TTP-like Syndrome: Novel Concept as Endotheliopathy-associated Vascular Microthrombotic Diseasae

Thrombotic thrombocytopenic purpura (TTP) is characterized by microangiopathic hemolytic anemia and thrombocytopenia associated with brain and kidney dysfunction. It occurs due to ADAMTS13 deficiency. Critically ill patients who have additional organ dysfunction syndromes and similar hematologic changes also experience TTP-like syndrome. TTP and TTP-like syndrome are included in vascular microthrombotic disease (VMTD) because their underlying pathology is the same: disseminated intravascular microthrombosis (DIT). Platelet-unusually large von Willebrand factor multimer (ULVWF) complexes make up microthrombi. TTP results from the buildup of circulating ULVWF brought on by ADAMTS13 deficiency. Platelet activation and excessive endothelial exocytosis of ULVWF from endothelial cells are encouraged by the activation of the microthrombotic pathway (ECs). Uncleaved and overexpressed ULVWF binds to ECs as long, elongated strings in order to draw in activated platelets and assemble "microthrombi." Thus, this author’s contention is TTP and TTP-like syndrome are two distinctly different disorders with dissimilar underlying pathology and pathogenesis.