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 login to view 3 more bullets Epidemiology Incidence login to view 1 more bullet Etiology Unclear but may involve both genetic and environmental components Pathogenesis login to view 2 more bullets Associated conditions login to view 1 more bullet Presentation Symptom/physical exam login to view 11 more bullets Imaging Radiography login to view 8 more bullets Studies Labs login to view 2 more bullets Biopsy the site of active disease login to view 2 more bullets Differential Microscopic polyangiitis login to view 4 more bullets Polyarteritis nodosa login to view 3 more bullets Treatment Medical login to view 7 more bullets Complications Pulmonary hemorrhage Respiratory failure Uremia Renal failure Palpable purpura and other vascular lesions Prognosis Glucocorticoids can lead to remission at 6 months in > 90% of patients