What Causes Neuroblastoma?

What is Neuroblastoma?

Neuroblastoma is a type of tumor that develops from the nerve cells present in several body parts. It is more commonly found in children below the age of five. It is rarely found in older children and adults. It is the most common cancer observed in babies. It generally starts in early childhood. However, it is not diagnosed until its symptoms appear. This type of tumor starts in the adrenal glands that are located in the upper abdomen above the kidneys. However, it can also develop in other areas of abdomen as well as neck, chest and pelvis, which consist of groups of nerve cells.

Causes of Neuroblastoma

The exact causes of neuroblastoma are not clear. Generally, a cancer starts with genetic mutation leading to a continuous, uncontrolled growth of normal, healthy cells. An accumulation of these abnormal cells causes a formation of mass (tumor). Cancer cells invade nearby tissues and they can break off from the initial tumor to spread into other body parts (metastasize).

Neuroblastoma starts in the immature nerve cells (neuroblasts) of a fetus. When the fetus matures, neuroblasts are developed into nerve cells and fibers as well as the cells that compose the adrenal glands. Most of the neuroblasts mature at the time of birth. However, there may be a small number of immature neuroblasts, which either mature or disappear. Some immature neuroblasts fail to mature to develop into normal adrenal cells or nerves. They form a tumor, known as neuroblastoma and keep growing and proliferating. Most neuroblastoma cells possess the genetic abnormalities involving chromosome #1. This chromosome abnormality causes amplification of oncogene, namely, n-myc. It leads to uncontrolled growth of the cell. About 20% cases of neuroblastoma result from an inherited mutation, followed by the second mutation after birth. Other cases can result from two acquired mutations after birth. Children born with neurofibromatosis, fetal hydantoin syndrome and Beckwith-Wiedemann Syndrome are at higher risk of developing neuroblastoma. A family history of cancer increases the risk of neuroblastoma.

Symptoms of Neuroblastoma

Signs and symptoms of neuroblastoma depend upon which body part is affected. Most neuroblastomas occur in the abdomen and about 15% in the chest. Neuroblastoma in pelvis or neck is less common. Some of the symptoms of abdominal neuroblastoma are abdominal pain, a tender mass under the skin, a feeling of fullness in the abdomen, changes in bowel habits such as constipation, changes in urinary habits such as increased urination frequency and swelling in the legs. Neuroblastoma in chest causes the symptoms such as swelling in the face, wheezing, changes in the eyes such as unequal pupil size and dropping eyelids. Other symptoms of neuroblastoma are tissue lumps under the skin, back pain, protruding eyeballs, scoliosis (curvature of spine), fever, bone pain and unexplained weight loss.

Complications of Neuroblastoma

Neuroblastoma can cause a number of complications. It can spread to other body parts such as bone marrow, lymph nodes, liver, eyes, skin and tissue surrounding the spinal cord. There may be spinal cord compression due to tumor growth. Compression of spinal cord can result in extreme pain and paralysis. Neuroblastomas secrete certain chemicals, which cause an irritation of other normal tissues, leading to paraneoplastic syndrome.