The patient with antiphospholipid syndrome with or without lupus

Abstract

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by recurrent arterial or venous thrombosis and/or pregnancy loss, accompanied by laboratory evidence of antiphospholipid antibodies (aPL), namely anticardiolipin antibodies (aCL), lupus anticoagulant (LA), and antibodies directed against beta-2 glycoprotein 1 (β‎‎‎2GP1). APS may occur as a ‘primary’ form, ‘antiphospholipid syndrome,’ without any known systemic disease or may occur in the context of systemic lupus erythematosus (SLE), ‘SLE-related APS’. APS may affect any organ system and displays a broad spectrum of thrombotic manifestations, ranging from isolated lower extremity deep vein thrombosis to the ‘thrombotic storm’ observed in catastrophic antiphospholipid syndrome. Less frequently, patients present with non-thrombotic manifestations (e.g. thrombocytopaenia, livedo reticularis, pulmonary hypertension, valvular heart disease, chorea, and recurrent fetal loss).The kidney is a major target organ in both primary and SLE-related APS. Renal involvement is typically caused by thrombosis occurring at any location within the renal vasculature, leading to diverse effects, depending on the size, type, and site of vessel involved. The renal manifestations of APS include renal artery stenosis and/or renovascular hypertension, renal infarction, APS nephropathy (APSN), renal vein thrombosis, allograft vasculopathy and vascular thrombosis, and thrombosis of dialysis access.Typical vascular lesions of APSN may be acute, the so-called thrombotic microangiopathy, and/or chronic, such as arteriosclerosis, fibrous intimal hyperplasia, tubular thyroidization, and focal cortical atrophy. The spectrum of renal lesions includes non-thrombotic conditions, such as glomerulonephritis. Furthermore, renal manifestations of APS may coexist with other pathologies, especially proliferative lupus nephritis.Early diagnosis of APS requires a high degree of clinical suspicion. The diagnosis requires one clinical (vascular thrombosis or pregnancy morbidity) and at least one laboratory (LA, aCL, and/or anti-β‎‎‎2GP1) criterion, positive on repeated testing.The aetiology of APS is not known. Although aPL are diagnostic of, and pathogenic in, APS, a ‘second hit’ (usually an inflammatory event) may trigger thrombosis in APS. The pathogenesis of the thrombotic tendency in APS remains to be elucidated, but may involve a combination of autoantibody-mediated dysregulation of coagulation, platelet activation, and endothelial injury.Treatment of APS remains centred on anticoagulation; however, it has also included the use of corticosteroids and other immunosuppressive therapy. The prognosis of patients with primary APS is variable and unpredictable. The presence of APS increases morbidity (renal and cerebral) and mortality of SLE patients.