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.