Discussion:

Systemic necrotizing vasculitis that typically involves kidneys, lung, upper aerodigestive tract.

Otologic involvement (otitis media, tympanic membrane perforation, sensorineural hearing loss, perforation of ear lobes, external otitis) as well as facial palsy occurs in 20 - 60% who have disease at traditional sites.

Vasculitis, necrosis or granulomatous inflammation (few cases have all 3).

Name changed in 2011. Was earlier called Wegener’s granulomatosis (which is a clinical diagnosis).

Triad of necrotizing angiitis, aseptic necrosis of upper respiratory tract and lungs and focal glomerulonephritis.

Likely a T cell mediated hypersensitivity reaction, the close relationship between c-ANCA titers suggests a pathogenic role.

c-ANCA likely directly activates neutrophils to release oxygen radicals and proteolytic enzymes damaging endothelium.

c-ANCA positive in 90% with active generalized disease and 60% with limited disease.

c-ANCA positive: diffuse cytoplasmic staining directed against neutrophil serine proteinase 3; can monitor course of disease with titers, ELISA test for anti-proteinase 3 now available.

p-ANCA: perinuclear staining, directed against myeloperoxidase, is usually negative, but positive in microscopic polyarteritis, inflammatory bowel disease, crescentic glomerulonephritis; ELISA test for anti-myeloperoxidase now available.