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Granulomatosis with Polyangiitis

GPA is a primary vasculitis characterized by:

  • Upper and lower respiratory tract involvement with granulomatous vasculitis of mostly small vessels, extravascular granulomatous inflammation, and necrosis
  • Glomerulonephritis that is pauci-immune, focal and segmental, necrotizing, and often crescentic
  • Strong association with c-ANCA and anti-proteinase 3 (PR3) antibodies

Generalized GPA implies involvement of all three major anatomic sites (upper respiratory tract, lungs, kidneys). Limited GPA is defined as the absence of renal involvement. Notably, limited GPA tends to present as a granulomatous disorder without vasculitic features. Only 10% of cases evolve to generalized GPA.

The true prevalence and incidence of GPA are unknown, but it is a rare disorder. It is much less common than other rheumatologic disorders. The mean age at diagnosis is 41 years. Although the age range is 5 to 78 years, only 16% of patients are <18 years of age. Males and females are equally affected.


The presence of GPA is indicated by:

- Nasal or oral inflammation (ulcers, purulent or bloody secretions).

- Abnormal chest x-ray: fixed infiltrates, nodules, caverns

- Abnormal urine sediment: haematuria or ery-cylinder

- Granulomas in biopsy in arterial wall or perivascular

GPA can be diagnosed without biopsy evidence if the following findings are present:

- Lung: fixed infiltrates (>1month), nodules or caverns; bronchial stenosis

- Oral or nasal ulcers; crusts or bloody secretions; sinusitis, otitis media, mastoiditis >3 months; retroorbital masses, saddle nose, subgottic stenosis.

- Glomerulonephritis: haematuria with ery-cylinder, >10 dysmorphic erys; 2+ haematuria or proteinuria in uristix.

- ANCA positivity

Persistent pulmonary infiltrates over 1 month are suggestive of GPA


SYNDROME

EXAMPLE

DISTINGUISHING FEATURES

Primary vasculitis syndromes

EGPA

Atopic history

Marked eosinophilia

Microscopic polyangiitis

Destructive upper airway disease unusual

Cavitary pulmonary nodules unusual

Absence of granuloma

Angiocentric immunoproliferative lesions

Lymphomatoid granulomatosis

Glomerulonephritis unusual

Pulmonary renal syndromes

Goodpasture disease

Anti-basement membrane antibodies

Immunofluorescence: linear deposition

Immune complex disease (e.g., SLE)

ANA, anti-dsDNA and Sm antibodies

Immunofluorescence: granular deposition

Granulomatous infections

Mycobacterium

Proper stains and cultures

Fungi

Actinomycosis

Syphilis

Intranasal drug abuse

Cocaine

Antineutrophil elastase antibodies

Predominantly nasal septal pathology (CIMDL)

Pseudovasculitis syndromes

Atrial myxoma

Echocardiography

Subacute bacterial endocarditis

Blood cultures

Cholesterol emboli syndrome

Echocardiography (transesophageal)

Angiography

Skin biopsy

Neoplastic

Lethal midline granuloma

Nose/palate destruction

NK T cell lymphoma

CIMDL, Cocaine-induced midline destructive lesion, which is usually associated with p-ANCA directed against human neutrophil elastase.


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