Coronary artery aneurysms are rare complications of autosomal dominant polycystic kidney disease (ADPKD), and their pathogenesis remains poorly understood. We report an autopsy case of a 64-year-old ADPKD patient with an asymptomatic, large (4cm in diameter) saccular aneurysm arising from the left circumflex (LCX) branch of the coronary artery with only mild atherosclerotic changes. Autopsy also revealed small, focal defects of media with or without microaneurysm formation in the LCX, mesenteric and renal arteries, and a fibromuscular dysplasia-like lesion with microaneurysm in the common iliac artery. Since polycystin-1 and -2 are expressed in arterial smooth-muscle cells, these findings imply that abnormal polycystin expression in ADPKD initially causes the focal medial defects, some of which might later progress to microaneurysms and then overt aneurysms. To the best of our knowledge, this is the first description of the pathologic findings of an ADPKD-associated coronary aneurysm and its probable precursor lesions in arteries.
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