Oligodendroglioma

Case contributed by Frank Gaillard
Diagnosis certain

Presentation

Seizures.

Patient Data

Age: 30 years
Gender: Female
mri

Large predominantly cortically based lesion within the left cingulate gyrus, with marked cortical expansion demonstrating homogeneous T1 hypointensity to grey matter and high T2/FLAIR signal. The lesion demonstrates facilitated diffusion, with no contrast enhancement or elevated CBV on perfusion imaging. MR spectroscopy demonstrates elevation of the choline/creatine ratio, with depression of the NAA peak.

There is associated mass effect with rightward deviation of the falx, effacement of the third and left lateral ventricles. The corpus callosum is depressed, with scalloping of its superior margin.

No hydrocephalus.

Conclusion: Features most likely represent a low-grade infiltrative oligodendroglioma or astrocytoma, with no features to suggest high-grade component.

Case Discussion

The patient went on to have a biopsy.

Histology

Sections show cores of brain tissue containing a moderately cellular glial tumor. The tumor cells have enlarged, angulated, moderately pleomorphic nuclei, and are set in a fibrillary background. There are no areas of oligodendroglial morphology.  There is perineuronal satellitosis.  Mitoses are not identified.  There is no microvascular proliferation or necrosis.

IMMUNOHISTOCHEMISTRY

  • GFAP:  positive
  • IDH1 R132H: positive (mutated)
  • ATRX: positive (not mutated)
  • p53: negative
  • p16: negative
  • Ki67: 1-2%

NEXT-GENERATION SEQUENCING GLIOMA GENE PANEL RESULTS:

  • 1p/19q codeletion: DETECTED
  • EGFR amplification: Not detected
  • IDH1 codon 132: PATHOGENIC VARIANT DETECTED (R132H)
  • IDH2 codon 172: No pathogenic variant detected
  • BRAF codon 600: No pathogenic variant detected
  • H3F3A codons 27 and 34: No pathogenic variant detected
  • TERT promoter Chr 5: 1295228 (C228T) and chr5:1295250 (C250T): PATHOGENIC VARIANT DETECTED (C228T)

FINAL INTEGRATED DIAGNOSIS: Oligodendroglioma, IDH-mutant and 1p/19q-codeleted (WHO grade II).

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