Wegener granulomatosis

GPA is a systemic necrotizing vasculitis involving small-to-medium vessels, classically presenting with the triad of: (1) upper respiratory tract involvement (sinusitis, saddle-nose deformity from nasal septal perforation, otitis media, oral ulcers), (2) lower respiratory tract involvement (pulmonary nodules, cavitary lesions, hemoptysis), and (3) rapidly progressive glomerulonephritis (pauci-immune, crescentic on biopsy). Serology shows c-ANCA (cytoplasmic pattern) targeting proteinase-3 (PR3-ANCA) in the majority of cases, which correlates with disease activity. Histopathology reveals necrotizing granulomas with vasculitis. Other findings can include ocular involvement (episcleritis, orbital pseudotumor), skin lesions (palpable purpura), and constitutional symptoms (fever, weight loss, arthralgias). Chest imaging often shows multiple nodules or cavitary lesions, which can mimic malignancy or infection (e.g., TB, fungal disease), making biopsy important for diagnosis. Treatment involves immunosuppression: induction therapy typically with glucocorticoids plus cyclophosphamide or rituximab, followed by maintenance therapy (azathioprine, methotrexate, or rituximab). Untreated GPA has a poor prognosis due to renal failure and pulmonary hemorrhage, but with treatment, remission rates are high. It is important to distinguish GPA from other ANCA-associated vasculitides: Microscopic polyangiitis (p-ANCA/MPO-ANCA, no granulomas, no upper respiratory involvement) and Eosinophilic granulomatosis with polyangiitis (Churg-Strauss, associated with asthma, eosinophilia, p-ANCA).