The coexistence of rheumatoid arthritis and systemic lupus erythematosus.

A 29-year-old white female with longstanding classical rheumatoid arthritis (RA) developed clinical and serological manifestations of systemic lupus erythematosus (SLE) with prominent signs of diffuse proliferative lupus nephritis. She fulfilled the ARA criteria for the classification of SLE as well as the ARA criteria for classical RA. The concomitant presence of these two affections in the same patient is rare and the discriminating features suggest that this coexistence may be coincidental. With respect to treatment, our patient had good relief of symptoms by a combined administration of methylprednisolone pulses and cyclophosphamide.