Anaplastic oligoastrocytoma

Anaplastic oligoastrocytoma, also known as anaplastic mixed glioma or mixed anaplastic oligoastrocytoma, is a rare malignant brain tumor classified as a World Health Organization (WHO) grade III glioma. This tumor contains a mixture of two types of glial cells: oligodendrocytes and astrocytes, both of which display anaplastic (high-grade) features including increased cellularity, nuclear atypia, and elevated mitotic activity. It arises within the central nervous system and can occur in various locations within the brain, most commonly in the cerebral hemispheres, particularly the frontal and temporal lobes. Symptoms depend on the tumor's location and size and may include headaches, seizures, cognitive changes, personality or behavioral alterations, focal neurological deficits such as weakness or speech difficulties, nausea, and vomiting related to increased intracranial pressure. The disease typically presents in adulthood, with a peak incidence in the fourth and fifth decades of life. It is important to note that the 2016 WHO Classification of Tumors of the Central Nervous System discouraged the diagnosis of oligoastrocytoma, and the 2021 WHO classification effectively eliminated this entity, reclassifying most mixed gliomas as either oligodendroglioma or astrocytoma based on molecular markers such as IDH mutation status and 1p/19q codeletion. Treatment historically included maximal safe surgical resection followed by radiation therapy and chemotherapy, often with temozolomide or a PCV regimen (procarbazine, lomustine, and vincristine). Prognosis varies but is generally intermediate between anaplastic astrocytoma and anaplastic oligodendroglioma, with molecular features significantly influencing outcomes. IDH-mutant tumors tend to carry a more favorable prognosis compared to IDH-wildtype tumors.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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