Catastrophic antiphospholipid syndrome: updated diagnostic algorithms.

The catastrophic antiphospholipid syndrome (APS) is the most severe form of APS with acute multiple organ involvement and small vessel thrombosis. During the 13th International Congress on Antiphospholipid Antibodies (aPL) a "Catastrophic APS Task Force" was developed to discuss the challenges in the diagnosis and management of catastrophic APS. The purpose of this paper is to summarize the diagnostic challenges (false-positive/negative aPL results and overlap with other thrombotic microangiopathies) and propose updated diagnostic algorithms for catastrophic APS. Important steps of the diagnostic algorithms include: a) history of APS or persistent aPL-positivity; b) three or more organ new thrombosis developing in less than a week; c) biopsy diagnosis of microthrombosis; and d) other explanations for multiple organ thromboses and/or microthrombosis.