Sulfasalazine induced lupus in rheumatoid arthritis

We describe 2 cases of a lupus syndrome induced by sulfasalazine in rheumatoid arthritis. All symptoms resolved and antihistone antibodies disappeared when sulfasalazine was discontinued. In one patient, perinuclear antineutrophil cytoplasmic antibodies with specificity for myeloperoxidase were found critically increased just before the occurrence of vasculitis.