Monoclonal gammopathy in systemic lupus erythematosus.

In order to ascertain the incidence of monoclonal gammopathy (MG) in systemic lupus erythematosus (SLE), 120 SLE patients were evaluated. Four patients (3.3%), two of whom were under 50 years of age, were found to have a monoclonal immunoglobulin in their serum. Our data agree with the previous literature in demonstrating a higher incidence of MG in SLE patients in comparison with the general population. Neither the clinical importance nor the pathogenetic significance of this association is known.