Your peripheral nerves link your brain and spinal cord to other parts of your body. These nerves control your muscles so that you can walk, blink, swallow, pick things up and do other activities.

Several types of nerve tumors occur. Though their cause is usually unknown, some are hereditary.

Most tumors aren't cancerous (malignant), but they can lead to nerve damage and loss of muscle control. That's why it's important to see your doctor when you have any unusual lump, pain, tingling or numbness.

  • Experience. Every year, Mayo Clinic doctors treat more than 500 people with benign peripheral nerve tumors.
  • Expertise. Mayo Clinic has earned national recognition for developing special techniques that let surgeons remove a tumor, often without damaging nerves.
  • Team approach. To diagnose and treat people who have benign peripheral nerve tumors, integrated teams of doctors, including neurologists and neurosurgeons, work with doctors trained in inherited conditions (geneticists) and professionals trained to help people regain movement and function.

Mayo Clinic in Rochester, Minn., ranks #1 for neurology and neurosurgery in the U.S. News & World report Best Hospitals rankings. Mayo Clinic in Rochester, Minn., is ranked among the Best Hospitals for rehabilitation by U.S. News & World Report.

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Peripheral nerve tumors affect nerves by growing within them (intraneural tumors) or by pressing against them (extraneural tumors). Most are benign.

Intraneural tumors

  • Nerve sheath tumors. This type includes schwannomas and neurofibromas, tumors that form within the nerve. Most are round and small. Others may enlarge and assume unusual shapes within your spine or pelvis, such as dumbbell tumors.

    Your Mayo Clinic treatment team is experienced in removing all of these tumors, from the routine to the more challenging type.

  • Schwannoma. The most common benign peripheral nerve tumor in adults, a schwannoma, can occur anywhere. It typically comes from a single bundle (fascicle) within the main nerve and displaces the rest of the nerve.

    When a schwannoma grows larger, more fascicles are affected, making removal more difficult. In general, they grow slowly.

    If you develop a schwannoma in an arm or leg, you may notice a mass. If you have a rare schwannoma near your brain stem (an acoustic neuroma), you may notice trouble with your balance or hearing. Most of the time this type of tumor forms without being associated with a syndrome, but a few acoustic neuromas may be diagnosed as NF2 tumors.

  • Schwannomatosis. Schwannomas most commonly occur as solitary tumors, though occasionally individuals may have several of them in the arms, legs or body, a condition known as schwannomatosis.
  • Neurofibromatosis 2 (NF2). If you develop acoustic neuromas on both sides of the brain, a rare event, you may notice progressive hearing loss, poor balance, headaches, facial pain or numbness. Untreated NF2 tumors that continue to grow can affect nearby nerves, including the brainstem, and cause death.
  • Neurofibroma. This common type of benign nerve tumor tends to form more centrally within the nerve. A neurofibroma may arise from several nerve bundles and tends to cause mild symptoms. This tumor most commonly develops in people who have neurofibromatosis 1 (NF1).

    Doctors usually diagnose people who have NF1 by examining discolorations or benign tumors on their skin. Some people who have NF1 may develop other conditions, such as curvature of the spine (scoliosis), another bone deformity or an eye nerve tumor (optic glioma).

  • Perineurioma. This rare benign peripheral nerve tumor can also develop as an extraneural tumor. It occurs most commonly in children and young adults and typically causes gradually progressive weakness and sensory loss involving an arm or leg.

Extraneural tumors

  • Lipomas. Slow-growing fat cells cause these benign, soft lumps that usually appear under the skin on the neck, shoulders, back or arms. A lipoma near a nerve may compress it. Usually, though, they cause no pain or other problems. Your doctor may want to monitor it through regular checkups.
  • Ganglion cysts. Some of these cysts come from an injury, but most have no known cause. They commonly form around joints, such as your wrist, and can cause pain and interfere with everyday activities. Some go away without treatment, but ganglion cysts that compress neighboring nerves should be removed.

Your Mayo Clinic doctor will diagnose your condition based on a detailed physical examination and a discussion with you about your medical history. If signs suggest that you could have a benign peripheral nerve tumor, your doctor may recommend one or more of these diagnostic tests:

  • Magnetic resonance imaging (MRI). This scan uses a magnet and radio waves to produce a detailed, 3-D view of your nerves and surrounding tissue.
  • Computerized tomography (CT). A CT scanner rotates around your body to record a series of images. A computer uses the image to make a detailed view of your peripheral nerve tumor so that your doctor can evaluate how it may be affecting you.
  • Electromyogram (EMG). For this test, your doctor places small needles in your muscles so an electromyography instrument can record the electrical activity in your muscle as you try to move it.
  • Nerve conduction study. You're likely to have this test along with your EMG. It measures how quickly your nerves carry electrical signals to your muscles.
  • Tumor biopsy. If imaging tests identify a nerve tumor, your doctor may remove and analyze a small sample of cells (biopsy) from your tumor. Depending on the tumor's size and location, you may need local or general anesthesia during the biopsy.
  • Nerve biopsy. If you have a condition such as a progressive peripheral neuropathy or enlarged nerves that mimic nerve tumors, your doctor may take a nerve biopsy.

If your peripheral nerve tumor is benign, your Mayo Clinic doctor will recommend either observation or surgery.

Your doctor may recommend observation if your tumor is in a place that makes removal difficult or if the tumor is small and causes no problems. Observation includes regular checkups and imaging tests to see if your tumor is growing.

More commonly, your doctor will recommend surgery to remove the tumor. After surgery, you may need physical rehabilitation. Your doctor may use a brace or splint to keep your arm or leg in a position that helps you to heal.

If you're having pain, your doctor may prescribe a pain medication or recommend an over-the-counter drug such as ibuprofen (Advil, Motrin IB, others) or aspirin.

Mayo Clinic physical therapists and occupational therapists can guide you through specific exercises that keep your muscles and joints active, prevent stiffness, and help to restore your function and feeling.

Mayo Clinic works with hundreds of insurance companies and is an in-network provider for millions of people. In most cases, Mayo Clinic doesn't require a physician referral. Some insurers require referrals or may have additional requirements for certain medical care. All appointments are prioritized on the basis of medical need.

At Mayo Clinic's campus in Arizona, doctors trained in diagnosing and treating conditions of the nervous system, including neurologists and neurosurgeons, work with doctors trained in hereditary conditions (geneticists) and specialists trained in rehabilitation to evaluate and treat people who have benign peripheral nerve tumors at Mayo Clinic's campus in Arizona.

For appointments or more information, call the Central Appointment Office at 800-446-2279 (toll-free) 8 a.m. to 5 p.m. Mountain Standard Time, Monday through Friday or complete an online appointment request form.

At Mayo Clinic's campus in Florida, doctors trained in surgery on the bones, joints, ligaments, tendons, muscles and nerves (orthopedic surgeons) work with doctors trained in surgery of the spine, nerves and other parts of the nervous system (neurosurgeons) and specialists trained in rehabilitation to diagnose and treat adults who have peripheral nerve tumors.

For appointments or more information, call the Central Appointment Office at 904-953-0853 8 a.m. to 5 p.m. Eastern time, Monday through Friday or complete an online appointment request form.

At Mayo Clinic's campus in Minnesota, doctors trained in diagnosing and treating conditions of the nervous system (neurologists and neurosurgeons) work with doctors trained in hereditary conditions (geneticists) and specialists trained in rehabilitation to evaluate and treat children and adults who have benign peripheral nerve tumors.

For appointments or more information, call the Central Appointment Office at 507-538-3270 7 a.m. to 6 p.m. Central time, Monday through Friday or complete an online appointment request form.

Occasionally, children and adolescents get some type of nerve tumor. Mayo Clinic treatment teams in Minnesota have experience treating tumors and will make appropriate recommendations. Your child's treatment team can include doctors trained in treating conditions of the brain, muscles and nerves, including pediatric neurologists and neurosurgeons, doctors trained in hereditary conditions (geneticists), and specialists trained in rehabilitation.

For appointments or more information, call the Central Appointment Office at 507-538-3270 7 a.m. to 6 p.m. Central time, Monday through Friday or complete an online appointment request form.

See information on patient services at the three Mayo Clinic locations, including transportation options and lodging.

Mayo Clinic researchers have a long history of developing innovative treatments for many kinds of tumors.

Read more about benign peripheral nerve tumors research at Mayo Clinic.

See a list of publications about benign peripheral nerve tumors by Mayo Clinic doctors on PubMed, a service of the National Library of Medicine.

Oct. 11, 2014