Pauci-immune necrotizing crescentic glomerulonephritis is the pattern of injury most commonly seen with ANCA-associated glomerulonephritis. This may present as granulomatosis with polyangiitis (GPA, formerly known as Wegener granulomatosis), microscopic polyangiitis (MPA), eosinophilic granulomatosis with polyangiitis (EGPA, formerly Churg-Strauss syndrome), or be renal limited. More than 85% of patients with active disease have positive ANCA. The kidney manifestations are indistinguishable in these entities, and most patients present with systemic vasculitis and rapidly progressive glomerulonephritis.