INTRODUCTION: ANCA-associated vasculitides (AAV) refer to a group of disorders causing inflammation of small vessels which include granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA, Churg-Strauss). Here I present a case of MPA vasculitis in a patient with alpha-1-antitrypsin (AAT) deficiency, and describe a proposed causal link between these two rare disease processes. CASE REPORT: • 43-year-old man with history of newly-diagnosed AAT deficiency liver disease. • Chief complaint of subacute shortness of breath associated with hemoptysis and fever for 5 months. • Symptoms had been progressively worsening despite multiple courses of antibiotics and inhalers. • Pulmon...