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A lesion of increased signal intensity on the T2 and associated with positive mass effect lies in the postcentral gyrus of the parietal lobe and extends down to involve the superior temporal lobe on the left. The lesion is of heterogeneous signal intensity. No restricted diffusion. No contrast enhancement.
Conclusion: Features suggest a glioma of the left parietal lobe. The lack of contrast enhancement is in keeping with a low-grade tumor. Lack of T2-FLAIR mismatch and extensive cortical involvement raises the possibility of an oligodendroglioma.
The patient went on to have a resection.
Sections show a hypercellular tumor composed of moderately pleomorphic cells containing round to oval, hyperchromatic, vesicular nuclei with conspicuous nucleoli and prominent perinuclear clearing. Tumor cells are arranged in diffuse sheets intersected by thin-walled "chicken-wire" capillaries. Occasional mitotic figures are identified (up to 2/10hpf). Tumor cells demonstrate prominent secondary structuring. No necrosis or microvascular proliferation is seen.
- GFAP: Positive
- NogoA: Positive
- Nestin: Positive (low)
- IDH-1 R132H: Positive (mutated)
- ATRX: Positive (non-mutated)
- p53: Negative
- p16: Positive
- Topoisomerase labeling index: 8%
- Chromosome 1 Mean copies 1p per cell: 1.18 Mean copies 1q per cell: 1.95 1p/1q ratio: 0.61
- Chromosome 19 Mean copies 19q per cell: 1.47 Mean copies 19p per cell: 2.48 (polysomy present) 19q/19p ratio: 0.59
FISH summary: 1p/19q co-deletion detected.
FINAL DIAGNOSIS: Oligodendroglioma, IDH mutant, chromosome 1p/19q co-deleted (WHO Grade II).