Are monoclonal gammopathies in rheumatoid arthritis predictive for lymphoproliferative disorders?

There is limited evidence for the association of specific malignancies with rheumatoid arthritis (RA). Monoclonal gammopathies can occur in RA. Their predictive value for the development of a lymphoproliferative disorder remains unclear and disputed. We reviewed charts of 214 RA patients all of whom had at least one serum protein electrophoresis. We performed a retrospective study of 12 patients with RA and an M spike. We further characterized the M spike by serum immunofixation and bone marrow studies. The median age at which the M spike was identified was 69 years. IgG was the predominant gammopathy in 50% of patients, with no difference in the amount of kappa (kappa) and lambda (lambda) chains. One patient was diagnosed with multiple myeloma, one with an undefined primary lymphoproliferative disorder, one with T-cell leukemia, five with myelodysplastic syndrome, and four with monoclonal gammopathy of undetermined significance at most recent evaluation. Of our patients, 42% had a myelodysplastic syndrome, which has not been previously reported, and, in contrast to previous reports, no lymphomas were identified. The follow-up evaluation of patients with myelodysplastic syndrome and monoclonal gammopathy of undetermined significance is important because they may progress to an overt neoplasia.