Overview

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.

Types

Peripheral nerve tumors affect nerves by growing within them (intraneural tumors) or by pressing against them (extraneural tumors). Most are benign. Different types of benign peripheral nerve tumors include:

• 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. Some schwannomas may enlarge and assume unusual shapes within your spine or pelvis, such as dumbbell tumors. If you develop a schwannoma in an arm or leg, you may notice a mass.

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

  If you have a rare schwannoma near your brainstem (an acoustic neuroma), you may notice trouble with your balance or hearing. Also known as a vestibular schwannoma, most of the time this type of tumor forms without being associated with a syndrome, but a few acoustic neuromas may be diagnosed as neurofibromatosis 2 (NF2) tumors. Untreated NF2 tumors that continue to grow can affect nearby nerves and compress the brainstem.

  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.

• 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). Patients with NF1 are at risk of developing a malignant peripheral nerve sheath tumor.

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