Pauci-immune proliferative glomerulonephritis

**Definition:** A focal and segmental necrotising glomerulonephritis with no immune deposits (“pauci-immune”). Typical of glomerular involvement in anti-neutrophil cytoplasmic antibody (ANCA) mediated vasculitis – microscopic polyangiitis and Wegener's granulomatosis. Most but not all patients have circulation ANCA when there is active disease.