Medulloblastoma is a type of brain tumor. A brain tumor begins when healthy cells in the brain change and grow out of control, forming a mass. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can grow and spread to other parts of the body. A benign tumor means the tumor can grow but will not spread.
The brain and spinal column make up the central nervous system (CNS), where all vital functions are controlled, including thought, speech, and body strength. Medulloblastoma begins in different cells in the cerebellum, which is the back of the brain. The cerebellum controls body movement and coordination.