A CASE OF SUDDEN DETERIORATION DUE TO ANEURYSM RUPTURE DIAGNOSED AS CHOLESTEROL EMBOLIZATION BY AUTOPSY

Cholesterol crystal embolism (CCE) is a systemic disease caused by atherosclerotic plaque rupture in large arteries, leading to distal embolization of cholesterol crystals and resultant vasculitis. While iatrogenic factors such as vascular manipulation and anticoagulation therapy are common triggers, spontaneous onset without apparent cause can occur in patients with advanced atherosclerosis. CCE can present with a wide spectrum of symptoms depending on the affected organs, including acute kidney injury, livedo reticularis, and digital necrosis.

An 80-year-old male with diabetic kidney disease had been receiving outpatient care. One year ago, he developed acute pulmonary edema and required temporary hemodialysis, from which he was successfully weaned. He was transferred to another hospital for impending rupture of a left common iliac artery aneurysm. He underwent coronary artery bypass grafting and had a left forearm arteriovenous fistula created. However, he declined surgical repair of the aneurysm and was referred back to our hospital. One week after re-referral, he was admitted with sepsis. Despite conservative treatment with antibiotics, he died of rupture of the left common iliac artery aneurysm which was confirmed by postmortem imaging. Besides, autopsy findings showed widespread cholesterol emboli in multiple organs despite no eosinophilia observed.

Multiple cholesterol crystal emboli were detected in the kidneys, lungs, and other organs including the heart. There was no evidence of atherosclerosis in the pulmonary or bronchial arteries. Cholesterol crystals were presumed to have passed through the arteriovenous fistula to the right-sided circulation, causing pulmonary involvement. Histologically, needle-shaped clefts were observed within small arteries, accompanied by inflammatory cell infiltration and vascular occlusion. This finding supports the diagnosis of CCE as a cause of multiorgan dysfunction. The coexistence of hemorrhagic shock from aneurysm rupture and CCE-related microvascular injury likely resulted in fatal circulatory collapse.

We report a hemodialysis patient without eosinophilia who suddenly died of aneurysm rupture and was diagnosed with CCE on autopsy. CCE is detected in 0.2–3.4% of autopsy cases. The prognosis is poor with a 1-year mortality rate of 60–90%. Hemodialysis patients are at particularly high risk due to severe atherosclerosis and frequent vascular procedures. In this case, a “shaggy aorta” on prior contrast CT suggested the presence of unstable atheromatous plaques, conferring a high risk for spontaneous cholesterol embolization. Cholesterol crystals in the lungs probably via the arteriovenous fistula is rare but has been reported in dialysis patients. This case highlights a distinctive pathophysiological mechanism in which emboli can bypass the systemic capillary bed through dialysis access, resulting in pulmonary CCE. Clinicians should be aware that in patients with extensive atherosclerosis, CCE can occur even without recent invasive procedures or anticoagulant use. Approximately 20–30% of CCE cases lack eosinophilia, with a tendency to be more common in the elderly and patients with end-stage kidney disease, whose immune responses are sluggish.