ABSTRACT
Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare systemic disease and a potentially life‐threatening systemic necrotizing vasculitis predominantly affecting small vessels. Herein, we describe a 47-year-old man with EGPA misdiagnosed as non-ST-segment elevation myocardial infarction. He presented to the Emergency Department with indigestion and diarrhea. He had been diagnosed with asthma and chronic rhinosinusitis 3 years earlier and was taking antibiotics due to worsening sinusitis. In laboratory tests, peripheral blood eosinophils, serum creatinine, and serum troponin were elevated to 4,641 cells/μL, 13.40 ng/mL, and 1.26 ng/ mL, respectively. Electrocardiography showed ST-segment depression on the inferior wall, and echocardiography indicated an ischemic insult in the right coronary artery territory. A non-ST-segment elevation myocardial infarction as well as antibiotic-associated diarrhea, eosinophilia and acute kidney injury was initially suspected. However, fever persisted and eosinophilia worsened despite cessation of antibiotics after admission. There was no significant stenosis of the coronary arteries on coronary angiography. Meanwhile, abdominal computed tomography suggested medical renal disease, and magnetic resonance imaging showed late gadolinium enhancement at the mid wall and the subepicardial area in the left ventricle of the heart. As a workup for eosinophilia, serum anti-MPO was measured and turned out to be positive. A kidney biopsy was performed, which yielded membranous nephropathy superimposed on antineutrophil cytoplasmic antibodies-mediated crescent formation. He was diagnosed as EGPA with cardiac and renal involvement, and received systemic steroid, cyclophosphamide, and plasmapheresis. Then, peripheral eosinophil counts and renal function were normalized. He is now in clinical remission even after stopping the use of steroids and immunosuppressive agents.