N Engl J Med 371: 1771 - 1780, 2014. doi: 10.1056/NEJMoa1404231 Key Points In granulomatosis with polyangiitis, vasculitis affects small - and medium-sized vessels in any organ, typically the kidneys (with glomerulonephritis), and upper and lower respiratory tracts with significant necrotizing parenchymal granulomatous inflammation, which is often more striking than the vasculitis.