Definition

Neurofibromatosis (NF) is a genetic disorder of the nervous system. It causes tumors to grow on the nerves in any part of the body. NF can also produce other abnormalities, such as:

  • Changes in skin color
  • Deformity of bones

The Nervous System

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There are two types:

  • NF1—caused by mutations (or changes) of the neurofibromin gene (more common)
  • NF2—caused by mutations of the merlin gene

Causes

NF is caused by a change in a gene. In many cases the abnormal gene is inherited. However, frequently the gene changes occur by chance in a person with no family history of NF. A person with the inherited form of NF has a 50% chance of passing on the abnormal gene each time he or she has a child. Also, all first-degree relatives (parents, children, and siblings) of an affected individual should be considered at risk and evaluated for signs of NF.

Risk Factors

The main risk factor for NF is having a family member with the disease.

Symptoms

NF1 and NF2 have different symptoms. With either type, the symptoms can range from mild to severe. In most cases, the symptoms are mild and may be overlooked.

Symptoms of NF1

  • Light brown spots (called café-au-lait spots) on the skin
  • Neurofibromas (tumors that grow on a nerve or nerve tissue)— rarely occur before puberty
  • Soft tumors, which may have a darker color
  • Freckles in the armpits or groin
  • Growths on the iris
  • Tumor on the optic nerve that may affect vision
  • Severe scoliosis (curved spine)
  • Deformed or enlarged bones other than the spine
  • Mild impairment of intellectual function, attention deficit disorder
  • Seizures

Most of these symptoms begin between birth and age 10.

Symptoms of NF2

  • Several tumors on the nerves of the brain and spine—Most common are tumors that affect the nerves to the ears. Hearing loss may begin as early as the teen years.
  • Other symptoms may include:
    • Tinnitus (ringing in the ear)
    • Poor balance
    • Headaches
    • Pain or numbness in the face

Diagnosis

The doctor will ask about your:

  • Symptoms
  • Medical history
  • Family medical history

The doctor will also do a physical exam. The diagnosis is generally made based on physical findings. Examples include:

  • Cafè-au-lait spot (main sign of NF)—Adults with six or more spots greater than 1.5 cm in diameter are likely to have NF.
  • Freckling in the armpits, groin, or underneath the breast in women
  • Multiple soft tumors apparent on the skin or deeper in the body viewed by radiologic testing (scans)
  • Soft nodules under the skin
  • Large infiltrating tumors under the skin, which can cause disfigurement and can progress to become malignant peripheral nerve sheath tumors
  • Pigmented, raised spots on the colored part of the eye

Tests for NF1 may include:

  • Exam by a doctor familiar with NF1 (eg, neurologist, geneticist, dermatologist)
  • Eye exam by an ophthalmologist familiar with NF1
  • Removal of neurofibromas for testing
  • Other specific tests associated with complications
  • MRI scan —a test that uses magnetic waves to make pictures of structures inside the brain
  • Genetic testing—available for families with a history of NF1 and NF2. Prenatal diagnosis may be possible with amniocentesis or chorionic villus sampling.

Treatment

Treatments for both types of NF are aimed at controlling symptoms. NF tumors are not always treated because they:

  • Grow slowly
  • Are rarely cancerous
  • May not cause problems

If you have NF, you will need regular exams to check for:

  • Tumors
  • Brown spots on the skin
  • Bones, including scoliosis
  • Hearing
  • Vision

Treatment of NF1

Surgery can help correct some bone abnormalities. Bone surgery may be combined with back braces to treat scoliosis. Surgery can also be used to remove painful or disfiguring tumors. However, tumors may grow back and in larger numbers. In rare cases when tumors become cancerous, treatment may include:

Treatment of NF2

Surgery can remove tumors, but it may damage the nerves. If the nerves to the ears are damaged, hearing loss can occur. Other treatment options include:

  • Partial removal of tumors
  • Radiation

MRI scans of the brain can locate tumors when they are small. This allows treatment to be started early.

Prevention

There are no guidelines for preventing NF.