Neuroblastoma: Nursing

Neuroblastoma is a malignant tumor composed of neural crest cells, which are embryonic nerve cells. In fact, neuroblastoma is the most common extracranial cancer in infants, and it’s only rarely seen in children over five years old.

But let’s review some basic physiology first. During embryonic development, special cells called neural crest cells start migrating along the spine. In the thoracic region of the spine, neural crest cells differentiate into the neurons of the sympathetic chain, lying on either side of the entire spinal cord. In the lumbar region, neural crest cells differentiate into the cells of the adrenal medulla, the inner part of the adrenal gland that sits atop the kidneys. Together, the sympathetic chain and adrenal medulla form the sympathetic nervous system, connecting the brain and central nervous system to various organs including the heart and blood vessels.

When an individual is under stress, the sympathetic nervous system releases norepinephrine, and the cells of the adrenal medulla release norepinephrine and epinephrine. These hormones bind to receptors in various tissues like the blood vessels, the heart, and the lungs. After the stress is over, and the hormones are no longer needed, they are broken down into metabolites to be eliminated from the body.

Although the exact cause of neuroblastoma remains unknown, several non-modifiable risk factors have been recognized. These include family history of neuroblastoma and genetic mutations in the MYCN oncogene, the ALK fusion oncogenes, and mutations in tumor suppressor genes, like the PHOX2B gene.

Alright, now, regardless of the risk factor, in neuroblastoma, some neural crest cells in the sympathetic chain or adrenal medulla don’t differentiate properly during fetal development. And these cells ultimately go on to form a tumor, most commonly in the adrenal medulla, or other areas of the sympathetic chain. When any type of neuroblastoma forms, cells in the surrounding tissue release chemokines that stimulate nearby immune cells. As the tumor gets larger it can go on to compress nearby structures, including nerves and blood vessels. Eventually, neuroblastoma cells may get into the circulation and metastasize to distant organs, such as the liver, bones, and bone marrow.

Now, signs and symptoms of neuroblastoma result from the chemokine release, and include fever, weight loss, sweating, and fatigue. Other symptoms of neuroblastoma depend on where the tumor is located, and are usually a result of the tumor pressing up against surrounding organs.

Typically neuroblastomas form in the adrenal glands as solid, irregular abdominal masses that cause abdominal swelling and as opposed to nephroblastomas, which is a tumor of the kidney, cross the midline. Now, if the tumor is in the thoracic region of the sympathetic chain, it can grow into the lungs, causing breathing difficulties.

A thoracic tumor that extends to the neck can press up against nerves originating there and heading towards the face, it can cause Horner syndrome. Horner syndrome involves miosis or constriction of the pupils, ptosis or the drooping of the eyelid, and anhidrosis which is the inability to sweat in the face.

Tumors on the sympathetic chain might also grow into the spine, causing neurologic symptoms, like muscle weakness or bowel and bladder problems. About half of all neuroblastomas spread to the bones, usually at the base of the skull, causing bone pain and small fractures. With these fractures, fluid and blood leak into the tissues around the eyes. When that happens it can cause periorbital ecchymosis, also called raccoon eyes, because of the dark rings of blood that can be seen in the soft tissue around the eyes. Neuroblastoma that invades the bone marrow can also affect the marrow’s ability to make healthy red blood cells, platelets, and white blood cells, leading to fatigue, easy bruising, and frequent infections.

Alright, now diagnosis of neuroblastoma starts with the client's history and physical assessment, followed by additional diagnostic tests, which typically show elevated blood and urine levels of catecholamines and their metabolites. Additionally, a complete blood count can also help determine whether neuroblastoma has spread to the bone marrow.