Kyle RA, et al. - The incidence of Waldenstrom macroglobulinemia (WM) was investigated in a strictly defined geographic area over a 50-year period among all residents of Olmsted County with a diagnosis of WM, consisting of a monoclonal IgM protein of any size and/or 10% or more lymphoplasmacytic infiltration of the bone marrow along with anemia, constitutional symptoms, hyperviscosity, lymphadenopathy, or hepatosplenomegaly requiring therapy. Using a smoothing spline, no convincing evidence was yielded for a change in the incidence of WM. An approximately 2-fold excess mortality was reported in subjects diagnosed with WM after 2000 compared with the expected population mortality.