Teaching Points:

• Multiple Myeloma
  • Plasma cell dyscrasia causing monoclonal antibody development complicated with end organ damage
  • Criteria For Diagnosis
    • M-spike (suggest overproduction of a specific antibody)
    • Bone Marrow Biopsy with >10% plasma cells
    • Evidence of end-organ damage (CRAB)
      • Hypercalcemia – 25%
      • Renal insufficiency – 50%
        • Prone to worsening renal disease as a result of diuresis and NSAID therapy
      • Anemia – 75%
      • Bone involvement – 50%
        • Patients present with bony pain worsened with movement.
  • Differential Diagnosis
    • Smoldering Multiple Myeloma
      • M-spike protein >3g/dl
      • Bone marrow biopsy with plasma cells >10%
      • No evidence of end organ damage (CRAB criteria)
    • MGUS
      • M-spike <3g/dL
      • Bone marrow biopsy with plasma cells <10%
      • No evidence of end organ damage (CRAB criteria)
  • Waldenstrom’s macroglobulinemia differs from multiple myeloma in that the monoclonal spike is due specifically to IgM.
    • IgM is a tetramer and instead manifests as hyperviscosity syndrome.
    • Patients may also have lymphadenopathy, splenomegaly, etc.