Neuroblastoma: Year of the Zebra 2024

Neuroblastoma is a type of cancer that arises from neural crest cells, which are cells involved in the development of the nervous system. 

Normally, neural crest cells migrate throughout the body to form a range of structures including the sympathetic chain ganglia, nerve cells that lie on either side of the spinal cord, and the adrenal medulla, the innermost part of the adrenal gland.

With neuroblastomas, some of these neural crest cells do not mature properly during fetal development, and instead continue to divide in their immature state until they form a tumor. 

Most commonly, neuroblastomas form in the adrenal medulla, but they can also develop in other areas of the sympathetic chain, including the neck, chest, abdomen, or near the spine. 

These tumors typically affect infants and are rarely seen in children over five years old.

While no one knows the exact cause, this abnormal cell development has been associated with mutations in growth-regulating genes, such as the MYC, ALK, and PHOX2B genes.

Clinical manifestations of a neuroblastoma depend on the location and size of the tumor.

For example, a tumor in the adrenal glands can present with a large, painful abdominal mass that causes abdominal swelling; whereas a tumor in the chest can grow into the lungs, causing breathing difficulties and abnormal breath sounds.

Tumors near the spine may compress one or more spinal nerves causing neurologic symptoms, like muscle weakness and bowel or bladder dysfunction.

Similarly, tumors in the neck can press on the nerves originating from that region, resulting in a collection of symptoms known as Horner syndrome.

Horner syndrome may result in a drooping eyelid, small pupil in one eye, and decreased sweating on one side of the face.

About half of all neuroblastomas spread to the bones, causing bone pain and an increased risk of fractures.