Medulloblastomas are tumors located in the cerebellum, the part of the brain that controls balance and other complex motor functions. They grow most often in the central part of the cerebellum, and less frequently in the outer parts of the cerebellum.
Medulloblastoma is the most common malignant (cancerous) central nervous system tumor in children. It accounts for 15 to 20 percent of all pediatric brain tumors. Medulloblastomas occur most commonly in children between ages of 3 and 8 but can be seen in children and adults of any age.