A schwannoma is a type of nerve tumor of the nerve sheath. It's the most common type of benign peripheral nerve tumor in adults. It can occur anywhere in your body, at any age.
A schwannoma 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, a schwannoma grows slowly.
If you develop a schwannoma in an arm or leg, you may notice a painless lump. Schwannomas are rarely cancerous, but they can lead to nerve damage and loss of muscle control. See your doctor if you have any unusual lumps or numbness.
- Signs and symptoms of peripheral nerve tumors vary depending on the location of the tumors and which tissues are affected. They include:
- Dizziness or loss of balance
- Pain, tingling or numbness
- Swelling or a lump under your skin
- Weakness or loss of function in the affected area
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.