Cholesterol embolization syndrome (CES) occurs when cholesterol crystals from ulcerated atherosclerotic plaques in the aorta embolize to small arteries and arterioles distally. Unlike thromboembolism (which occludes large vessels), cholesterol crystals lodge in 100-200 μm arterioles, triggering an inflammatory foreign body reaction with giant cells, intimal fibrosis, and progressive luminal narrowing. This process is often triggered by vascular procedures (catheterization, aortic surgery), anticoagulation therapy (dissolution of protective thrombus overlying the ulcerated plaque), or fibrinolytic therapy. The classic triad includes livedo reticularis, acute kidney injury, and eosinophilia. Cholesterol clefts are seen on biopsy as biconvex, needle-shaped spaces (the cholesterol dissolves during tissue processing, leaving 'clefts'). The condition is progressive and often fatal (mortality 30-80%) because ongoing embolization causes multi-organ damage.