Significance of perilesional T1 hyperintense areas in the differential diagnosis of primary adult-type diffuse glioma: A case report.

Perilesional T1 hyperintensity on magnetic resonance imaging (MRI) of intra-axial brain masses is an unusual feature of the perilesional area, characteristic of cavernous malformations (CMs) and metastatic brain tumors (METs). Here, we report a case of primary diffuse glioma with a perilesional T1 hyperintense area (HIA) on MRI. A 61-year-old woman with transient aphasia visited our hospital. Radiological examination revealed an intra-axial mass with acute/subacute hemorrhaging and calcification in the left frontal lobe. It was presumed to be a CM because of the perilesional T1 HIA. Gross total resection of the tumor was performed, and the pathological diagnosis was anaplastic oligodendroglioma, not otherwise specified by World Health Organization 2016 classification. Histopathological findings in the perilesional T1 HIA indicated hemorrhage involvement in the surrounding white matter. No recurrence appeared after radio-chemotherapy. Perilesional T1 HIAs, characteristic of CMs and METs, are also seen in primary diffuse gliomas. Therefore, caution should be taken when using this sign for the differential diagnosis of intracranial masses.