Supratentorial multifocal gliomas associated with Ollier disease harboring IDH1 R132H mutation: A case report

Somatic mosaicism of isocitrate dehydrogenase 1/2 ( IDH1/2 ) mutation is a cause of Ollier disease (OD), characterized by multiple enchondromatosis. A 35‐year‐old woman who was diagnosed with OD at age 24 underwent resection surgery for multifocal tumors located at the right and left frontal lobes that were discovered incidentally. No apparent spatial connection was observed on preoperative magnetic resonance imaging. Pathological examinations revealed tumor cells with a perinuclear halo in the left frontal lobe tumor, whereas astrocytic tumor cells were observed in the right frontal lobe tumor. Based on positive IDH1 R132H immunostaining and the result of 1p/19q fluorescent in situ hybridization, pathological diagnoses were IDH mutant and 1p/19q‐codeleted oligodendroglioma in the right frontal lobe tumor and IDH mutant astrocytoma in the left frontal lobe tumor, respectively. The DNA sequencing revealed IDH1 R132H mutation in the peripheral blood sample and frontal lobe tumors. This case suggested that in patients with OD, astrocytoma and oligodendroglioma can co‐occur within the same individual simultaneously, and IDH1 R132H mutation was associated with supratentorial development of gliomas.