Diagnosis:
Antiphospholipid Antibody Syndrome (APS)
• Antiphospholipid syndrome (APS) is defined as a hypercoagulable state with arterial or venous fibrin thrombus formation caused by high titers of circulating autoantibodies directed against phospholipid and phospholipid-binding protein complexes (i.e., β2 glycoprotein 1 and phospholipid complexes on platelets and endothelial cells).
• APS is classified as secondary disease if it is accompanied by other autoimmune disorders (i.e., systemic lupus erythematosus or other connective tissue diseases) and as primary disease if it manifests only with a hypercoagulable state.
• The histologic examination typically shows fibrin thrombi of different ages, sometimes organized with signs of recanalization. Conspicuous inflammation and vascular wall necrosis are lacking.
• In APS, venous thrombosis is frequently detected in deep leg veins (55%; caveat: pulmonary emboli) as well as in renal, hepatic, and retinal veins. Arterial thrombosis is typically seen in cerebrovascular (50%), coronary (25%), ocular, mesenteric, deep leg, and renal arteries (caveat: stroke, myocardial or bowel infarction, ischemia of the lower extremities with skin ulcerations).
• Clinical manifestations are variable and can mimic a systemic vasculitis (including livedo reticularis), repeated miscarriages, and cardiac valvular vegetations (Libman-Sacks endocarditis in 4% of patients). In less than 1% of cases, multiple organ sites are affected by thrombosis simultaneously with dramatic clinical consequences and a mortality rate of 50% (termed catastrophic APS).
• APS should always be included in the differential diagnosis in patients presenting with recurrent episodes of thrombosis.
Appenzeller S, Souza FH, Wagner Silva de Souza A, et al:
HELLP syndrome and its relationship with antiphospholipid syndrome and antiphospholipid antibodies. Semin Arthritis Rheum 2011;41(3):517-523.
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Rodriguez-Garcia JL, Bertolaccini ML, Cuadrado MJ, et al:
Clinical manifestations of antiphospholipid syndrome (APS) with and without antiphospholipid antibodies (the so-called ‘seronegative APS’). Ann Rheum Dis 2012;71(2):242-244.
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Antiphospholipid antibody syndrome. Arch Pathol Lab Med 2011;135(9):1092-1096.
Tripodi A, de Groot PG, Pengo V:
Antiphospholipid syndrome: laboratory detection, mechanisms of action and treatment. J Intern Med 2011;270(2):110-122.
