The Facts
A glioma is a type of malignant brain tumor. A malignant tumor is a mass of unneeded and often abnormal cells that is cancerous.
Tumors can develop in any part of the brain or its nerves and covering tissues. The two major types of brain tumor are primary and secondary. Primary brain tumors start in the brain. Secondary brain tumors start in another part of the body, then spread to the brain. A glioma is a primary brain tumor, accounting for 45% of cancers that begin in brain cells.
The three main types of glioma include: astrocytoma, ependymoma, and oligodendroglioma. Each of these types can be assigned a grade, either low grade or high grade, with high grade being more malignant and aggressive.
Astrocytomas are named for the cells where they originate, the astrocytes. These tumors can either show clear borders between normal brain tissue and the tumor (called focal) or no clear border (called diffuse). Focal astrocytomas, more common in children, are not often found in adults.
Ependymomas begin in cells called ependymal cells that are found lining certain areas of the brain and spinal cord. These cells help repair damaged nerve tissue. They usually occur in children and young adults.
Oligodendrogliomas form in oligodendrocyte cells, which produce a fatty substance called myelin that protects the nerve. More common in adults, these tumors may move to other parts of the brain or spinal cord.