Bleeding Propensity in Waldenström Macroglobulinemia: Potential Causes and Evaluation.

Waldenström macroglobulinemia (WM) is a rare, incurable, low-grade, B cell lymphoma. Symptomatic disease commonly results from marrow or organ infiltration and hyperviscosity secondary to immunoglobulin M paraprotein, manifesting as anemia, bleeding and neurological symptoms among others. The causes of the bleeding phenotype in WM are complex and involve several intersecting mechanisms. Evidence of defects in platelet function is lacking in the literature, but factors impacting platelet function and coagulation pathways such as acquired von Willebrand factor syndrome, hyperviscosity, abnormal hematopoiesis, cryoglobulinemia and amyloidosis may contribute to bleeding. Understanding the pathophysiological mechanisms behind bleeding is important, as common WM therapies, including chemo-immunotherapy and Bruton's tyrosine kinase inhibitors, carry attendant bleeding risks. Furthermore, due to the relatively indolent nature of this lymphoma, most patients diagnosed with WM are often older and have one or more comorbidities, requiring treatment with anticoagulant or antiplatelet drugs. It is thus important to understand the origin of the WM bleeding phenotype, to better stratify patients according to their bleeding risk, and enhance confidence in clinical decisions regarding treatment management. In this review, we detail the evidence for various contributing factors to the bleeding phenotype in WM and focus on current and emerging diagnostic tools that will aid evaluation and management of bleeding in these patients.

A practical guide to laboratory investigations at diagnosis and follow up in Waldenström macroglobulinaemia: recommendations from the Medical and Scientific Advisory Group, Myeloma Australia, the Pathology Sub-committee of the Lymphoma and Related Diseases Registry and the Australasian Association of Clinical Biochemists Monoclonal Gammopathy Working Group.

Waldenström macroglobulinaemia (WM) is an indolent non-Hodgkin lymphoma which usually presents with symptoms related to infiltration of bone marrow or other tissues like lymph nodes, liver or spleen and has certain unusual clinical manifestations, e.g., renal and central nervous system (CNS) involvement. It also has an array of laboratory features including hypersecretion of IgM, cryoglobulinaemia, increased plasma viscosity and identification of mutated MYD88L265P in more than 90% of cases. In this review, we aim to provide a guide to the laboratory investigations recommended for WM at initial diagnosis and at follow-up. A discussion on the nuances of diagnosis and differential diagnoses is followed by bone marrow (BM) assessment, measurement of paraprotein and other ancillary investigations. Recommendations are provided on laboratory work-up at diagnosis, in the asymptomatic follow-up phase, and during and post-treatment. Finally, we briefly discuss the implications of laboratory diagnosis in regard to recruitment and monitoring on clinical trials.