An Unusual Presentation of IgM Myeloma.

Immunoglobulin M (IgM) paraproteinemia is usually associated with either lymphoplasmacytic lymphoma (LPL) or Waldenström's macroglobulinemia (WM). Manifestations due to IgM paraprotein include hyperviscosity, acquired coagulopathy, cryoglobulinemia, vasculitis, and cold antibody-mediated autoimmune hemolytic anemia. These manifestations are seen in variable percentage of patients with LPL/WM. IgM myeloma constitutes only 0.5-1% of all myeloma cases. We describe a middle-aged female who presented with 5C's: cryoglobulinemia, coagulopathy (acquired von Willebrand disease), cold autoimmune hemolytic anemia, clot (thrombosis due to vasculitis), and cloudy vision (hyperviscosity syndrome) attributable to IgM paraprotein, but was diagnosed later with IgM myeloma. IgM is an important differential diagnosis of WM. The current case highlights such diagnostic challenges and their therapeutic considerations.