Benign solitary tumors of the peripheral nerves

Solitary tumors of the peripheral nerves are uncommon and found to be benig n in 90 p. 100 of the cases. They develop from the elements constituting th e nerve and are generally schwannomas (80 p. 100). Other tumors are much mo re exceptional and exhibit wide histological variability. The diagnosis of a tumor of the peripheral nerve must be envisaged for all cases with tumefaction or pain on the path of a nerve exacerbated at percus sion. Magnetic resonance imaging is the preferred exploration technique, pa rticularly useful in case of a deep tumor. Preservation of nerve continuity is the underlying goal of the therapeutic strategy, irrespective of the type of tumor. Extricable tumors are to be di stinguished from inextricable tumors. Extricable tumors (schwannomas, intra nervous lipomas) displace nerve fiber bundles without penetrating into the bundle itself and can thus be resected without interrupting nerve continuit y. Prognosis is excellent if no recurrence or degeneration occurs. In case of persistent symptoms, a new exploration may be required to search for oth er localized tumor(s) unperceived at the first procedure. Inextricable tumo rs (solitary neurofibromas, hemangiomas of the Schwann sheath, neurofibroli pomas) infiltrate the structural elements of the nerve fibers making comple te excision impossible without altering the nerve fibers. Epineurotomy (ass ociated with an interfascicular biopsy for pathology examination) allows de compression and can often provide symptom relief although moderate paresthe sia may persist. Patients must be informed of this possibility prior to sur gery. Any recent and rapidly evolving modification in the clinical findings is suggestive of recurrence and should be followed by revision exploration . Malignant degeneration has not been observed in solitary tumors to our kn owledge. Our own experience with 51 cases is generally in agreement with re ports in the literature.