Waldenström's macroglobulinemia (WM) is a lymphoproliferative disorder characterized by the presence of monoclonal lymphocytes that produce monoclonal immunoglobulin M (IgM). This disease was originally described in 1944 by Jan Waldenström, who reported two patients with long-standing oronasal bleeding, mild generalized lymphadenopathy, significant anemia, elevated erythrocyte sedimentation rate, very high serum viscosity, and low levels of fibrinogen. Large amounts of a high-molecular-weight globulin were detected in the serum of these patients, and their bone marrow aspirate revealed increased numbers of lymphocytoid cells.<sup>127 Waldenström J. Incipient myelomatosis or “essential” hyperglobulinemia with fibrinogenopenia–A new syndrome? Acta Medica Scandinavica 1944 ;  117 : 216

Cliccare qui per andare alla sezione Riferimenti</sup> The abnormal serum globulin was subsequently identified as an immunoglobulin and was called immunoglobulin M. Under the diagnosis of Waldenström's macroglobulinemia are included patients with a low-grade lymphoplasmatic disorder associated with various amounts of serum monoclonal IgM. Some individuals, however, have a monoclonal IgM of undetermined significance without symptoms, without organomegaly or lymphadenopathy, and without anemia or evidence of bone marrow infiltration by the lymphoma. Such individuals do not require treatment, but some may develop overt WM.<sup>68 Kyle R.A., Garton J.P. The spectrum of IgM monoclonal gammopathy in 430 cases Mayo Clin Proc 1987 ;  62 : 719

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Waldenström's macroglobulinemia is a rare disease. Herrinton and Weiss reported an age-standardized annual incidence rate of 6.1 cases/million in white men and 2.5/million in white women. This disease is much more common in whites than in blacks.<sup>55 Herrinton L.J., Weiss N.S. Incidence of Waldenström's macroglobulinemia Blood 1993 ;  82 : 3148

Cliccare qui per andare alla sezione Riferimenti</sup> Groves et al found that the age-adjusted incidence rates for WM/1 million person-years at risk were 3.4 among men and 1.7 among women. The rates increased sharply with age, from 0.1 at ages under 45 years to 36.3 at ages over 75 years for men. The rates for WM are comparable with those for hairy cell leukemia but are considerably lower than those for multiple myeloma or chronic lymphocytic leukemia.<sup>49 Groves F.D., Travis L.B., Devesa S.S. , e al. Waldenström's macroglobulinemia: Incidence patterns in the United States, 1988–1994 Cancer 1998 ;  82 : 1078  [cross-ref]

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