VWF and Cowden syndrome 1: The increased risk of VTE in CS is multifactorial, but most experts have linked it with increased activity of factor VIII and von Willebrand factor (vWF), along with impaired fibrinolysis as a consequence of its enhanced inhibition, as evidenced by elevated blood levels of plasminogen activator inhibitor 1, thrombin-activatable fibrinolysis inhibitor, and α2-antiplasmin (4).