Anti-neutrophil cytoplasmic antibody (ANCA) - associated vasculitides refer to a group of heterogeneous autoimmune diseases characterized by necrotizing vasculitides and positive ANCA titers. They are reactive to either proteinase-3 (PR3-ANCA) - cANCA or myeloperoxidase (MPO-ANCA) - pANCA. These vasculitides affect arterioles, capillaries, and venules which can involve virtually any organ with varying degrees of severity. As a general rule, the lungs and kidneys are the most commonly involved.
The conditions that fall into this group are:
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granulomatosis with polyangiitis
- positive to cANCA in about 90% of cases
- granulomatous
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microscopic polyangiitis
- positive to pANCA in about 50-90% of cases
- non-granulomatous
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idiopathic pauci-immune pulmonary capillaritis
- sometimes classified as a subset of microscopic polyangiitis
- may or may not be positive to pANCA
- non-granulomatous
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idiopathic pauci-immune rapidly progressive glomerulonephritis (RPGN)
- sometimes classified as a subset of microscopic polyangiitis
- may or may not be positive to pANCA
- non-granulomatous
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eosinophilic granulomatosis with polyangiitis
- positive to pANCA in about 35-75% of cases
- granulomatous