A ganglioglioma is a rare type of brain tumor, accounting for approximately 1% of all brain tumors. Gangliogliomas occur when a single cell in the brain starts to divide into more cells, forming a tumor. This can occur when the cell randomly acquires changes (mutations) in genes that regulate how a cell divides. Most gangliogliomas grow slowly and are considered benign. However, up to 10% of gangliogliomas may grow more rapidly and become malignant, meaning the tumor affects the surrounding brain tissue. The main treatment for ganglioglioma is removal of the entire tumor during surgery. If the entire tumor is not removed, it has the potential to recur and may require additional surgery or treatments, such as radiation therapy or chemotherapy. Unfortunately, because gangliogliomas are quite rare, there is limited information to show that radiation therapy or chemotherapy are effective treatments for this condition. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.