Schwannomatosis

What is schwannomatosis?

Schwannomatosis is a broad name for several genetic conditions that cause tumors to form on nerves in your body. These tumors are known as schwannomas. They develop from insulating nerve cells called Schwann cells in your peripheral nervous system (nerve roots, nerves and nerve-muscle junctions). Schwannomatosis usually leads to chronic pain that typically starts in early adulthood.

Schwannomatosis is a type of neurofibromatosis. This is a group of conditions that cause tumors to grow in your nervous system.

What are the types of schwannomatosis?

There are six types of schwannomatosis identified by the genetic variant that causes each one:

• NF2-related schwannomatosis (formerly known as neurofibromatosis type 2).
• SMARCB1-related schwannomatosis.
• LZTR1-related schwannomatosis.
• 22q-related schwannomatosis.
• Schwannomatosis not otherwise specified (NOS).
• Schwannomatosis not elsewhere classified (NEC).

How rare is schwannomatosis?

Schwannomatosis is the rarest type of neurofibromatosis. The exact rate of occurrence varies. Studies estimate that NF2-related schwannomatosis may affect an estimated 1 in 30,000 people and all remaining types affect 1 in 70,000 people.

Schwannomatosis only affects a small number of people who develop schwannoma tumors. It’s more common to have a single schwannoma tumor than multiple schwannomas, as with schwannomatosis.

What are the symptoms of schwannomatosis?

The most common symptom of schwannomatosis is pain. This happens when schwannoma tumors press on your nerves and surrounding tissue.

The pain might be:

• Long-lasting (chronic).
• Mild to severe.
• In any area of your body (not just where the tumor resides).
• More intense over time.

Other symptoms of schwannomatosis vary based on the tumor location. These may include:

• Numbness or a tingling sensation.
• Muscle weakness or loss of muscle function.
• Lumps or bumps (where tumors form) under your skin.

When do symptoms of schwannomatosis appear?

Studies show that symptoms of schwannomatosis usually start after age 20 and before age 40. But symptoms may appear at any age.

What causes schwannomatosis?

A genetic variant (mutation) of the NF2, SMARCB1 or LZTR1 gene causes schwannomatosis. These happen on chromosome 22.

These genes act as tumor suppressors. They regulate how often cells grow and divide. If a genetic change happens to a tumor suppressor gene, your cells don’t have the instructions they need to regulate cell growth. This leads to cells growing and dividing uncontrollably too often, which is how tumors form.

Some cases of schwannomatosis have an unknown cause where there isn’t a known or identified gene variant.

Is schwannomatosis hereditary?

Some cases of schwannomatosis are hereditary. An estimated 15% to 25% of all schwannomatosis diagnoses run in biological families. These pass in an autosomal dominant pattern, where you receive one copy of the genetic variant from one of your biological parents at conception.

Most cases of schwannomatosis happen randomly, where you do not have a history of the condition in your biological family.

What are the complications of schwannomatosis?

While most schwannoma tumors are benign or noncancerous, some tumors may turn into cancer. This is rare.

Chronic pain can take a significant toll on your emotional well-being. This symptom can affect your ability to function and feel like yourself. As a result, you may experience symptoms of depression and anxiety. Many people find it helpful to talk with a mental health professional.

How is schwannomatosis diagnosed?

A healthcare provider will diagnose schwannomatosis after a physical exam and testing. During the exam, your provider will learn more about your symptoms and your family medical history.

Because symptoms of schwannomatosis look similar to other conditions and the source of pain may be difficult to find, a schwannomatosis diagnosis may not happen immediately. Fortunately, healthcare providers use updated diagnostic criteria to make diagnosing schwannomatosis types easier than ever before. The diagnostic criteria for SMARCB1-related schwannomatosis include one of the following:

• At least one schwannoma tumor and a confirmed genetic variant of the SMARCB1 gene collected from a blood or saliva genetic test.
• At least two schwannoma tumors that have the SMARCB1 genetic variant when biopsied.

What tests diagnose schwannomatosis?

Imaging tests like an MRI can help your provider find schwannoma tumors. If your provider finds a tumor on an imaging test, they’ll order a biopsy to remove a sample of the tumor to examine it under a microscope. In addition, a genetic blood test can identify if you have a gene change that causes each type.

How is schwannomatosis treated?

There’s no cure for schwannomatosis. Treatment focuses on managing symptoms.

Your healthcare provider might recommend taking medications to relieve pain. These vary based on the location and severity of your pain.

Your provider may consider surgical removal of schwannoma tumors or clinical trials (tests on people) if you have severe pain that doesn’t get better with medications. Your provider will assess whether these are safe options for you. Possible risks of surgery include nerve damage and the chance that tumors may grow back after removal.

What is the prognosis for schwannomatosis?

Your prognosis varies based on the size, quantity and location of schwannoma tumors in your body. You may have several tumors or very few. Tumors might exist in only one part of your body or many different parts. Symptoms vary from person to person.

The most identifiable symptom of schwannomatosis is chronic pain. It can be challenging to live with pain, especially if it’s severe. Pain can impact your mental and physical health. Talk to a healthcare provider if symptoms of schwannomatosis make you feel depressed or unable to meet personal or social commitments. You may find comfort in speaking to a mental health professional.

Treatment is available to help you manage symptoms. Many people see symptom improvement after taking medications. Others might need surgery to remove the tumors. There’s a risk that tumors could grow back after removal.

What is the life expectancy of a person with schwannomatosis?

Schwannomatosis doesn’t directly affect your life expectancy. If you’re concerned about your outlook, you should speak directly with your healthcare provider. Your situation is unique, so they can give you the most up-to-date information about your case.

When should I see a healthcare provider?

Visit a healthcare provider if you experience symptoms like pain and muscle weakness with an unknown cause. Always contact a provider if you notice any unusual lumps or bumps on your body.

If you have schwannomatosis and your symptoms change or get more intense, let your provider know.

What questions should I ask my healthcare provider?

• What can I do to manage pain?
• Are there alternatives to pain medication?
• Do I need surgery?
• What are the side effects of treatment?
• Will my future children inherit this condition?