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[MPO-ANCA positive rapidly progressive glomerulonephritis in a patient with rheumatoid arthritis during treatment with D-penicillamine].

We present here a case of MPO-ANCA positive rapidly progressive glomerulonephritis (RPGN) after 34 months of D-penicillamine (D-PC) therapy for rheumatoid arthritis (RA). A 27-year-old Japanese woman was diagnosed as having RA in June 1994 at our out-patient clinic. Oral D-PC administration was initiated at a dose of 100 mg per day in January 1995. In August 1997, proteinuria, hematuria, renal insufficiency, and anemia developed. D-PC was withdrawn promptly, and prednisolone 5 mg per day was started. The patient was admitted to our hospital in September. On admission, anti-neutrophil cytoplasmic antibody against mycloperoxidase (MPO-ANCA) was strongly positive in the serum. Renal biopsy showed glomerulonephritis with cellular crescent formation in 60% of the glomeruli observed. Immunofluorescence examinations revealed deposits of granular IgG, IgA, C 1 q, and C 3 in the mesangium. The patient was treated with steroid pulse therapy along with administration of anti-coagulation and anti-platelet agents under the diagnosis of MPO-ANCA positive D-PC-induced RPGN. The renal function was gradually recovered and MPO-ANCA disappeared. Since RPGN is potentially a fatal disease, frequent monitoring of renal function and discontinuation of D-PC are required. In case MPO-ANCA becomes positive, prompt and correct diagnosis of the renal disorder could lead to a good prognosis as in this case. The present case may provide some important immunological insights into medical procedures to treat D-PC-induced RPGN and MPO-ANCA related glomerulonephritis.