oligodendrogliomas

Oligodendroglioma is a type of diffuse glioma that arises from oligodendrocytes in the central nervous system. In modern classification, these tumors are defined by the presence of an IDH mutation and a concurrent co-deletion of chromosome arms 1p and 19q. They are typically categorized as WHO grade II or III, corresponding to low- and higher-grade lesions, with higher-grade tumors showing more rapid progression. The histologic appearance often includes tumor cells with a “fried-egg” shape and a delicate capillary network described as a chicken-wire pattern; calcifications are common.

Epidemiology and clinical presentation: Oligodendrogliomas most commonly affect adults in middle life, with a slight male predominance. Seizures are the most frequent presenting symptom, followed by progressive headaches, cognitive changes, or focal neurological deficits. They are less common in children.

Imaging and diagnosis: Magnetic resonance imaging usually shows a cortical or subcortical, often calcified, T2-hyperintense mass. Imaging features, together with molecular testing for IDH mutation and 1p/19q codeletion, are essential for diagnosis under current guidelines. Histology and molecular profile together determine the diagnostic category.

Treatment and prognosis: Management usually begins with maximal safe surgical resection. Adjuvant radiotherapy is commonly used, especially for higher-grade tumors, often in combination with chemotherapy. The PCV regimen (procarbazine, lomustine, vincristine) is a standard chemotherapy approach, though temozolomide is used when PCV is unsuitable. Tumors with 1p/19q codeletion and IDH mutation generally have a more favorable prognosis and respond better to therapy than non-codeleted tumors. Prognosis depends on grade, extent of resection, molecular features, and treatment response, with longer survival typically observed in codeleted, IDH-mutant oligodendrogliomas compared with other diffuse gliomas. Regular imaging and clinical follow-up are required to monitor for recurrence.