Childhood medulloblastoma is a disease in which benign (noncancer) or malignant (cancer) cells form in the tissues of the brain.

Childhood medulloblastoma (tumor) usually forms in the cerebellum, which is at the lower back of the brain. The cerebellum is the part of the brain that controls movement, balance, and posture. Childhood medulloblastoma may also be called primitive neuroectodermal tumor (PNET).

About 1 out of 5 childhood brain tumors are medulloblastomas. Although cancer is rare in children, brain tumors are the most common type of childhood cancer other than leukemia and lymphoma.

This summary refers to the treatment of primary brain tumors (tumors that begin in the brain). Treatment for metastatic brain tumors, which are tumors formed by cancer cells that begin in other parts of the body and spread to the brain, is not discussed in this summary. See the PDQ treatment summary on Childhood Brain Tumors for information about the different types of childhood brain and spinal cord tumors.

Brain tumors can occur in both children and adults; however, treatment for children may be different than treatment for adults. (See the PDQ treatment summary on Adult Brain Tumors for more information.)

The cause of most childhood brain tumors is unknown.

The signs of childhood medulloblastoma vary and often depend on the child’s age and where the tumor is located.

Symptoms caused by medulloblastoma may also be caused by other conditions. A doctor should be consulted if any of the following problems occur:

• Loss of balance, trouble walking, worsening handwriting, or slow speech.
• Morning headache or headache that goes away after vomiting.
• Nausea and vomiting.
• Unusual sleepiness or change in energy level.
• Change in personality or behavior.
• Unexplained weight loss or weight gain.

Tests that examine the brain and spinal cord are used to detect (find) childhood medulloblastoma.

The following tests and procedures may be used:

• CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
• MRI (magnetic resonance imaging) with gadolinium: A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the brain and spinal cord. A substance called gadolinium is injected into a vein. The gadolinium collects around the cancer cells so they show up brighter in the picture. This procedure is also called nuclear magnetic resonance imaging (NMRI).

Childhood medulloblastoma is diagnosed and removed in surgery.

If a brain tumor is suspected, a biopsy is done by removing part of the skull and using a needle to remove a sample of the tumor tissue. A pathologist views the tissue under a microscope to look for cancer cells. If cancer cells are found, the doctor will remove as much tumor as possible during the same surgery.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis (chance of recovery) and treatment options depend on:

• The age of the child when the tumor is found.
• The location of the tumor.
• The amount of tumor remaining after surgery.
• Whether the cancer has spread to other parts of the central nervous system (brain and spinal cord), or to other parts of the body, such as the bones.