Presentation
Seizures followed by decreased level of consciousness and confusion three hours ago. No sensory or motor deficit.
Patient Data
Ill-defined hypo-density predominantly affecting the sub cortical white matter of the right posterior frontal lobe. Mildly effaced adjacent cortical sulci; otherwise, no gross mass effect, hydrocephalus or mid line shift is seen. No calcifications or hemorrhage is seen in the lesion. Conclusion: Ill-defined sub cortical white matter hypo-density in the right posterior frontal lobe. Possible differential diagnosis includes encephalitis & venous infarction; however, the possibility of a space occupying lesion also cannot be excluded.
Focal T2 hyper intensity measuring about 4.5 x 4.0 cm, with surrounding vasogenic edema, seen in the sub cortical right posterior frontal lobe. A small focus of bleed is seen within it on SWI. No significant diffusion restriction is seen. Minimal enhancement is seen in the lesion on the post contrast study. MR spectroscopy shows increased lactate & lipid levels, reduced NAA peak and high choline peak. Impression: Focal lesion in the right posterior frontal lobe, with MRI & MRS features, suggestive of a neoplastic lesion.
Case Discussion
The patient went on to have a right craniotomy and right frontal lobe lesion resection.
Histology:
By immunohistochemical stains, the neoplastic cells are positive for Olig2 while negative for IDH1 and GFAP. ATRX shows retained nuclear staining and P53 shows a wild-type pattern. Ki-67=5%.
1p/19q co-deletion detected by FISH.
IDH2 c.515G>A (p.R172K): Positive mutation on Solid Tumor NGS Panel (52 genes).
Final diagnosis:
oligodendroglioma, IDH-mutant and 1p/19q co-deleted (WHO grade II)