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# ANCA-associated vasculitis

- Lesion

Antibodies against neutrophil enzymes make neutrophils attack small vessels, mainly in the lungs, airways and kidneys.

Updated Nov 12, 2026

## Key points

- GPA: triad of upper airway (sinusitis, nasal ulcers, saddle nose), lungs (nodules, cavities) and kidneys (necrotizing crescentic glomerulonephritis); PR3-ANCA (c-ANCA) in most.
- MPA: lung capillaritis with hemorrhage and glomerulonephritis; all lesions the same age; MPO-ANCA (p-ANCA); can follow drugs.
- EGPA: asthma, allergic rhinitis, blood eosinophilia, neuropathy and heart involvement; MPO-ANCA in about half, more when the kidney is involved.
- Infections and drugs (for example hydralazine, propylthiouracil, levamisole-adulterated cocaine) can induce ANCA.
- Kidney: pauci-immune crescentic glomerulonephritis, a cause of rapidly progressive glomerulonephritis.

## What it is

Antineutrophil cytoplasmic antibodies (ANCA) bind proteinase 3 (PR3) or myeloperoxidase (MPO) on cytokine-primed neutrophils, which then degranulate and damage small vessels. The lesions contain little immunoglobulin (pauci-immune). Granulomatosis with polyangiitis (GPA) adds necrotizing granulomas of the airways; microscopic polyangiitis (MPA) has vasculitis without granulomas; eosinophilic GPA (EGPA) adds asthma, eosinophilia and eosinophil-rich granulomas.

## Structure

- GPA lung: large nodules with geographic necrosis, palisading histiocytes, giant cells and necrotizing vasculitis; may cavitate.
- Kidney in all three: segmental fibrinoid necrosis of glomerular capillaries with crescents and little or no immunofluorescence staining.

## Step by step

- An infection or other inflammatory trigger primes neutrophils, which move PR3 or MPO to their surface.
- ANCA bind these antigens and activate the neutrophils.
- Activated neutrophils release proteases, oxidants and neutrophil extracellular traps onto the endothelium.
- Small vessels undergo fibrinoid necrosis; in GPA granulomas form around necrosis.
- Damage appears in lung, airway and glomeruli; healing leaves scars and crescents.

## The three ANCA-associated vasculitides

| Disease | Antibody | Distinctive histology | Typical organs |
| --- | --- | --- | --- |
| [Granulomatosis with polyangiitis](https://durgical.com/en/conditions/granulomatosis-with-polyangiitis/) | PR3-ANCA in most | Necrotizing granulomas with geographic necrosis plus vasculitis | Nose and sinuses, lungs, kidneys |
| [Microscopic polyangiitis](https://durgical.com/en/conditions/microscopic-polyangiitis/) | MPO-ANCA | Fibrinoid necrosis of capillaries and venules, no granulomas | Kidneys, lung capillaries, skin |
| [Eosinophilic granulomatosis with polyangiitis](https://durgical.com/en/conditions/eosinophilic-granulomatosis-with-polyangiitis/) | MPO-ANCA in about half | Eosinophil-rich infiltrates and granulomas | Airways (asthma), nerves, heart, skin |

## Clinical notes

- Untreated GPA is usually fatal; immunosuppression induces remission in most, and PR3-ANCA levels help follow relapses.
- Lung hemorrhage with acute kidney injury (pulmonary–renal syndrome) suggests ANCA vasculitis or anti-GBM disease.

## Memory aid

PR3 likes granulomas in the nose; MPO prefers clean small vessels; add asthma and eosinophils and you have Churg–Strauss.

## Test yourself

Think of the answer, then tap the question to see it.

## Which three sites form the classic triad of granulomatosis with polyangiitis?

The upper airway (nose, sinuses), the lungs and the kidneys.

## Which ANCA vasculitis lacks granulomas?

Microscopic polyangiitis.

## Which clinical features suggest eosinophilic GPA?

Asthma, allergic rhinitis, blood eosinophilia, lung infiltrates, neuropathy and often heart involvement.

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## Elsewhere in DurgiPedia

- [Autoantibodies: the table to know](https://durgical.com/en/immunology/autoantibodies-the-table-to-know/)
- [Neutrophil](https://durgical.com/en/immunology/neutrophil/)
- [Granulomatous inflammation](https://durgical.com/en/immunology/granulomatous-inflammation/)

## Connections

## Related 6

- [Vasculitis: classification and mechanisms](https://durgical.com/en/general-pathology/vasculitis-classification-and-mechanisms/)
- [Immune-complex small-vessel vasculitis](https://durgical.com/en/general-pathology/immune-complex-small-vessel-vasculitis/)
- [Granulomatous inflammation: caseating vs non-caseating, the causes to know](https://durgical.com/en/general-pathology/granulomatous-inflammation-caseating-vs-non-caseating-the-causes-to-know/)
- [Necrotizing lesions of the nose and upper airway](https://durgical.com/en/general-pathology/necrotizing-lesions-of-the-nose-and-upper-airway/)
- [Diffuse alveolar hemorrhage](https://durgical.com/en/general-pathology/diffuse-alveolar-hemorrhage/)
- [Pulmonary eosinophilia](https://durgical.com/en/general-pathology/pulmonary-eosinophilia/)

## Related conditions 5

- [Granulomatosis with polyangiitis](https://durgical.com/en/conditions/granulomatosis-with-polyangiitis/)
- [Microscopic polyangiitis](https://durgical.com/en/conditions/microscopic-polyangiitis/)
- [Eosinophilic granulomatosis with polyangiitis (Churg–Strauss)](https://durgical.com/en/conditions/eosinophilic-granulomatosis-with-polyangiitis/)
- [Rapidly progressive glomerulonephritis (anti-GBM, ANCA)](https://durgical.com/en/conditions/rapidly-progressive-glomerulonephritis/)
- [Asthma](https://durgical.com/en/conditions/asthma/)

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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Granulomatosis with polyangiitis: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000135.htm) (MedlinePlus, US National Library of Medicine, 2025); [Vasculitis| Angiitis | MedlinePlus](https://medlineplus.gov/vasculitis.html) (MedlinePlus, US National Library of Medicine, 2025).

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