An oligodendroglioma is a primary brain tumor, meaning it originates in the brain rather than having spread from another location in the body. Most oligodendrogliomas are found in the frontal lobe of the brain, followed by the temporal lobe. They can spread via the cerebrospinal fluid to anywhere in the brain or spine, but they are rarely found outside the central nervous system.
About half the cells in the brain are the all-important neurons, or nerve cells, which carry information between the brain and every other part of the body; the other half are glial cells that protect, support, and supply nutrients to those neurons. The glial tumor known as an oligodendroglioma is named for the glial cells that they resemble, which are called oligodendrocytes.
Types of Oligodendrogliomas
Like other kinds of tumors, oligodendrogliomas are classified according to a system developed by the World Health Organization. This system standardizes communication about tumors and is important for treatment planning and determining an individual’s prognosis. A spine or brain tumor is assigned this grade based on its characteristics, such as its cell type (where it originated), how fast it is growing, and how closely it resembles normal tissue. A neuropathologist may make this determination based on an examination of cells taken during a biopsy by a neurosurgeon. Oligodendrogliomas are classified as either low-grade (grade II) or high-grade (grade III, or anaplastic). Oligodendrogliomas are never classified as grade I.
Grade II oligodendrogliomas are low-grade tumors. This type of brain tumor is slow-growing and can extend and infiltrate into surrounding tissue. Often, because of their slow growth, a grade II oligodendroglioma can be present for years before symptoms appear and a diagnosis is made. The vast majority of grade II oligodendrogliomas, however, will become grade III over time.
Grade III oligodendrogliomas, also known as anaplastic oligodendrogliomas, are fast-growing and cancerous, spreading into nearby tissues. (See more about our Neuro-oncology service.)
What Causes an Oligodendroglioma?
The cause of most oligodendrogliomas is not known with certainty, but development of an oligodendroglioma has been linked to exposure to radiation as well as to certain gene mutations that can be passed down through families. New research into oligodendroglioma has found that some of these central nervous system tumors appear to have an abnormality involving the loss of parts of certain chromosomes. A biomarker test may be done on a biopsy sample to identify these mutations.
Reviewed by Rohan Ramakrishna, MD
Last reviewed/last updated: December 2020
Illustration by Thom Graves, CMI