of this WHO grade?

• A IDH1/IDH2 mutation ✓
• B EGFR amplification
• C PTEN deletion
• D TERT promoter mutation alone

Explanation

The biopsy findings describe glioblastoma (WHO grade 4 diffuse glioma). IDH1 or IDH2 mutations are associated with significantly better prognosis in high-grade gliomas compared to IDH-wildtype glioblastoma, with longer overall survival. IDH-mutant glioblastomas tend to arise from lower-grade precursors in younger patients. EGFR amplification and PTEN deletion are common in IDH-wildtype (primary) glioblastoma and are associated with poor prognosis.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.