Acquired von Willebrand syndrome secondary to Waldenström’s macroglobulinemia

Acquired von Willebrand (vW) syndrome in Waldenström’s macroglobulinemia (WM) should be differentially diagnosed from hyperviscosity syndrome of WM, which exhibits a bleeding tendency. We report a rare case of acquired vW syndrome secondary to WM. A 62-year-old woman was referred to our hospital because of extensive subcutaneous hemorrhage following a light hit to the left arm. Although the platelet count was normal, APTT was prolonged to 49.4 sec. Furthermore, the serum concentration of IgM was elevated to 7,796 mg/dL, which was revealed to be IgM-κ monoclonal protein, leading to a diagnosis of WM. On ophthalmofundoscopy, mild hemorrhage, but not retinal vein dilatation, was observed. Regarding the abnormal APTT value, we measured coagulation factors in the intrinsic arm, revealing reduced activities of vW factor and factor VIII of 11 and 18%, respectively. Furthermore, the amount of vW protein was decreased to 23%. Multimer analysis of vW factor demonstrated an abnormal pattern lacking high-molecular-weight- bands. Additional diagnosis of acquired vW syndrome secondary to WM was made. The APTT cross-mixing test showed a simple but not inhibitor-related decreasing pattern of vW factor, suggesting the absorption of this factor by abnormal lymphoplasmacytic cells. The patient was treated with bendamustine, leading to reduced IgM, improvement of the APTT value, and the normal multimer pattern of vW factor.