BLOOD-NERVE BARRIER IN IGM PARAPROTEINEMIC NEUROPATHY - A CLINICOPATHOLOGICAL ASSESSMENT

We report the pathologic findings in a patient with sensorimotor neuro pathy associated with Waldenstrom's macroglobulinemia, particularly in relation to blood-nerve barrier defects. The monoclonal IgM was of ka ppa type and possessed anti-HNK-1 activity. A suraI nerve biopsy speci men revealed severe loss of myelinated and unmyelinated nerve fibers a nd gaps between adjacent endothelial cells of small endoneurial vessel s, Postmortem findings 3 years later included severe loss of myelinate d nerve fibers and diffuse infiltration by lymphoplasmacytic B cells t hroughout the peripheral nervous system, sparing the central nervous s ystem. Findings in this case suggest an immune attack against endoneur ial endothelial cells with permeation of IgM into peripheral nerve tis sue.