is a tumor that develops from a nerve in a child, usually before the age of 5. It occurs in the abdomen near the adrenal glands, but it can also occur in other parts of the body. It is considered an aggressive tumor because it often spreads to other parts of the body (metastasizes). The symptoms of a neuroblastoma may include a lump in the abdomen, pain, diarrhea, or generally feeling unwell. It affects one out of 100,000 children. The exact cause of this tumor is not yet known. Neuroblastoma may be diagnosed by physical examination; specific blood tests; imaging tests such as x-rays, magnetic resonance imaging (MRI), or computed tomography (CT) scans; and a biopsy. Treatment depends on the size and location of the tumor within the body, as well as the childÕs age. Surgery is often the first step of treatment, and may be followed by chemotherapy, radiation therapy, or a stem cell transplant in more severe cases. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.