Neuroblastoma is a very rare cancer which develops from immature nerve cells, called neuroblasts . Instead of becoming working cells, their uncontrollable growth creates a tumor . Neuroblastoma often begins in neuroblasts of the tissue of the adrenal gland, which is an endocrine gland found on top of the kidney . Hormones produced by the adrenal gland assist in controlling blood pressure, metabolism, and the body's reaction to stress . Neuroblastoma can also begin in other body parts which have clusters of nerve cells, and can metastasize to other parts of the body . Neuroblastomas primarily affect babies and adolescents, usually under the age of five and rarely older than ten, because they have the most nerve cells which are still developing . Symptoms of a neuroblastoma include a lump that can be seen or felt, swelling, and more based on the location of the tumor . Neuroblastoma is diagnosed through physical exams, blood and urine tests, imaging, and tissue and bone marrow biopsies . There are four stages of neuroblastoma: the lowest risk stage, L1, where tumors are in one part of the body, don't affect vital structures, and haven't spread; L2, where the tumor is still in one body compartment, but vital structures are involved and cancer cells have spread to regional structures like lymph nodes; M, when the cancer has become metastatic; and the "special" MS category, which is when the neuroblastoma has extended to the bone marrow, liver, or skin in children younger than eighteen months, and this stage is considered low risk .