Waldenstroms Macroglobulinaemia (WM) is associated to lymphoplasmacytic lymphoma and is an uncommon B-cell lymphoproliferative disorder. There is variable plasmacytoid differentiation and it involves bone marrow infiltration and production of a monoclonal immunoglobulin IgM. It is diagnosed when there is evidence of bone marrow infiltration by lymphoplasmacytoid lymphoma. It always involves the bone marrow and in one third of patients also involves lymph nodes, spleen and liver.
It generally occurs in older adults and accounts for less than 5% of NHLs. Family history appears to be a risk factor but otherwise WM is a sporadic disease. Patients treated with single alkylating agents show a response rate of 70% and a 12% complete response. In general patients have a good overall response rate of 75% but complete response rates are low. Ibrutinib has been approved for WM since 2015 and has shown greater response rates and disease-free progression. In the absence of symptoms, physicians will generally just monitor before treating.