VWF and cancer: TMA may result from 4 types of lesions: von Willebrand factor (VWF)-platelet thrombi with no or minimal microangiopathy; fibrin-platelet thrombi, as exemplified by disseminated intravascular coagulopathy (DIC); inflammatory or proliferative microangiopathy accompanied with variable fibrin thrombi; or intravascular clusters of cancer cells [19].