Peripheral Nerve Tumors
Peripheral nerve tumors, such as neurofibromas and schwannomas, are typically benign lesions that develop within a nerve. They are often slow growing and are discovered when the patient notices an enlarging lump. Tapping the lump will bring on pain and/or a tingling sensation downstream in the skin territory that the nerve supplies. When the tumors grow within the nerve in an area of restriction or become large, the normal fibers within the nerve become compressed. Symptoms then develop and include pain, tingling, numbness, and weakness. The treatment in some cases is periodic examination and serial imaging. In other cases, surgical removal is recommended. Despite the fact that these tumors grow within a normal nerve, they can usually be removed safely provided the treating surgeon realizes that the lump is a nerve tumor and has experience removing these tumors.
Most patients will have an isolated tumor that comes to medical attention but have no other tumors. However, in patients with genetic syndromes, such as Neurofibromatosis type 1 (NF1), Neurofibromatosis type 2 (NF2) and schwannomatosis, multiple nerve tumors will develop and grow throughout the patient’s lifetime. The tumors associated with NF1 are neurofibromas which can grow to significant size and cause pain, numbness, weakness, and disfigurement. In some cases, these are nodular and amenable to removal. In other cases, these are plexiform in shape and intimately involve the normal nerves over long lengths. These plexiform neurofibromas are much more difficult to treat. Rarely, one of these benign tumors will change into a malignant form. These usually present with a rapid enlargement, pain, and/or weakness. Treatment in that case involves removal of the malignant tumor and surrounding tissue in the hopes that the tumor will not spread to other areas of the body.
The nerve tumors associated with NF2 and schwannomatosis are called schwannomas. These do not have the same concern for malignant change, but can create problems because of growth and compression of normal structures including the brainstem, spinal cord, and nerves. They may also cause severe pain. Surgical removal is indicated when the tumor is clearly enlarging and is symptomatic.