An 80 year old asymptomatic woman was detected to have a monoclonal spike on serum electrophoresis (IgG levels 1.5 g/dl). Bone marrow revealed plasma cells of 8%. The most likely diagnosis is:

Answer is C (Monoclonal gammopathy of unknown significance) 'Patients with monoclonal gammopathy of unceain significance have < 10% bone marrow plasma cells, and < 3g / dl of M component', Presence of 8% bone marrow plasma cells and 1.5 gm/dl of M component in the form of IgG in this patient thus lead us to the above diagnosis. Plasma cell dyscrasia : Monoclonal gammopathies : Paraproteinemias : dysproteinemias These are monoclonal neoplasms characterized by expansion of a single clone of immunoglobulin secreting cells (plasma cells) and result in increase in serum levels of a single homogenous 'immunoglobulin' or - its fragments (light chains or heavy chains). The most impoant differential diagnosis in patients with multiple myeloma involves their distinction from individuals with MGUS or Benign monoclonal gammopathy: Parameters Multiple myeloma Monoclonal gammopathy of undetermined significance I. Age Q > 50 years > 50 years 2. Incidence Q Less common More common 3. Plasma cells Q (%age) > 10% < 10% 4. M component Q (concentration : g/dl) > 3g/dl < 3g/di 5. Benze Jones Q proteins Present No urinary Bence Jones proteins 6. Clinical features Q Lytic bones lesions Hypercalcemia Renal failure Anemia No Lytic bony lesionsQ No hypercalcemiaQ No renal failuree No anemiae 7. Labelling index Q (Thymidine) > 1% < 1% 8. Plasma cell - acid phosphatase - glucoronidase High High Low Low 9. Treatment Required No therapy required Woldenstorm's macroglobulinemia: is also a monoclonal gammopathy and is characterized by neoplasm of lymphoplasma cytoid cells that secrete IgM M component is only IgM and not IgG.