The symptoms and signs of a peripheral nerve tumor develop from direct effects on the main nerve or from the tumor pressing on nearby nerves, blood vessels or tissues. As the tumor grows, it may be more likely to cause signs and symptoms, although tumor size doesn't always determine effects.

Signs and symptoms of peripheral nerve tumors vary depending on the location of the tumors and which tissues are affected. They include:

• Swelling or a lump under your skin
• Pain, tingling or numbness
• Weakness or loss of function in the affected area
• Dizziness or loss of balance

It's not clear why most peripheral nerve tumors develop. Some are linked to known inherited syndromes, such as neurofibromatosis (types 1 and 2) and schwannomatosis. Others may be caused by a malfunctioning gene or triggered by injury or surgery.

Peripheral nerve tumors are more common in people who have:

• Neurofibromatosis (types 1 and 2) and schwannomatosis. In these disorders, tumors develop on or near the nerves throughout the body. These tumors, which are frequently multiple, can lead to a variety of symptoms and signs depending on their location. These tumors are usually noncancerous.
• A history of radiation treatment. If you were exposed to radiation, you are at increased risk of peripheral nerve tumors years later.

Both noncancerous and cancerous peripheral nerve tumors can compress nerves, leading to complications, some of which may be permanent:

• Numbness and weakness in the affected area
• Loss of function in the affected area
• Difficulties with balance
• Pain