Prevalence and pathology of vascular occlusive disease in the antiphospholipid syndromes

Vascular occlusive disease occurs not infrequently in patients with antiphospholipid syndromes (APS) and, in some, may be associated with catastrophic complications. Recurrent, large- and small-vessel, arterial and/or venous thrombosis, and not vasculitis, is the only known and proven pathologic basis of virtually all clinical manifestations of APS in systemic, pulmonary, and/or cerebral circulations. Whether the vasculopathy of APS is thrombosis or vasculitis is of more than mere academic interest; the distinction is important not only for unravelling the pathogenesis of vascular injuries in APS but also for making the correct choice of drug treatment. A diagnosis of vasculitis would call for treatment with immunosuppressive and cytotoxic agents replete with undesirable and serious side effects. Furthermore, these powerful, but potentially dangerous, drugs are quite ineffectual in resolving or preventing the thrombosis associated with APS, which has been demonstrated clinically to respond to the lowly and inexpensive aspirin.