Definition:

Rapidly progressive glomerulonephritis (RPGN) or crescentic glomerulonephritis is a life-threatening disease that destroys kidneys over a period of days to weeks. Proliferation of epithelial cells and infiltration of inflammatory cells lead to glomerular crescent formation and disruption of the specialized microvascular network in the glomerulus. This causes hematuria, albuminuria and loss of renal function. From an immunopathologic standpoint, primary RPGN is divided into pauci-immune GN (PICG), anti-glomerular basement membrane antibody (anti-GBM) GN, and immune complex GN. PIGN, the most common etiology of primary RPGN, refers to a necrotizing glomerulonephritis with few or no immune deposits by immunofluorescence or electron microscopy. Approximately 90% of patients with PICG have circulating ANCA antibodies, leading to the systemic small vessel vasculitis such as granulomatosis with polyangiitis (GPA). Corticosteroids and cyclophosphamide are the first-line treatment, but infection is the most common cause of death of RPGN patients. Several new treatment strategies, such as leukocytaphereis (LCAP) and intravenous immunoglobulin (IVIg), have become available and these treatments have made it possible to treat high-risk RPGN patients without inducing serious immunosuppressive states.