Oligodendrogliomas come from oligodendrocytes, one of the types of cells that make up the supportive, or glial, tissue of the brain. They can be low-grade (grade II) or high-grade (grade III, or anaplastic). Oligodendrogliomas are generally soft, grayish-pink tumors. They often contain mineral deposits (called calcifications), areas of hemorrhage, and/or cysts. Under the microscope, these tumor cells appear to have “short arms,” or a fried-egg shape. Sometimes oligodendrogliomas are mixed with other cell types.
These tumors can be found anywhere within the cerebral hemisphere of the brain, although the frontal and temporal lobes are the most common locations.
Because of their generally slow growth, oligodendrogliomas are often present for years before they are diagnosed. The most common symptoms are seizures, headaches, and personality changes. Other symptoms vary by location and size of the tumor.
Tumors of the frontal lobe may cause weakness on one side of the body, personality or behavior changes, and difficulty with short-term memory. Temporal lobe tumors are usually “silent,” causing few symptoms other than perhaps seizures or language problems.
If the tumor is accessible, standard treatment for oligodendroglioma is surgical removal of as much of the tumor tissue as possible. Biopsy is typically performed on tumors that are not accessible to confirm the diagnosis and determine the grade of tumor. Recurrent low-grade oligodendrogliomas can be treated with surgery, radiation therapy (if not given initially), and chemotherapy.
- Grade II Oligodendrogliomas: Close follow-up with regular MRI scans is recommended following the successful removal of low-grade oligodendrogliomas. If some of the tumor remains (also called “residual” tumor), radiation treatment is recommended following surgery. The best timing for radiation therapy (ie, immediately or when the tumor appears to be growing again), is currently being studied in clinical trials.
- Grade III Oligodendrogliomas: Anaplastic oligodendroglioma is typically treated with a combination of radiation therapy and chemotherapy. Recurrent anaplastic oligodendroglioma may be treated with surgery and/or chemotherapy.
About 4% of primary brain tumors are oligodendrogliomas, representing about 10-15% of the gliomas. Only 6% of these tumors are found in infants and children. Most oligodendrogliomas occur in adults ages 50-60, and are found in men more often than women.