Heavy- and free light-chain myeloma associated with peripheral polyneuropathy

Peripheral polyneuropathy, a rare complication of multiple myeloma, is generally associated with heavy-chain M-proteins and, in very rare instances, with free light-chain myeloma proteins. Here we describe a case of multiple myeloma and polyneuropathy with both monoclonal IgG and free lambda light chains in the blood. The patient also had free lambda light chains in the cerebrospinal fluid and urine.