目的： 分析M蛋白相关的获得性血管性血友病综合征（acquired von Willebrand syndrome，AVWS）的临床与实验室特征，提升临床识别与诊断能力。方法： 回顾性连续收集2024年10月至2026年4月期间上海交通大学医学院附属瑞金医院发现的4例M蛋白相关AVWS患者，其中3例因不明原因出血就诊，1例在住院筛查中发现止血相关实验室异常。患者经血管性血友病因子（von Willebrand factor，VWF）相关检测及遗传性血管性血友病等疾病鉴别后，进一步行血清蛋白电泳和免疫固定电泳检测M蛋白。结果： 4例患者中男性3例，女性1例；年龄38~71岁；均无长期异常出血史及家族史。4例患者中，2例结合骨髓病理及分子病理检查结果确诊为华氏巨球蛋白血症（Waldenström macroglobulinemia，WM），2例临床拟诊（未行骨髓检查）为意义未明单克隆免疫球蛋白血症（monoclonal gammopathy of undetermined significance，MGUS）。4例患者的VWF抗原（VWF antigen，VWF:Ag）、VWF活性（VWF activity，VWF:Act）、凝血因子Ⅷ活性（blood coagulation factor Ⅷ activity，FⅧ:C）均降低，其中3例患者的VWF:Act/VWF:Ag比值<0.60，其余1例为0.74。VWF多聚体定性分析显示，4例患者高分子量VWF多聚体条带较正常混合血浆均明显减少。结论： M蛋白相关AVWS以成年后起病、无家族史、伴单克隆免疫球蛋白异常、VWF活性相对抗原不成比例下降及高分子量VWF多聚体减少为主要诊断特征。对不明原因出血或VWF相关指标异常的患者，应进一步行血清蛋白电泳、免疫固定电泳及M蛋白定量，避免漏诊误诊。

Objective This study aims to analyze the clinical and laboratory characteristics of M protein-associated acquired von Willebrand syndrome (AVWS), and to improve clinical recognition and diagnostic capability. Methods Four patients with M protein-associated AVWS identified at Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, between October 2024 and April 2026 were consecutively enrolled and retrospectively reviewed. Three patients presented with unexplained bleeding, whereas one was found to have abnormal hemostatic laboratory results during inpatient scree-ning. After von Willebrand factor （VWF)-related testing and differential evaluation for inherited von Willebrand disease(VWD) and other bleeding disorders, serum protein electrophoresis and immunofixation electrophoresis were subsequently performed to detect M protein. Results Among the four patients, three were male and one was female, with ages ranging from 38 to 71 years. None had a long-standing history of abnormal bleeding or a family history of bleeding. Two patients were diagnosed with Waldenström macroglobulinemia (WM) based on bone marrow pathology and molecular pathology fin-dings, whereas two were clinically suspected of having monoclonal gammopathy of undetermined significance (MGUS) wi-thout undergoing bone marrow examination. VWF antigen (VWF:Ag), VWF activity (VWF:Act), and factor Ⅷ coagulant activity (FⅧ:C) were decreased in all four patients. The VWF:Act/VWF:Ag ratio was <0.60 in three patients, whereas the ratio was 0.74 in the remaining patient. Qualitative analysis of VWF multimers showed a marked reduction in high-molecular-weight VWF multimer bands in all four patients compared with normal pooled plasma. Conclusions The main diagnostic features of M protein-associated AVWS include adult onset, absence of a family history of abnormal bleeding, coexisting monoclonal immunoglobulin abnormalities, a disproportionate reduction in VWF activity relative to VWF antigen, and a reduction in high-molecular-weight VWF multimers. In patients with unexplained bleeding or abnormal VWF-related parameters, serum protein electrophoresis, immunofixation electrophoresis, and M protein quantification should be further performed to avoid missed diagnosis and misdiagnosis.