A glioma is a type of tumor that starts in the brain or spine. It is called a glioma because it arises from glial cells. The most common site of gliomas is the brain. Gliomas make up about 30% of all brain and central nervous system tumors and 80% of all malignant brain tumors.
Gliomas are classified by cell type, by grade, and by location.
Gliomas are named according to the specific type of cell with which they share histological features, but not necessarily from which they originate. The main types of gliomas are:
Gliomas are further categorized according to their grade, which is determined by pathologic evaluation of the tumor.