Multiple myeloma (MM) consists of a neoplastic proliferation of plasma cells that accumulate in the bone marrow and produce a monoclonal immunoglobulin (IgG, IgM, IgA, or rarely, IgE or IgD) or light chain protein (kappa or lambda). MM accounts for 1% of all cancers and ~10% of all hematologic malignancies. It is twice more common in persons of African descent than in Caucasians, with a slight male predominance. Median survival is 5 to 7 years.

Multiple myeloma is asymptomatic initially. In such individuals, it is usually identified incidentally, e.g., via laboratory studies showing hypercalcemia, anemia, or proteinuria.

Features of hyperviscosity syndrome range from mild headache, dizziness or dyspnea, to severe manifestations such as altered mentation, transient ischemic attacks, retinal hemorrhages, and deep venous thrombosis. Hyperviscosity syndrome occurs due to high concentrations of serum monoclonal proteins.