<prompt> An 80 year old asymptomatic woman was detected to have a monoclonal spike on serum electrophoresis IgG levels 1.5 gdl. Bone marrow revealed plasma cells of 8. The most likely diagnosis is:Multiple myelomaIndolent myelomaMonoclonal gammopathy of unknown significanceWaldenstorms macroglobulinemia  <response>: 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 gmdl 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 : gdl 3gdl 3gdi 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 Woldenstorms 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. 