ANCA-related crescentic glomerulonephritis in systemic sclerosis: revisiting the "normotensive scleroderma renal crisis".

The scleroderma renal crisis is characterized by acute onset of severe hypertension and by rapidly progressive hyperreninemic renal failure. There is, however, a very limited subset of patients with rapidly progressive renal failure who remain normotensive and develop ANCA-positive crescentic glomerulonephritis. We report a case of normotensive acute renal failure secondary to anti-MPO antibody-associated crescentic glomerulonephritis in a patient with diffuse systemic sclerosis. She was referred to our department with normal blood pressure and no extrarenal clinical manifestation ofvasculitis. She presented with rapidly progressive renal failure, microscopic hematuria and minimal proteinuria. P-ANCA were positive by immunofluorescence, with ELISA-confirmed specificity for myeloperoxidase. Renal biopsy revealed typical features of pauciimmune glomerulonephritis with crescent formation and fibrinoid necrosis. The patient was initially treated with i.v. cyclophosphamide only. Because of ongoing deteriorating renal function, additional treatment with intravenous pulses of methylprednisolone followed by oral prednisone was started and allowed renal function improvement. After 9 months, serum creatinine had almost returned to normal level with minimal proteinuria, no hematuria and negative ANCA testing. Control kidney biopsy only revealed scar lesions. The association of ANCA-positive crescentic glomerulonephritis and systemic sclerosis is a very rare event. Treatment with intravenous cyclophosphamide and corticosteroids allows rapid and long-term improvement of renal function. The onset of typical scleroderma renal crisis triggered by high-dose corticosteroids is unlikely but requires a close follow-up of patients with overlapping systemic sclerosis. Diagnosis and treatment are discussed and previously published cases are reviewed.