Waldenstrom Macroglobulinemia

Overview
  • Waldenstrom Macroglobulinemia is a neoplasm of IgM secreting plasma cell which presents clinically with a hyperviscosity syndrome along with lymphadenopathy and splenomegaly. The disease tends to occur in the elderly and is fairly indolent in course. Because Waldenstrom and Multiple Myeloma are both antibody-secreting plasma cell neoplasms, comparing and contrasting these two diseases is helpful.
Pathogenesis and Clinical Consequences
  • The major clinical feature of Waldenstrom Macroglobulinemia is a hyperviscosity syndrome caused by the high concentration of serum IgM. Ultimately, the mechanisms by which IgM increases blood viscosity are likely complex and multifactorial but IgM binding of erythrocytes, leading to their aggregation, may be contributory. In some patients, binding of IgM to erythrocytes may be more severe, resulting in cryoglobulinemia and in some cases a Cold Autoimmune Hemolytic Anemia (Cold AIHA).
  • Waldenstrom cells infiltrate the bone marrow and lymphatic organs from where they secrete large amounts of monoclonal IgM. Unlike Myeloma, Waldenstrom cells do not appear to secrete bone resorptive cytokines and thus bone lesions and hypercalcemia are not features of this disease. Additionally, because IgM does not filter through the glomerulus and Waldenstrom cells rarely secrete excess light chain, renal failure is also rarely observed. In contrast to myeloma, Waldenstrom cells can infiltrate into lymphoid organs, yielding lymphadenopathy and splenomegaly in some patients.