Causes of Neurofibroma

Neurofibromas are tumors composed of soft, fleshy growths of nerve tissue. It's possible for them to affect any nerve in the body, but they're most commonly associated with peripheral nerves--those outside the brain and spinal cord. In particular, they usually involve the connective nerve tissue of the skin. They feel like small, rubbery lumps under the skin. They usually make their first appearance during childhood--particularly during adolescence. Neurofibromas are typically benign; however, in 3 percent to 5 percent of cases, they become malignant.

Relationship to Neurofibromatosis

• Neurofibromas result from a condition known as Type 1 neurofibromatosis (NF1), which is also sometimes known as Von Recklinghausen's disease. NF1 affects about one in every 3,000 to 4,000 people. Neurofibromas are just one of the characteristics of neurofibromatosis. Others include bone defects, tan patches or freckles on the skin (especially in the armpit or groin) and visual disturbances. NF1 accounts for about 90 percent of all cases of neurofibromatosis. A much rarer form of neurofibromatosis, known as Type 2 (NF2), results in neuromas in the brain, causing hearing loss, headaches, dizziness and weakness in the face. Skin neurofibromas are not typically associated with NF2.

Role of Heredity

• About half of those who are afflicted with neurofibromatosis inherit it. NF1 is an autosomal dominant genetic disorder, which means that in cases in which the gene is inherited, only one gene is needed from one parent in order to pass the disease on to offspring. Thus, a parent who carries the gene has a 50 percent chance of passing it on each time a child is conceived.

Genetic Testing and Counseling

• Because neurofibromatosis is a hereditary disorder, genetic counseling is available and recommended for those who think their offspring might be at risk. The exact chromosome with which the NF1 gene is associated---chromosome 17-- has been determined, which facilitates testing for the disease. A blood test may help to determine who is a carrier.

Non-inherited Neurofibromatosis

• Given that half of those who develop neurofibromas inherit the condition, it stands to reason that the other half of the population affected by the disease has no family history of the disease. In these cases, spontaneous genetic mutation--a mutation in the genetic material of the sperm or egg--is the cause. Abnormal differentiation and migration of neural cells can occur during the development of the embryo, which takes place from conception until about the eighth week of a pregnancy. Parents who have a child with neurofibromatosis but don't have the condition themselves have a very small chance of having another child with the disease.

Treatment

• There is no known cure for neurofibromatosis, but neurofibromas can be surgically removed or shrunk through radiation therapy. This is most often considered if the neurofibromas cause pain or disfigurement. These tumors are often difficult to separate from the nerve structure itself, so when surgery is the course of action, it may be necessary to remove the nerve along with the neurofibroma.