Nerve sheath tumors

Diagnosis

To diagnose a nerve sheath tumor, your care team reviews your health history and asks about any changes you've noticed. These tumors begin in the protective covering around the nerve, called the nerve sheath, so diagnosis focuses on showing whether a growth is coming from this layer. A physical exam and a neurological exam help show how the affected area is working. Several tests can help find out whether a growth arises from the nerve and how it is behaving:

• Magnetic resonance imaging (MRI). MRI is the primary imaging test for nerve sheath tumors. It provides the clearest view of the nerve and the growth. It is often the first test you have when a nerve tumor is suspected.

  This scan uses a magnet and radio waves to create a detailed 3D view of nerves and surrounding tissue. MRI is especially helpful because it can show whether a growth arises from a nerve itself. Many nerve sheath tumors appear as smooth, well-defined masses that follow the path of a nerve. MRI can sometimes show whether a tumor is likely benign or has features that need closer review.

• Computerized tomography (CT). A CT scanner rotates around the body to capture many images. A computer combines them to show a detailed view of the growth and the structures around it.

• Electromyography (EMG) and nerve ultrasound. These tests are commonly used together to assess nerve health. EMG shows how well a nerve sends signals to muscles. Nerve ultrasound shows the nerve's structure. Together, these tests help pinpoint the affected nerve and clarify how structural changes relate to symptoms.

  Small, thin needles are placed into muscles. An instrument records electrical activity as the muscles move, which helps show whether a nerve is sending signals effectively.

  Nerve ultrasound uses sound waves to look at nerves just under the skin. The test can show nerve thickening, changes in shape or areas where a tumor may be affecting a nerve. Ultrasound also can help guide further testing or procedures in some situations.

• Nerve conduction study. Often done with an EMG, this test measures how quickly a nerve carries electrical signals to a muscle. It helps show whether a growth is slowing or blocking nerve signals.
• Tumor biopsy. A small sample of the growth is removed and examined under a microscope. Depending on its size and location, the area may be numbed or you may receive medicine that helps you sleep through the procedure. Not every nerve sheath tumor needs a biopsy. Your care team considers biopsy when imaging cannot clearly show whether the tumor is benign or cancerous. Biopsy also is done when the result would change treatment decisions.

• Nerve biopsy. In some situations, such as when a nerve keeps getting weaker or looks enlarged on imaging, a small piece of the nerve may be removed to help confirm the diagnosis.

  Imaging also helps distinguish nerve sheath tumors from other soft tissue growths, such as lipomas or cysts, which often look different on scans.

  Because experience matters when interpreting these tests and choosing the safest evaluation approach, many people benefit from working with a care team that frequently diagnoses nerve sheath tumors. Seeking a second opinion can be helpful if you want more information.

Tumor grade

Not every nerve sheath tumor is assigned a numeric grade. Instead, these tumors are placed into broad categories based on how the cells look and how quickly they grow.

A nerve sheath tumor's grade describes how quickly its cells are growing and how different the cells look from nearby tissue when checked in a lab. Grading helps the care team understand how the tumor is likely to behave and which treatment options may be most helpful.

How grading works for nerve sheath tumors

Nerve sheath tumors fall into three categories based on how the cells look under a microscope and how quickly they grow.

• Benign, also called grade 1. Schwannomas and typical neurofibromas grow slowly and look similar to nearby nerve tissue. These tumors are usually managed with monitoring or surgery if they cause symptoms.
• Atypical or intermediate grade. Atypical neurofibromas show early signs of becoming more aggressive. These tumors are watched more closely because some may get worse over time.
• High grade or malignant. Malignant peripheral nerve sheath tumors (MPNSTs) grow quickly, look very different from nearby tissue and can spread. These tumors often need more-intensive treatment because of their aggressive behavior.

Why these tumors don't use grades 1 to 4

Many cancers use a numbered grading system, but nerve sheath tumors generally do not. Benign tumors are consistently grade 1. Tumors with unusual features do not have a standard number grade. Malignant tumors are described as high grade instead of being labeled as grade 3 or grade 4.

These broader categories reflect how these tumors grow and help guide decisions about treatment.

The categories also explain why online searches for terms such as grade 2 schwannoma or grade 4 MPNST often lead to unclear or conflicting results. These labels are not part of current classification systems.

Grading versus staging

Nerve sheath tumors generally do not use a traditional cancer staging system the way many other cancers do. Benign tumors aren't staged. High-grade tumors are mainly described by grade and by whether they have spread.

Treatment

Nerve sheath tumors may be managed with surgery, stereotactic radiosurgery, cancer-directed treatments, rehabilitation or monitoring. The approach depends on the type of tumor, where it is located, and how it affects nerve function.

Surgery

Surgery is used for both benign and malignant tumors depending on size, growth and how the tumor affects nerve function. The goal is to take out the entire tumor while protecting nearby nerves and tissue. When complete removal is not possible, the care team removes as much of the tumor as they safely can.

Surgery is usually considered when the tumor is growing, affects nerve function, causes pain, or has features that raise concern for cancer. Surgery also may be advised when imaging shows that the tumor can be removed safely.

Most nerve sheath tumors are taken out with microsurgery. High-power magnification and nerve-monitoring tools help specialists separate the tumor from the nerve while preserving movement and sensation.

Risks include nerve injury and changes in how the affected area works. These risks depend on the tumor's size and location and the surgical approach. Some tumors can grow back.

Stereotactic radiosurgery

Stereotactic radiosurgery is mainly used for benign tumors located in or around the brain, such as vestibular schwannomas, especially when surgery carries higher risk. Stereotactic radiosurgery also may be considered for some malignant tumors that cannot be removed safely with surgery. It delivers a highly targeted dose of radiation to the tumor without an incision. One form of this treatment is Gamma Knife radiosurgery.

Risks may include weakness or numbness in the treated area or continued tumor growth. Very rarely, radiation exposure may lead to a new tumor in the treated region many years later.

Cancer-directed therapies

These treatments are used only for malignant peripheral nerve sheath tumors, which behave differently from benign tumors and may spread or grow more quickly. Treatment may include surgery, chemotherapy or radiation therapy. The combination used depends on the type of tumor, its location and how it responds to treatment. Cancerous tumors may return after treatment.

Rehabilitation

Rehabilitation is used after treatment for both benign and malignant tumors, especially when surgery or tumor growth affects movement, strength or sensation.

A brace or splint may be used to keep a limb in a position that supports healing. Physical therapists and occupational therapists help rebuild function, improve mobility, and teach strategies that support independence if you've lost a use of a limb or have nerve damage.

Recovery varies based on the tumor's size and location. Many people regain strength and mobility over time. Others may have lasting changes if the nerve was stretched or damaged. Most recovery occurs over weeks to months.

Monitoring and follow-up

Monitoring is an important part of care for many nerve sheath tumors. It helps track changes in tumor size and guides decisions about treatment needs. Monitoring may be used for both benign and malignant tumors, although the timing and goals differ.

Monitoring is most common for benign tumors that are small, slow growing or located in areas where treatment carries higher risk. Monitoring also may be used when the tumor is not affecting movement or sensation.

How often is monitoring needed?

Follow-up typically includes MRI, CT or ultrasound every 6 to 12 months to check for growth or changes in the tumor features. If repeat scans show that the tumor is stable, the timing of imaging may be changed to every few years.

How are malignant nerve sheath tumors monitored?

For malignant nerve sheath tumors, monitoring has different goals. Imaging may be scheduled more often to check for recurrence after treatment. Malignant tumors can return even when they are treated early, so long-term follow-up is advised.

People who have changes in movement, sensation or pain during monitoring should contact their care teams sooner. New symptoms may signal that the tumor is growing or affecting the nerve differently.

Prognosis

Prognosis for malignant nerve sheath tumors varies widely and depends on factors such as tumor size and location and whether the tumor can be removed completely. For all nerve sheath tumors, prognosis also depends on whether the tumor affects nerve function.

Benign tumors often grow slowly and may never cause serious symptoms, especially when they are small or are monitored over time. When benign tumors are removed completely, many do not return.

Some benign tumors can grow back if they cannot be removed fully without harming nearby nerves. In these situations, long-term monitoring helps track changes and guide future treatment.

Malignant nerve sheath tumors tend to grow more quickly and may spread to nearby tissue. Early diagnosis and treatment offer the best chance to control the tumor. Even after treatment, malignant tumors can return, so close follow-up is important.

Prognosis also depends on whether the tumor presses on or grows from a nerve. When nerve fibers are stretched or damaged, changes in movement or sensation may continue even after treatment. Rehabilitation may help improve strength and function over time.

Are benign nerve sheath tumors dangerous?

Most benign nerve sheath tumors grow slowly and may never cause serious symptoms. Many stay stable for years or cause only mild symptoms. Some may grow large enough to press on a nerve or nearby structures, which can affect movement or sensation. These tumors may need treatment to protect nerve function.

Can you live a typical life with a benign nerve sheath tumor?

Yes. Many people live full, active lives with benign nerve sheath tumors, especially when the tumor is small or stable over time. Monitoring helps track changes. Treatment is considered if the tumor begins to affect how the area functions.

Is a nerve sheath tumor a serious condition?

It depends on the tumor type and location. Benign tumors often have an excellent long-term outlook and may not require treatment. Malignant peripheral nerve sheath tumors grow more quickly and may spread, making early diagnosis and treatment important.

Do nerve sheath tumors come back after treatment?

Some benign tumors return if they cannot be removed completely without harming nearby nerves. Malignant tumors have a higher chance of coming back even after treatment. This is why follow-up imaging is important for both benign and malignant tumors.

How does tumor location affect prognosis?

Tumors that grow from or press on major nerves may cause lasting changes in movement or sensation, even if the tumor is treated successfully. Tumors in areas that are hard to access may require careful monitoring or staged treatment.

What is recovery like after nerve tumor removal?

Recovery varies based on tumor size and location. Many people regain strength and movement over time. But others may have lasting changes if the nerve was stretched or damaged. Most recovery occurs over weeks to months.

How fast do nerve sheath tumors grow?

Nerve sheath tumors grow at different rates depending on the tumor type. Many benign tumors grow slowly and may stay stable for years. Plexiform neurofibromas can get larger over time, especially in people with neurofibromatosis type 1. Malignant nerve sheath tumors tend to grow more quickly and may spread.

Can nerve sheath tumors metastasize?

Benign nerve sheath tumors do not metastasize. Only malignant peripheral nerve sheath tumors can metastasize. These tumors can spread to nearby tissue and sometimes to distant sites, which is why early treatment and close follow-up are important.

Coping and support

It can be stressful to deal with the possibility of nerve sheath tumor complications. Making decisions about treatment also can be hard. These suggestions may help:

• Learn as much as you can about nerve sheath tumors. The more you know, the better prepared you'll be to make choices about treatment. Besides talking with your healthcare professional, you may want to talk with a counselor or a social worker. Or you may find it helpful to talk with other people who've had a condition like yours. Ask about their experiences during and after treatment.
• Maintain a strong support system. Family and friends can be a source of support. You may find the concern and understanding of people in a support group to be especially helpful. Your healthcare professional or a social worker may be able to put you in touch with a support group.

Preparing for your appointment

If your primary healthcare professional thinks you have a nerve sheath tumor, you'll likely be referred to a specialist. Specialists include doctors who are experts in conditions of the nervous system, called neurologists, and doctors trained in brain and nervous system surgery, called neurosurgeons.

What you can do

Before the appointment, you might want to prepare a list of answers to the following questions:

• When did you first notice your symptoms?
• Have they gotten worse over time?
• Have your parents or siblings ever had similar symptoms?
• Do you have other medical conditions?
• What medicines or supplements do you take?
• What surgeries have you had?

What to expect from your doctor

Your healthcare professional may ask some of the following questions:

• Do you have pain? If so, where is it?
• Do you have any weakness, numbness or tingling?
• Have your symptoms been constant or do they come and go?
• What treatments have you tried for these symptoms?