Crescentic Glomerulonephritis (Archived)

Crescentic glomerulonephritis is characterized by the presence of extensive glomerular crescents (usually greater than 50%) as the principal histologic finding. Because it often clinically presents with a rapid decline in kidney function, it is also known as rapidly progressive glomerulonephritis (RPGN). It can complicate any glomerular disease.  The disease can be primary or secondary. Primary or idiopathic crescentic glomerulonephritis is classified into the following types: Type 1 (anti-glomerular basement membrane [GBM] disease) presents with linear deposits of immunoglobulin G (IgG). Type 2 (immune-complex mediated) presents with granular deposits of immunoglobulin . Type 3 (pauci-immune) presents with few or no immune deposits, antineutrophil cytoplasmic antibody-associated small-vessel vasculitis (SVV) that may be renal-limited or part of a systemic disease, for example, granulomatosis with polyangiitis (GPA). Type 4 includes combinations of types 1 and 3. Type 5 is ANCA-negative, pauci-immune renal vasculitis (5% to 10% of cases). A crescent is made up of proliferating epithelial cells that line the Bowman capsule and infiltrating macrophages. It is a marker of severe glomerular injury. The crescents may be circumferential or noncircumferential, and the presence of circumferential crescents in over 80% of glomeruli portends a poor prognosis.