Study of five patients with myeloperoxidase anti-neutrophil cytoplasmic antibody-positive rapidly progressive glomerulonephritis during the course of interstitial pneumonitis

Abstract

Five patients with rapidly progressive glomerulonephritis (RPGN) that developed during the management of interstitial pneumonitis at our hospital in the past 5 years were studied. In these patients, chronic interstitial pneumonitis preceded the onset of nephritis by periods of 0 to 11 years. All patients had a high titer of myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) when RPGN was diagnosed. One patient had anti-proteinase-3 antibodies and another had anti-glomerular basement membrane antibodies. Renal biopsy was performed in all patients. All patients showed necrotizing and crescentic glomerulonephritis, without the deposition of immunoglobulins, and were diagnosed as having pauci immune RPGN. The relationship between MPO-ANCA-related RPGN and chronic interstitial pneumonitis remains unclear. Our present findings indicate that interstitial pneumonitis is important as a preceding condition in some patients with MPO-ANCA-related RPGN. Four patients were older than 70 years. Therefore, particular attention should be paid to the possibility of MPO-ANCA-related RPGN in elderly patients with chronic interstitial pneumonitis.