Peripheral nerve tumors

Although they’re rare, there are many kinds of peripheral nerve tumors. We bring together the specialists you’ll need to gather information and make decisions about your health care.

What is a peripheral nerve tumor?

A peripheral nerve tumor is a tumor that grows on peripheral nerves throughout the body. Peripheral nerves are the ones that branch out from the brain and spine (central nervous system). Peripheral nerve tumors are mostly benign (noncancerous). Some peripheral nerve tumors either are cancerous or can grow to become cancerous.

Benign tumors usually grow slowly and have only mild symptoms. It’s still possible for them to cause problems if they grow too big and put too much pressure on the nerves or nearby organs and tissues. When that happens, they can cause pain, damage to the nerves or other tissues, or loss of functions associated with those nerves and tissues. They can even become life-threatening if they affect important bodily functions like breathing.

Types of peripheral nerve tumor

Peripheral nerve tumors don’t fit neatly into categories. Different sources describe them differently and some even have different names for the same tumors. There are also many different types of these tumors and not much is known about some of them.

Schwannomas are the most common type of peripheral nerve tumors in adults. They’re usually benign and can occur anywhere in the body. They grow from Schwann cells, which form the myelin – a protective layer on the outside of nerves.

Vestibular schwannomas, which grow in the inner ear, are sometimes associated with brain tumors because the nerves they grow on are inside the skull and close to the brain. Some peripheral nerve tumors called neurofibromas are associated with neurofibromatosis type 1 (NF1) or neurofibromatosis type 2 (NF2). Neurofibromatosis type 1 and 2 conditions that cause tumors and other growths. Sometimes these conditions are inherited and sometimes they occur spontaneously. Most neurofibromas are benign.

Malignant peripheral nerve sheath tumors

A small percentage of neurofibromas and schwannomas can become malignant peripheral nerve sheath tumors (MPNST). These tumors are fast-growing and often grow on nerves in the legs, arms or pelvis. They can be resistant to chemotherapy treatment and often recur after treatment.

Symptoms and signs of peripheral nerve tumors

Each type of peripheral nerve tumor has its own set of symptoms, which depend on the specifics of the individual tumor such as:

• Location
• Size
• How fast it’s growing

Small, slow-growing tumors may have no symptoms or very mild symptoms. Although symptoms are different for every tumor and every person, some signs and symptoms of many peripheral nerve tumors include:

• Pain, numbness or tingling in the affected body part
• Visible lump or deformed appearance
• Loss of movement
• Fatigue
• Weakness

Diagnosis of peripheral nerve tumors

Your doctor will perform a physical exam and gather your family medical history. They’ll want to know about the duration and intensity of your potential peripheral nerve tumor symptoms. They’ll order imaging tests such as MRI, CT, PET or ultrasound based on which ones will provide better information about your potential tumor and surrounding tissues.

Your doctor is likely to recommend a surgical biopsy to confirm the diagnosis. A pathologist will examine the biopsy and provide information about the appearance of the cells to help identify the type of tumor.

Treatment for peripheral nerve tumors

Treatment depends on the location, size, type and growth rate of the tumor.

Your doctor may recommend a watchful waiting approach for a small, slow-growing tumor that isn’t likely to cause significant symptoms. You’ll have regularly scheduled checkups with imaging scans of the tumor to be sure it’s still growing slowly and not getting close to organs or tissues that would cause problems with movement, speech or other important functions.

Surgery for peripheral nerve tumors

Surgery on peripheral nerve tumors carries risks unique to the type of tumors. For example, surgery on a vestibular schwannoma needs to be done in an area that’s hard to access and may be close to the brain stem.

Any surgery on a peripheral nerve tumor requires your surgeon to be careful to avoid any damage to the nerve or surrounding tissues. It may be difficult to remove the entire tumor because of its size or location.

Surgery may be recommended for benign tumors if they’re in a place that might cause significant symptoms and it seems possible to remove all or most of the tumor.

Malignant peripheral nerve sheath tumor treatment usually includes cancer surgery to remove as much of the tumor as possible. In extreme cases, surgery for an MPNST may require partial amputation of an affected limb.

Radiation therapy and chemotherapy may be applied before surgery to shrink the tumor, after surgery to remove the rest of the tumor, or both before and after surgery.