Monoclonal gammopathy associated with multiple sclerosis.

A 52-year-old white male with a 26 year history of multiple sclerosis developed a monoclonal gammopathy of the IgA class, with reciprocal depression of normal immunoglobulins. A bone marrow aspirate and biopsy showed a marked increase in plasma cells, many of which appeared immature. These findings fulfilled the diagnostic criteria for multiple myeloma. The association of multiple myeloma with multiple sclerosis may not be coincidental. Mechanisms regarding this association are discussed.