Peripheral nerve tumors affect nerves by growing within them (intraneural tumors) or by pressing against them (extraneural tumors). Most are benign.
- 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, 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 more fascicles are involved, a schwannoma grows larger, 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.
- Neurofibromatosis. 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 tumors that continue to grow can affect nearby nerves, including the brain stem, 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. Doctors usually diagnose people by examining discolorations or benign tumors on their skin. Some people 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.
- Lipomas. Slow-growing fat cells cause these benign, soft lumps that usually appear under the skin on the neck, shoulders, back or arms of people who are 40 to 60 years old. 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.
Once your benign peripheral nerve tumor has been removed, you're unlikely to have another one develop in its place or to need long-term monitoring. People who have an NF1 or NF2 tumor, however, are at risk of developing other nerve tumors and need follow-up over their lifetime.