Snapshot A 55-year-old man presents to the emergency department due to coughing up blood in the morning. His symptoms are accompanied by fever, arthralgias affecting the wrists and knees, and unintentional weight loss over the course of 3 months prior to presentation. The patient also noticed mild shortness of breath. On physical exam, there is mild nasal crusting and bloody nasal discharge. There are no lesions in the mouth. There is tenderness to palpation of the wrist and knees. Laboratory testing is significant for an elevated erythrocyte sedimentation rate, C-reactive protein, and a creatinine of 2.5 mg/dL (his creatinine is normally 0.9 mg/dL). A radiograph of the chest demonstrates pulmonary nodules. Introduction Clinical definition small- to medium-sized vessel vasculitis and granulomatosis that affects upper and lower respiratory tract and kidneys previously known as Wegener granulomatosis Epidemiology incidence can occur at any age but typically between 65-75 years of age Etiology unclear but may involve both genetic and environmental components Pathogenesis antiproteinase-3 (PR3 ANCA/c-ANCA) antibodies present in ~95% of cases T-cell mediated hypersensitivity reaction that leads to granuloma formation Associated conditions rapidly progressive glomerulonephritis Prognosis glucocorticoids can lead to remission at 6 months in > 90% of patients Presentation Symptom/physical exam upper respiratory symptoms sinusitis (most common) recurrent otitis media otalgia lower respiratory symptoms hemoptysis renal symptoms hematuria skin leukocytoclastic angiitis Imaging Radiography indication should be performed in all patients with pulmonary involvement likely secondary to ANCA-associated vasculitis computerized tomography scan is also performed views chest findings single or multiple nodules/masses in ~66% of cases nodules may be cavitated Studies Labs ↑ C-reactive protein and erythrocyte sedimentation rate positive PR3 ANCA/c-ANCA testing Biopsy the site of active disease confirms the diagnosis demonstrates granulomas, giant cells, necrosis, and vasculitis Differential Microscopic polyangiitis differentiating factor does not present with nasopharyngeal involvement, which is seen in granulomatosis with polyangiitis no granuloma formation MPO-ANCA/p-ANCA positive Polyarteritis nodosa differentiating factor renal infarcts, artery stenosis, and visceral microaneurysms are classic for polyarteritis nodosa not associated with ANCA antibodies Treatment Medical high-dose glucocorticoids indication initial treatment option in patients with non-life or organ-threatening disease typically given with methotrexate high-dose glucocorticoids with cyclophosphamide or rituximab indication initial treatment option in patients with life- or organ-threatening disease Complications Pulmonary hemorrhage Respiratory failure Uremia Renal failure Palpable purpura and other vascular lesions