If a child has symptoms of neuroblastoma, blood and urine tests, tissue samples, and imaging studies will be needed. These tests are important because many of the symptoms and signs of neuroblastoma also can be caused by other cancers or by non-cancerous diseases.
Normal nerve cells release chemicals called neurotransmitters that control nerve activity. Catecholamines are the main group of neurotransmitters produced by cells of the sympathetic nervous system. The body breaks down the catecholamine molecules into metabolites, or smaller pieces, and they are passed out of the body in the urine.
In about 90 percent of cases, neuroblastoma causes elevated levels of catecholamines or neurotransmitters, which are detected by blood or urine tests. Some of the symptoms associated with neuroblastoma — such as high blood pressure, rapid heartbeat or diarrhea — are caused by increased catecholamines.
Your child's doctor may order other blood tests to check liver and kidney function and salt balance. A urinalysis will be conducted to further check kidney function.
Imaging tests include diagnostic X-rays and other procedures that produce images or pictures of the body's interior. Two or more of these tests are generally used to identify tumors in areas where neuroblastomas tend to spread. These tests may include:
If blood or urine levels of catecholamines or their metabolites are elevated, then finding cancer cells in a bone marrow biopsy is sufficient evidence for a diagnosis of neuroblastoma. The disease spreads to bone marrow in about a quarter of patients.
Bone marrow can be sampled in two ways, and both are generally done at the same time. A bone marrow biopsy uses a large needle to remove a cylindrical piece of the bone about 1/2 inch long and 1/16 inch across. A bone marrow aspiration uses a thinner needle and a syringe to extract cells from the marrow, the soft tissue inside bone cavities.
Alternatively, tissue samples can be taken from the primary tumor. If examination under the microscope shows certain features typical of neuroblastoma, a definite diagnosis can be made, even if catecholamine levels are not elevated. Some cases of neuroblastoma are easily recognized under a microscope when examined by doctors experienced in testing children's tumor samples.
Other cases of neuroblastoma have features easily confused with other types of children's cancers. In these cases, special tests of the tissue samples must be done. For example, immunohistochemistry uses special laboratory antibodies that specifically recognize chemicals found in neuroblastoma cells and other antibodies that recognize chemicals of other cancer cells. Electron microscopy uses a special microscope hundreds of times more powerful than usual laboratory microscopes, and can recognize tiny packages of catecholamines inside neuroblastoma cells and other abnormalities.
When neuroblastoma is diagnosed, your child's doctor may use the following categories or terms to describe the cancer:
Reviewed by health care specialists at UCSF Benioff Children's Hospital.