The coexistence of rheumatoid arthritis and systemic lupus erythematosus: a case report and review of the literature.

We describe a patient with longstanding classical erosive rheumatoid arthritis (RA), who after many years developed the clinical and serological manifestations of systemic lupus erythematosus (SLE) including diffuse proliferative lupus nephritis. She fulfilled the ARA preliminary criteria for the classification of SLE as well as the ARA criteria for classical RA. In addition she had antibodies to native DNA, hypocomplementemia, and deposits of immunoglobulins at the dermal-epidermal junction of the non-lesional skin. The rarity of the concurrence of these 2 diseases in the same patient and the discriminating findings with tissue typing analysis suggest that this coexistence may be coincidental.