Sudden unexpected death due to coronary thrombosis associated with isolated necrotizing vasculitis in the coronary arteries of a young adult.

Coronary arteritis is an uncommon cause of sudden death in non-atherosclerotic coronary diseases, and is mostly associated with systemic vasculitis or systemic autoimmune diseases; therefore, sudden death due to isolated coronary arteritis rarely occurs. The case described in this report is that of a 34-year-old man with no significant personal medical history who died suddenly after presenting with nausea. Postmortem examination revealed a significant infiltration of lymphocytes predominantly on the adventitia and periadventitial tissues of the coronary arteries in the epicardium. The lymphocytic infiltrate partially extended to the thickened intima with fibrosis, destructing the media and internal elastic lamina, and the lumen was occluded by a thrombus in the left main stem and left anterior descending branch. The arterial walls exhibited focal fibrinoid necrosis with regression in the intima and fibrous scars with angiogenesis in the media and adventitia. Focal myocardial infarction was detected in the left ventricle as a fibrotic change of the myocardium. No findings associated with vasculitis were discerned in the aorta, other peripheral arteries, or major organs. Laboratory tests of postmortem blood samples returned negative results for antinuclear antibodies, cryoglobulin, immunoglobulin G4, and cytoplasmic anti-neutrophil cytoplasmic antibodies for myeloperoxidase and proteinase 3. These autopsy findings suggest that the sudden death was caused by isolated necrotizing vasculitis that is assumed to be polyarteritis nodosa localized at the coronary arteries. However, pathological characteristics may not be exactly the same between isolated necrotizing vasculitis in the coronary arteries and polyarteritis nodosa.