Medulloblastoma Updated 2/4/03 MRI of a medulloblastoma Taken from the web.    Unlike healthy cells, which perform useful tasks in our bodies, cancer cells grow in an abnormal, uncontrolled manner, and instead of contributing to the the normal functioning of our bodies, they make us sick.  There are many types of cancer which affect different parts of the body.  Mo had a solid tumor which was removed from the part of the brain called the cerebellum.  Thankfully it was discovered before it had spread to other parts of his body. Brain cancer in children is a rare disease. There are about 2200 pedeatric brain tumors diagnosed in the U.S. each year.  Medulloblastoma is the most common form of brain cancer in children - accounting for 20-25% of the total.  No one knows for sure the cause of this type of tumor. Genetics definitely play a role for some patients, and it is believed to arise from primitive neuroectodermal tissue, which is the early fetal tissue that eventually develops into the brain.  It tends to grow quickly, and often spreads to other parts of the central nervous system.  Rarely, it can spread to other parts of the body.