[Polyneuropathies in monoclonal gammopathy of undetermined significance: initial manifestation of a lymphoma].

BACKGROUND: Monoclonal gammopathies-including so-called monoclonal gammopathies of undetermined significance-MGUS-may cause polyneuropathies, even if immunoglobulin concentrations are within a normal range. CASE REPORT: We report on a patient with a rapidly progressive polyneuropathy with severe motor disturbances in whom a small amount of a monoclonal IgM kappa cryoglobulin was found. Only by extensive, repeatedly performed diagnostic procedures could scattered lymphoma cells be detected. Nonspecific immunosuppression had been unsuccessful but eventually a more specific chemotherapy led to an almost complete, sustained recovery.
CONCLUSION: This case shows that in patients with a polyneuropathy of uncertain etiology monoclonal immunoglobulins should be looked for and that a MGUS can precede a lymphoma. Therefore these, patients with a MGUS and clinical deterioration despite conventional immunosuppressive treatment should undergo large-scale diagnostic check-up to make sure that the chance for an adequate chemotherapy is taken.