Clinical meaning
Pulmonary vasculitis involves inflammation and destruction of blood vessel walls in the lungs, mediated by autoantibodies (ANCA), immune complexes, or T-cell-mediated mechanisms. In granulomatosis with polyangiitis (GPA), anti-PR3 antibodies (c-ANCA) activate neutrophils that infiltrate vessel walls, causing necrotizing granulomatous inflammation. In microscopic polyangiitis (MPA), anti-MPO antibodies (p-ANCA) cause pauci-immune capillaritis. The damaged vessels allow blood and inflammatory exudate to leak into alveoli, causing diffuse alveolar hemorrhage, while granuloma formation can cavitate and destroy lung parenchyma.
Exam relevance
Risk factors: - Granulomatosis with polyangiitis (GPA/Wegener) - Microscopic polyangiitis (MPA) - Eosinophilic granulomatosis with polyangiitis (EGPA/Churg-Strauss) - Systemic lupus erythematosus - Behcet disease - Drug-induced vasculitis (hydralazine, propylthiouracil) - Age 40-65 years (peak incidence)
Diagnostics: - ANCA panel: c-ANCA/PR3 (GPA), p-ANCA/MPO (MPA) - CT chest showing nodules, cavitary lesions, or ground-glass opacities - Urinalysis for hematuria and proteinuria (renal involvement) - Serum creatinine and GFR (renal vasculitis assessment) - Tissue biopsy (lung, kidney, or sinus) showing necrotizing vasculitis - ESR and CRP (elevated, nonspecific)