Tumors of almost any type can form along peripheral nerves. Most commonly, these are entirely benign tumors that do not metastasize to other parts of the body. Generally slow growing, these tumors can form within the substance of the nerve itself, and cause the nerve to gradually expand. Untreated nerve tumors begin to compress the adjacent nerve fibers, causing nerve dysfunction. Patients may experience pain, numbness, and/or weakness in the distribution of the affected peripheral nerve.
In almost all cases surgical excision to obtain a diagnosis and to cure the tumor is indicated. It is important to have an experienced peripheral nerve surgeon perform this operation, as most peripheral nerve tumors form within the nerve itself, and thus are surrounded and intertwined with functional nerve fibers that must at all costs be preserved during removal of the tumor.
In very few cases, the tumor is so involved with the peripheral nerve that complete excision is impossible without sacrificing the nerve. Generally your peripheral nerve surgeon will be able to tell from your MRI scan whether this is likely to be the case before the surgery is performed.
Malignant peripheral nerve tumors are rare, but do occur. There is often no way to tell for sure pre-operatively if a tumor is malignant. Pathological analysis of tumor tissue obtained via open surgery is the only way to know for sure if a tumor is malignant.
Some physicians (who are invariably not peripheral nerve surgeons) are tempted to perform needle biopsies of nerve tumors. This unfortunate procedure often not only fails to obtain diagnostic tissue, it almost uniformly damages the normal nerve fibers that surround the nerve tumor tissue. Thus, the procedure is not only useless, but it can cause irreparable weakness, numbness, and horrific neuropathic pain.