Development of MPO-ANCA-related Vasculitis in Systemic Sclerosis: Report of Two Cases and Review of the Literature

Abstract

We report two patients, a 59-year-old female and a 21-year-old female with systemic sclerosis (SSc) who demonstrated myeloperoxidase-antineutrophil cytoplasmic antibodies (MPO-ANCA). Both patients developed crescentic glomerulonephritis and mononeuritis multiplex, respectively, nine years after the onset of SSc. We diagnosed these patients as having an overlap of SSc and MPO-ANCA-related vasculitis. A combination of oral administration of prednisolone and intravenous cyclophosphamide improved their vasculitic symptoms. We determined the incidence of ANCA-related vasculitis in SSc patients at our hospital. Of the 21 SSc patients examined, only the two patients described here were MPO-ANCA positive. A literature review demonstrated that the features of Japanease SSc patients who produce MPO-ANCA included a high incidence of positive anti-topoisomerase I antibody (71%) and a long lag phase between the onset of SSc and the development of MPO-ANCA (average 10 years, 0.5～30 years). Although the development of MPO-ANCA-related vasculitis is extremely rare in SSc patients, it is clinically of great importance. Acute progressive glomerulonephritis as well as pulmonary hemorrhage caused by ANCA-related vasculitis can determine the prognosis of such patients. If clinically evident vasculitis occurs in an SSc patient, particularly a patient with positive anti-topoisomerase I antibody and a long lag phase from the onset of SSc, prompt diagnosis of ANCA-related vasculitis and the early initiation of immunosuppressive therapy, particularly in the case of life-threatening conditions, can be determinative factors for a good outcome.