Schwannoma: a tumor of the tissue that surrounds nerves of the peripheral nervous system, medically known as the nerve sheath. The name schwannoma comes from the cell of origin (Schwann cell) that makes up the tissue around the nerves. Schwannomas are usually benign (not cancerous), but rarely may be malignant.
An acoustic neuroma (vestibular schwannoma) is a common type of schwannoma that develops on the nerve that connects the ear to the brain. A schwannoma may not cause any symptoms. In other cases, the symptoms depend on the location and size of the growth. The symptoms can include a lump or bump that can be felt, pain, tingling, numbness, hearing problems, or facial paralysis. The cause of schwannomas is poorly understood. Some people with genetic disorders such as neurofibromatosis 2 (NF2), schwannomatosis, or Carney complex may develop multiple schwannomas.