oligodendrogliooma

Oligodendroglioma is a type of glioma that originates from oligodendrocytes in the brain. The term is commonly used for tumors that harbor IDH mutations and codeletion of chromosome arms 1p and 19q. Although sometimes misspelled as oligodendrogliooma, the correct spelling is oligodendroglioma. These tumors typically occur in adults, usually in the fourth to fifth decades, and most often arise in the frontal lobe. They frequently grow slowly and present with seizures, headaches, or cognitive changes.

Diagnosis relies on MRI and, if needed, CT. Imaging may show a calcified mass in the cerebral hemispheres with T2/FLAIR hyperintensity and variable enhancement. The diagnosis is confirmed by histology and molecular testing. Classic histology features include a relatively uniform cell population with clear perinuclear cytoplasm (fried-egg appearance) and a delicate capillary network.

Molecular classification: according to the WHO CNS5, oligodendroglioma is IDH-mutant with 1p/19q-codeletion, and is graded II or III based on histology. The 1p/19q codeletion and IDH mutation confer a better prognosis and chemosensitivity compared with IDH-wildtype tumors. Age, tumor size, and extent of resection also influence outcome.

Treatment and prognosis: Maximal safe surgical resection followed by radiotherapy and chemotherapy is standard. In codeleted tumors, combined radiotherapy and PCV chemotherapy has been shown to improve survival in clinical trials; temozolomide is used as an alternative. With favorable molecular features, long-term survival is possible, and regular MRI follow-up is required to monitor for progression.