Catastrophic antiphospholipid syndrome (CAPS), also called "Asherson syndrome", is a variant of the antiphospholipid syndrome (APS) that occurs in less than 1% of APS cases. The etiology of CAPS is uncertain; however, several triggering factors have been recognized. The most common of these are infectious diseases, particularly those of the respiratory tract. CAPS pathogenesis is incompletely understood, but several theories have been proposed, such as the molecular mimicry theory, which describes the production of anti-β2-glycoprotein I (GP1) antibody in response to infection. The process is complex and involves the activation of Toll-like receptor 4 (TLR-4), which triggers a cytokine storm, followed by endothelial alterations that induce a procoagulant state. Copyright © 2015 Elsevier B.V. All rights reserved.