Anti-neutrophil cytoplasmic auto-antibodies-associated vasculitis with pulmonary and renal involvement.

We present a 13-year-old boy with a rapidly progressive glomerulonephritis and pulmonary haemorrhage with perinuclear anti-neutrophil cytoplasmic auto-antibodies (pANCA) corresponding to anti-myeloperoxidase antibodies. The diagnosis of microscopic polyarteritis was made on the basis of the clinical features, the positivity of pANCA, and the histological finding of a pauci-immune crescentic glomerulonephritis. He responded excellently to corticosteroids and cyclophosphamide therapy and complete clinical remission persists 1 year after withdrawal of treatment. We emphasize the usefulness of ANCA antibody assays to establish a prompt diagnosis and adequate treatment in systemic vasculitis in children.