A 28 year-old woman presented to our clinic with a two month history of dizziness, retro-orbital pain, headache and numbness with paresthesia in the right arm. A brain MRI was performed, revealing two distinct T2/FLAIR hyperintense lesions in the left frontal lobe and left parietal lobe. Both areas were non-enhancing by gadolinium contrast. These tumors were resected in a serial fashion with pathology sent on each specimen.

Internal review of the left parietal tumor revealed a histopathologic diagnosis of a glioblastoma, WHO grade IV with a Ki67 index of 15% and p53 positivity in 40% of cells. The parietal tumor carried the canonical IDH1 mutation R132H with wild type TERT promoter mutation. The frontal tumor exhibited pathology of an oligodendroglioma, WHO grade II with 1p19q co-deletion by chromosomal microarray. Ki67 index was 5-10%. ATRX was retained and the TERT promoter was mutated at C228T. Surprisingly, a different IDH1 mutation at R132S was detected. The MGMT promoter was methylated in both tumors. The patient proceeded to IMRT radiotherapy to each primary resection site with concurrent temozolomide.