Neurofibromatosis (NF Disease): Each Type Explained
The three types have similarities and differences
Medically reviewed by Brigid Dwyer, MDMedically reviewed by Brigid Dwyer, MD
Neurofibromatosis (NF) is a genetic neurological condition that is usually inherited. There are three types of neurofibromatosis: NF-1, NF-2, and schwannomatosis (sometimes called NF-3).
The main feature all three types have in common is that people with NF can develop tumors in the brain, spinal cord, and nerves. Most NF tumors are slow-growing and noninvasive, but the condition can also predispose to dangerous invasive tumors.
Symptoms such as pain, hearing loss, or dizziness can occur because the tumors can compress and damage important areas of the nervous system. This article describes neurofibromatosis types 1, 2, and 3.
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Neurofibromatosis Types 1-3
Of the three types of neurofibromatosis, the most common is NF-1, with a prevalence of about 1 in 3,000 to 4,000 people. It’s estimated that NF-2 has a prevalence of about 1 in 60,000 people. Schwannomatosis is estimated to affect approximately 1 in 40,000 people.
Symptom Onset
The symptoms of neurofibromatosis can become evident at any time between infancy and adulthood. Each type of NF is known for a typical age of symptom onset—but your symptoms can emerge sooner or later than the average.
Typical symptom onset for NF types are:
NF-1: Symptoms usually become noticeable during infancy or early childhood. Older children, adolescents, and adults can continue to develop new tumors and skin changes over time.
NF-2: Symptoms usually begin during late childhood, adolescence, or early adulthood.
Schwannomatosis: Symptoms typically start during adulthood and can begin to emerge after age 30.
Appearance and Sensations
Each type of neurofibromatosis has specific patterns of symptoms. NF-1 has many different signs, while the effects of NF-2 primarily involve hearing loss and impaired physical balance.
Signs and symptoms of NF include:
NF-1: The earliest and most noticeable signs are dark spots on the skin, called café au lait spots. Other skin changes include bumps under the skin and freckles on the groin and underarms. Most people with NF-1 have plexiform neurofibromas, tumors that grow on a bundle of nerves. You can also develop bumps and tumors in your eyes, which can affect vision. Bone problems are common, including bowed legs, scoliosis, or thinned bones.
NF-2: Acoustic neuromas, tumors of the nerves that affect hearing and balance, are the characteristic features of NF-2. People with NF-2 have bilateral acoustic neuromas, affecting both the right and left sides.
Schwannomatosis: This condition causes slow-growing tumors of the nerves, brain, and spinal cord. These tumors are called schwannomas because they arise from a type of nerve cell called a Schwann cell. Generally, schwannomas are benign tumors, meaning they are not expected to spread to other areas of the body.
How Do Children Acquire Neurofibromatosis?
All types of neurofibromatosis result from genetic changes, usually called mutations, that cause tumor growth and other effects of NF. A child can inherit the genetic mutations from a parent.
While NF is usually inherited, it can also develop without inheriting the genetic mutations—the mutations can occur spontaneously and without a known cause.
If an individual develops a new NF mutation without inheriting it from their parents, they could pass on the disease to their children.
Inheritance patterns of NF genes are:
NF-1: This condition is caused by a mutation in the NF-1 gene, which can be inherited in an autosomal dominant pattern (a person who inherits the gene from either parent will develop the disease, and the gene is not on a sex chromosome) or can arise spontaneously without being inherited.
NF-2: This condition is caused by a mutation in the NF-2 gene, which can be inherited in an autosomal dominant pattern or can arise spontaneously without being inherited.
Schwannomatosis: This type of NF can be caused by a mutation of the SMARCB or LZTR1 genes, but sometimes, no genetic cause is identified.
How Do Adults Acquire Neurofibromatosis?
The common forms of NF are due to inherited or spontaneous mutations present before birth. It is not a disease that adults acquire. However, the symptoms can sometimes not begin until adulthood adulthood.
Risks and Complications
Each type of neurofibromatosis causes growths or tumors in the nervous system. The tumors can cause symptoms and can also be dangerous.
Benign (noncancerous) tumors of NF-1 and schwannomatosis can cause pain, bumps, and swelling. Sometimes, the tumors may also cause symptoms such as weakness, sensory loss, or seizures due to compression of structures in the nervous system.
Acoustic neuromas of NF-2 can cause hearing loss and impaired balance, substantially affecting a person’s abilities and quality of life.
Tumors of any type of NF can grow and compress vital structures within the nervous system, potentially becoming life-threatening. This can occur even with benign tumors. Additionally, while it’s not common, sometimes NF can predispose a person to malignant (cancerous) tumors, which could spread to other regions of the body and may be life-threatening.
Path to Neurofibromatosis Diagnosis
Neurofibromatosis is definitively diagnosed based on genetic testing. Often, people who have a family history of NF will have a genetic test even before symptoms develop.
Signs of NF can be detected with a physical examination, which can identify café au lait spots, bumps on the skin, freckles, hearing loss, and balance problems.
Imaging tests can sometimes identify plexiform neurofibromas or other tumors. In some cases, a biopsy (a sample of tissue that’s obtained surgically) can be examined with a microscope to identify tumor cells.
Delayed Diagnosis
If you or your child has some symptoms of NF and does not have a family history of the condition, it may take longer for your healthcare provider to consider this diagnosis and to order genetic testing.
What a Neurofibromatosis Diagnosis Means in Terms of Cancer/Outlook
People who have neurofibromatosis have a higher risk of cancer than people in the general population. Additionally, having cancer with NF reduces life expectancy and survival compared to having NF without cancer.
If you or your child has NF, it’s important that you discuss screening with your healthcare provider. You may need a schedule for cancer screening, which could include blood tests, imaging, and physical examinations.
Cancer Risk and Surveillance
If you develop any symptoms that could indicate cancer, such as increasing headaches, new bumps, pain, or unexplained weight loss, it’s crucial to call your healthcare provider. Discuss your symptoms and whether you need any screening or diagnostic tests.
Treatment to Manage Symptoms
Treatments for neurofibromatosis are centered around managing symptoms and treating tumors. Surgery is often considered for tumor removal in NF. You and your healthcare provider can discuss your surgery options and the risks and benefits.
Neurofibromatosis Type 1
Treatment for NF can include pain management with over-the-counter (OTC) or prescription pain medication, injections for pain treatment, and nerve blocks. Additionally, you may need surgical removal of tumors that are causing consistent and problematic symptoms.
Koselugo (selumetinib) is an oral capsule approved for treating plexiform neurofibromas that cannot be surgically treated in children age 2 and older.
Neurofibromatosis Type 2
Hearing loss is the most prominent symptom of NF-2. Acoustic neuroma can sometimes be treated with surgery, radiation, or chemotherapy.
Hearing loss can interfere with speech and language, particularly if it starts at a young age when children are still developing speech skills. Speech therapy can be beneficial in learning how to communicate with hearing impairment.
If you have balance problems due to NF-2 acoustic neuroma, you may benefit from participating in physical therapy to help improve your balance.
Neurofibromatosis Type 3
Schwannomas can sometimes be removed surgically. Instead of surgical treatment, you may need to have your tumors monitored periodically with physical examination or imaging, particularly if they are not causing symptoms.
Related: Malignant vs. Benign Tumors: What Are the Differences?
Neurofibromatosis Support and Awareness
If you or your child has a risk of NF because of a family history, it’s important that you get a diagnosis at an early stage. Diagnosis will include a clinical evaluation and genetic testing. Knowing whether you or your child has a gene that causes NF can help in planning early treatment and may also help make decisions about family planning.
After a neurofibromatosis diagnosis, it’s important to seek care from an NF specialist or at an NF specialty clinic to get ongoing medical care, including surveillance for tumors.
Support Groups
It can be beneficial for you and your family to connect with an NF community so that you can be informed about the latest treatments, clinical trials, and strategies for coping with this condition.
Knowing what to expect from others who have been through what you are going through can be helpful and a great source of support.
If you have the interest and energy, you might also consider offering emotional support, advice, and encouragement to others living with NF. You might decide to put your effort into NF advocacy, raising awareness for improved care and research for people with this condition.
Summary
There are three different types of neurofibromatosis: NF-1, NF-2, and schwannomatosis. They are all characterized by nonmalignant tumors in the nervous system.
Each type of NF is caused by distinct genetic changes that can either be inherited or occur spontaneously. Many people with NF have one or more family members with the condition. Symptoms can involve pain, sensory changes, weakness, balance problems, and hearing loss.
Treatment of NF can include symptomatic treatment for pain, surgical tumor removal, or selumetinib for treatment of NF-1 plexiform neurofibromas that cannot be surgically removed. You can live a long and healthy life with NF. However, with it there is an increased risk of cancer, so ongoing surveillance and screenings are crucial.
If you or your child has a form of NF, it’s important that you maintain consistent medical care so that you can have surveillance of tumors and tumor growth and so that you can receive timely treatment for your symptoms and for any tumors that could be dangerous or life-threatening.
Read the original article on Verywell Health.
