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Granulomatosis with polyangiitis (GPA), formerly Wegener’s granulomatosis, is a systemic necrotizing granulomatous vasculitis affecting small- to medium-sized vessels, classically involving the upper and lower respiratory tracts and the kidneys.

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It is strongly associated with anti-neutrophil cytoplasmic antibodies (ANCA), especially c-ANCA (anti-PR3).

https://www.youtube.com/watch?v=3IwmGV_LJCw

https://www.youtube.com/watch?v=HSlDDGPU0Ko

Epidemiology

• Peak incidence: 4th–6th decades
• Slight male predominance
• More common in Caucasians

Pathophysiology

• Autoimmune vasculitis driven by PR3-ANCA (c-ANCA)
• Causes granulomatous inflammation of the respiratory tract and necrotizing vasculitis
• Leads to:
  • Vessel wall damage
  • Ischemia/infarction
  • Tissue destruction (especially in ENT and lungs)

Histopathology

• Necrotizing granulomatous inflammation
• Fibrinoid necrosis of small to medium vessels
• Often biopsy obtained from:
  • Nasal mucosa
  • Lung (VATS/CT-guided)
  • Kidney (crescentic glomerulonephritis)