An IDH-mutant, 1p/19q co-deleted lower-grade glioma in the frontal lobe of a 40-year-old is WHO grade 2 oligodendroglioma. The classic 'fried egg' artifact appearance of oligodendrocytes on formalin-fixed tissue is due to:
- A Lipid vacuolization representing active myelin synthesis
- B Cytoplasmic swelling and perinuclear halo from formalin fixation artifact ✓
- C Nuclear enlargement from IDH mutation causing 2-hydroxyglutarate accumulation
- D Glycogen accumulation in oligodendrocyte cytoplasm
Explanation
The 'fried egg' or honeycomb appearance of oligodendroglioma cells — round nucleus with a clear perinuclear halo surrounded by a sharp cytoplasmic membrane — is a fixation artifact caused by formalin fixation. During fixation, the delicate oligodendroglial cytoplasm swells and the perinuclear space expands. This artifact is less prominent in frozen sections. IDH1/2 mutations produce 2-hydroxyglutarate (oncometabolite that inhibits alpha-KG-dependent dioxygenases, causing epigenetic dysregulation) but do not cause the perinuclear halo artifact. 1p/19q co-deletion is a defining molecular marker of oligodendroglioma.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.