Nayef M. Kazzaz, W. Joseph McCune, Jason S. Knight

Catastrophic antiphospholipid syndrome (CAPS) is a severe manifestation of antiphospholipid syndrome (APS). Although affecting only 1% of patients with APS, the condition is frequently fatal if not recognized and treated early. Here, we will review the current approach to diagnosis and treatment of CAPS. Data from the international 'CAPS registry', spearheaded by the European Forum on Antiphospholipid Antibodies, have improved our understanding of at-risk patients, typical clinical features, and precipitating diagnoses. Current guidelines also continue to support the role of anticoagulants and glucocorticoids as foundation therapy in all patients. Finally, new basic science and case series suggest that novel therapies, such as rituximab and eculizumab, warrant further study. Attention to associated diagnoses, such as infection and systemic lupus erythematosus (SLE), is critical at the time of diagnosis. All patients should be treated with anticoagulants, corticosteroids, and possibly plasma exchange. In patients with SLE, cyclophosphamide should also be considered. In refractory or relapsing cases, new therapies, such as rituximab and possibly eculizumab, may be options, but need further study.