Primary malignant lymphoma of sciatic nerve. Report of a case.

A 72-year-old man with a 2-year history of motor-sensory neuropathy of the right foot was found to have a lymphoma involving a 50-cm length of the sciatic nerve. This occurred in the absence of any other evidence of disease by detailed clinical staging. The lymphoma was of large follicular center-cell type. The cells strongly expressed a B-cell marker detected by the 4KB5 monoclonal antibody and selectively infiltrated the nerve bundles, dissociating preexisting myelin-producing Schwann cells and axons. This is the second report of similar localization. Primary selective involvement of a nerve is a rare mechanism of peripheral neuropathy in lymphoproliferative disorders, to be added to systemic dissemination of lymphomas and leukemias, direct spread of an adjacent tumor, and immunologically mediated disease.