Neurofibromatosis Type 1 (NF1): What It Is & Symptoms

The neurofibromatoses are a part of a group of conditions known as neurocutaneous disorders that affect the skin and the nervous system. (“Neuro” refers to nerves and “cutaneous” refers to skin.)

These types of disorders are caused by abnormal increases in cell growth. This results in the formation of tumors all over the body. In particular, these tumors can grow on nerves, causing problems with the skin, bones, eyes and elsewhere.

neurofibromatoses 

There are two main subtypes of neurofibromatoses:

• Neurofibromatosis type 1 (NF1), which accounts for about 90% of all cases of neurofibromatosis. NF1 happens in about 1 in 3,000 births. This type has also been called Von Recklinghausen disease.
• Neurofibromatosis type 2 (NF2), which is much less common, especially in children. NF2 happens in about 1 in 25,000 to 1 in 40,000 live births, according to various estimates.

What causes neurofibromatosis type 1 (NF1)?

Neurofibromatosis is generally an inherited disorder of the autosomal dominant kind. This means that only one copy of a mutant gene is needed to produce the condition, and patients have a 50:50 chance of their children getting the disorder.

Neurofibromatosis also can be caused by spontaneous mutation (change) in up to 50% of cases. Once the change in genes happens, it can be passed on to the next generation.

What are some signs and symptoms of neurofibromatosis type 1 (NF1)?

Common signs and symptoms of NF1 include:

• Café-au-lait spots (also called café-au-lait macules): These are flat patches of light brown or coffee-colored skin. Initially, you might see them on your infant and think the spots are freckles. The spots may get larger and more numerous during your child's first few years of life (up to about 7 years old). A child with NF1 is likely to have at least six or more of these spots that are larger than freckles. The spots themselves are not painful. Even people who don’t have neurofibromatosis can have one or two café-au-lait spots that are benign (non-cancerous).
• Lisch nodules: These are small non-cancerous growths located on the iris (the colored part) of the eyes. Lisch nodules don’t cause problems with vision, but tumors might later develop in the eye. These tumors are called optic gliomas. They may or may not affect vision.
• Neurofibromas: These are non-cancerous tumors that are located mostly under the skin. Neurofibromas may also grow on nerves. There is a certain type of neurofibroma called a plexiform neurofibroma that comes with a 5% to 10% risk of developing a malignant peripheral nerve sheath tumor (MPNST).
• High blood pressure (hypertension).
• Short stature (height).
• Macrocephaly (an unusually big head).
• Bone abnormalities, such as scoliosis (a curved spine) or bowing (curving) of leg bones.
• Learning disabilities.
• Attention deficit hyperactivity disorder (ADHD).
• Seizures.
• Speech problems.
• Many freckles under the armpit or in the groin region — called axillary or inguinal freckling.

There may be other complications associated with NF1, including vascular (blood vessel) conditions that affect the central and peripheral nervous systems. One condition in particular is one that involves arterial narrowing called Moyamoya disease.

How is neurofibromatosis type 1 (NF1) diagnosed?

NF1 is generally diagnosed by a physical examination. The diagnosis is made by finding a certain number of the signs and symptoms listed previously, such as the freckling under the arm and the bone abnormalities. Someone with NF1 will have two or more of these symptoms and no other disease that can account for them. There is a specialized blood test that can determine if someone has NF1.

How is neurofibromatosis type 1 (NF1) managed?

At this time, NF1 can’t be cured. However, symptoms can be followed and managed. Because the symptoms differ between people, the management and treatments also may differ.

• If you have NF1, you should have at least one regular medical follow-up examination every year, along with an ophthalmologic (eye) examination every year. In addition, you should get your blood pressure taken at least every year to see if the renal (kidney) arteries are narrowing.
• Surgery can remove disfigurements caused by neurofibromas.
• The cholesterol drug lovastatin is being used to treat learning disabilities and ADHD.
• If you have NF1, you might find it useful to get psychological and social support, and possibly genetic counseling.

How are neurofibromatosis type 1 (NF1) tumors treated?

Neurofibromatosis type 1 produces tumors of the skin, internal organs, and nerves because normal genes that control cell growth are affected. These tumors are treated as follows:

• Dermal neurofibromas: Surgery is usually recommended if these skin tumors are painful or irritating.
• Plexiform neurofibromas: These tumors are deeper than dermal neurofibromas and affect nerves. Your healthcare provider may choose to monitor these tumors are and not treated them, but chemotherapy and surgery are options.
• Malignant peripheral nerve sheath tumors (MPNST): These tumors develop from plexiform lesions. The diagnosis is made by surgery. Treatment involves surgery, radiation therapy and chemotherapy.
• Gastrointestinal stromal tumors (GIST): These tumors develop in the small intestine. They are treated with surgery. Several chemotherapy trials are under way.
• Optic nerve glioma and astrocytoma: These tumors develop in the eye (optic nerve glioma) and brain (astrocytoma). The grade of the tumor usually defines how fast it grows and how difficult it is to treat. Grade 4 astrocytomas are the most aggressive brain tumors and the most difficult to treat. If you’re diagnosed with a brain tumor, you should seek a specialist in neuro-oncology.