Rheumatoid arthritis complicated with myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA)-associated vasculitis: a case report.

This article describes a patient with rheumatoid arthritis (RA) with crescentic glomerulonephritis (CrGN) associated with myeloperoxidase-antineutrophil cytoplasmic antibodies (MPO-ANCA), who responded well to methotrexate (MTX). A 48-year-old woman with a 4-year history of RA was admitted with fever and elevated C-reactive protein. On laboratory evaluation, her level of MPO-ANCA was 422 EU, and urinalysis revealed proteinuria and hematuria. Because she was also suffering from episcleritis, vasculitis was considered. A renal biopsy was performed, which revealed necrotizing CrGN. We diagnosed RA complicated with MPO-ANCA-associated vasculitis. We considered treatment with high-dose oral prednisolone for vasculitis, but the patient refused this treatment. We started MTX at a dose of 8 mg/week for RA from the time of admission, and the patient responded immediately. Biochemical parameters, including C-reactive protein, erythrocyte sedimentation rate, rheumatoid factor, and MPO-ANCA, improved. Seven months later, MPO-ANCA had decreased to 46 EU. In clinical studies, few patients have been reported with RA complicated with ANCA-associated CrGN. This case differs from previous cases in the treatment given. No high-dose steroid with intensive immunosuppression or plasma exchange was required.