Cholesterol emboli - Skin
The term cutaneous cholesterol embolism signifies involvement of the skin due to cholesterol embolism. It is also referred to as cholesterol embolization syndrome, lower extremity atheromatous emboli syndrome, and purple or blue toe syndrome.
Cholesterol emboli can occur as a result of invasive coronary procedures such as major vessel surgery, angiography, angioplasty, or following anticoagulant or thrombolytic therapy. Anticoagulants and thrombolytics act by targeting the breakdown of the protective clot that stabilizes an ulcerated atheromatous lesion, thereby releasing cholesterol crystals into the bloodstream. Heparin, warfarin sodium, and streptokinase have been reported as being causative agents. Formation of cholesterol emboli may also follow cardiopulmonary resuscitation or can occur spontaneously.
Embolization occurs when cholesterol crystals splinter off from the atherosclerotic plaques and are carried in the bloodstream to distant organs. The crystals occlude arterioles by 2 mechanisms: first, the crystals physically block smaller arterioles, and second, they activate complement inducing an inflammatory response, which leads to adventitial fibrosis and obliteration of the vessel lumen. Because emboli are small and numerous, this leads to multisystem disease.
Alternatively, larger crystal plaques may break off and directly block larger arteries leading to tissue infarction and acute organ failure. As cholesterol emboli can spread to any organ, they present a wide ranging clinical picture and, hence, diagnosis is difficult. If a patient develops acute pain, skin abnormalities, impaired renal function, hypertension, ischemia in the extremities, or acute multiorgan impairment following an invasive arterial procedure, then a diagnosis of cholesterol embolism should be considered.
Risk factors for the disease are as follows:
- Extensive atherosclerosis
- Systemic hypertension
- Diabetes mellitus
- Vascular intervention such as angiography, heart catheterization, coronary artery bypass grafting, and percutaneous transluminal coronary angioplasty.
- Elevated levels of plasma C-reactive protein.
The prognosis is poor, as renal failure is progressive and patients end up requiring dialysis permanently. Ischemic changes often lead to gangrene and subsequent amputation. Death most often occurs from cardiovascular causes, and the mortality rate stands at 78%, as seen in one study. Cholesterol embolism is seen more commonly in males than in females and in whites more commonly than blacks.
Because cholesterol embolization is commonly asymptomatic, it is hard to determine the frequency with which it occurs. However, in one study, incidence of needle-shaped crystals in the lumen of affected arterioles following cardiac catheterization was found to be 10%.
I75.89 – Atheroembolism of other site
236489002 – Cholesterol embolus syndrome
The differential diagnosis includes the following:
- Polyarteritis nodosa very closely mimics cholesterol emboli syndrome in both its general manifestations and also its systemic symptoms of renal, cardiac, and cutaneous involvement. Cutaneous manifestations have a more generalized distribution in polyarteritis nodosa than in cutaneous cholesterol emboli, which is more predominant in the lower half of the body. A history of an interventional procedure should point to a diagnosis of cholesterol emboli.
- Bacterial sepsis
- Coumadin necrosis
- Heparin necrosis
- Purpura fulminans
- Ecthyma gangrenosum
- Giant cell arteritis (see polymyalgia rheumatica)
- Subacute bacterial endocarditis
- Deep venous thrombosis
- Diabetic ulcers
- Aortic dissection