Polyneuropathy in Waldenström's macroglobulinemia. Deposition of M component on myelin sheaths

A chronic sensory neuropathy was the initial symptom in a case of Waldenström's macroglobulinemia in a 53-year-old woman. Ultrastructural analysis of a biopsied peripheral nerve revealed a modification of the lamellar structure of the myelin sheath. Immunofluorescent microscopy showed IgM-positive deposits on the myelin sheath. The monoclonal globulin (M component) present in the myelin appears to be a causative factor in the neuropathy.