Grade II oligodendroglioma localized to the corpus callosum.

The presence of a primary central nervous system (CNS) neoplasm within the corpus callosum generally portends a grave prognosis. Common pathologies encountered include glioblastomas and primary CNS lymphomas. In contrast, World Health Organization grade II oligodendroglial tumors demonstrating loss of heterozygosity at 1p and 19q are generally less aggressive, often responding favorably to chemotherapy. The authors present a case of a primary brain tumor isolated to the corpus callosum diagnosed as a grade II oligodendroglioma. A 52-year-old woman presented with new-onset generalized seizure. Magnetic resonance imaging (MRI) revealed a non-contrast-enhancing lesion with associated edema and regional mass effect. The patient underwent a craniotomy and subtotal resection of the lesion using an endoscopic port. Pathological examination revealed a grade II oligodendroglioma. Molecular analysis identified 1p and 19q deletion as well as MGMT promoter methylation. The patient subsequently underwent adjuvant radiation therapy with an excellent response. We present, to our knowledge, the first report of a grade II oligodendroglioma isolated within the corpus callosum with the characteristic molecular features of this tumor type. Histopathologic diagnosis is essential to appropriately guide therapy of callosal tumors.