**3.2 von Willebrand factor deficiency (von Willebrand syndrome)**

Few case reports of concurrent acquired von Willebrand syndrome (AWS), an acquired vWF deficiency, with the presence of aPL were described [44–48]. Interestingly, other disorders with well-defined relation to AWS (myeloproliferative neoplasm, aortic valve stenosis, connective tissue diseases such as SLE) were identified in most cases. Therefore, aPL are not regarded as a usual cause of AWS, but rather as a coincidental finding in underlying immune disorders. Some researchers speculated that aPL might modify and counterbalance the bleeding phenotype typical for AWS [44, 48]. Thrombotic event after normalization of vWF was reported [44]. Immunosuppression, the standard treatment of AWS, combined with antithrombotic prevention, was given in reported cases with good clinical outcomes.
