Polyneuropathy in Waldenström's macroglobulinaemia: reduction of endoneurial IgM-deposits after treatment with chlorambucil and plasmapheresis.

A case of progressive polyneuropathy associated with Waldenström's macroglobulinaemia is reported. A monoclonal IgM-lambda gradient was detected in the serum and cerebro-spinal fluid. By electro-immunoblot analysis antibodies against myelin-associated glycoprotein were found in the serum and cerebro-spinal fluid. The motor and sensory conduction velocities of several peripheral nerves were markedly decreased, and examination of visual evoked potentials (VEPs) revealed pathological latencies. Sural nerve biopsies before and after treatment with chlorambucil and plasmapheresis showed nerve fibre loss and demyelination. In the pre-treatment biopsy, heavy accumulations of filamentous material were found which stained positively for IgM by immuno-cytochemistry. Such accumulations had disappeared in a biopsy performed after treatment. The morphological findings were correlated with an improvement of clinical and electro-physiological findings.