Oligodendroglioma

Diagnosis:

Suggested by MRI and confirmed by pathology (brain biopsy/resection)

Pathology:

Histology: small round blue nucleus, halo of cytoplasm ‘fried egg or honey comb’ appearance on formalin fixed tissue. Thin walled branching capillaries ‘chicken wire or wishbone’ appearance. Minigemistocytes, perineuronal satellitosis & Microcalcifications may occur. In higher grade; endothelial proliferation, mitosis & necrosis are present.
Immunohistochemistry: GFAP classic cells are negative, minigemistocytes are positive, some cells have a perinuclear rim= gliofibrillary oligodendrocytes. S100 positive. The following are negative: CLA, Cytokeratins, EMA, HMB45.
FISH: deletion of 1q & 19p.

Findings on Investigations:

Involvedment of the frontal lobes or temporal lobes. Rare in spinal cord, brain stem & posterior fossa
CT:

  • hypodense mass, serpentine calcification, cystic areas. Hemorrhage can occur. Usually no oedema. Variable enhancement

MRI:

  • T1: hypointense
  • T2/FLAIR: hyperintense tumor, hypointense calcification. But calcification is easier to see on CT

Treatment:

Oligodendroglioma:
  • Surgical resection
  • Consider Chemotherapy:
    • Procarbazine +Lomustine CCNU+Vincristine PCV if 1p/19q deletion. Increases progression free survival PFS but doesn’t increase overall survival. Toxicity overweighs benefit in grade III.
    • Temozolamide TMZ if 1p/19q codeletion & low grade (200 mg/m2/day for 5 consecutive days, repeated every 28 days).
Mixed Oligoastrocytoma, WHO grade II & grade III:

If grade II:

  • Surgical resection
  • Consider Chemotherapy: Temozolamide TMZ if 1p/19q codeletion (200 mg/m2/day for 5 consecutive days, repeated every 28 days).

If grade III:

  • Surgical resection
  • Consider radiotherapy

Related articles: