The term crescentic
glomerulonephritis (GN) refers to a pathologic condition characterized by extracapillary proliferation in >50% of glomeruli. Clinically crescentic GN is characterized by a nephritic syndrome rapidly progressing to
end stage renal disease (
ESRD). Three types of crescentic GN have been identified. Type 1 includes cases of
Goodpasture syndrome characterized by linear deposits of
antibodies along the glomerular basement membrane (GBM) at immunofluorescence. Type 2 is a heterogeneous group of primary or secondary glomerular diseases complicated by crescentic GN. In this category there are granular deposits of
immunoglobulins and
complement fractions on the glomerular tuft. Type 3 includes cases of
ANCA-associated small-vessel
vasculitis. Immunofluorescence is negative or may show only faint deposits of
immunoglobulins. The etiology and the initial pathogenetic factors are different in the three types, but the final mechanisms leading to crescent formation and the renal symptoms and signs are similar. The prognosis depends on the timeline of diagnosis and treatment. Although some patients requiring dialysis may recover a good renal function, usually the higher the serum
creatinine at presentation the worse the outcome. When treatment is initiated early, most patients obtain a complete or partial remission. High-dose
corticosteroids and
cyclophosphamide represent the standard
therapy for crescentic GN. The addition of
plasma exchange may also be helpful, particularly in patients with massive alveolar
hemorrhage. Anti-B
monoclonal antibodies have also been used in some patients with crescentic GN, but their role in this particular area is still poorly established.