Bleeding and thrombosis in multiple myeloma and related plasma cell disorders

A variety of disease- and treatment-related factors affect the coagulation system and the risk of bleeding and thrombotic complications in patients with multiple myeloma (MM) and related plasma cell disorders (PCD). As commonly observed in other cancer settings, the malignant clone induces a cytokine environment responsible for a hypercoagulable state. The increase of blood viscosity and impairment of platelet and coagulation function due to circulating monoclonal proteins are considered key mechanisms in the hemostatic abnormalities frequently detected in patients with PCD. However, clinically significant bleeding is relatively rare and poorly correlated with these abnormalities. Management is often challenging because of the multifactorial pathogenesis and underestimation or misdiagnosis of acquired bleeding disorders, particularly acquired von Willebrand syndrome. In recent years, growing interest in thromboembolic risk has emerged after the introduction of novel and more effective antimyeloma agents (thalidomide and lenalidomide), which was associated with increased risk of venous thromboembolism, particularly when associated with dexamethasone and multiagent chemotherapy in newly diagnosed patients. The clinical impact of bleeding and thrombotic complications in patients with PCD, with emphasis on MM, will be discussed in this review, reporting the current knowledge about pathophysiologic mechanisms and implications for management.