An 80 year old asymptomatic woman on a routine examination was detected to have a monoclonal spike on serum electrophoresis (IgG levels 1.5 g/dl). Bone marrow revealed plasma cells of 8%. Which of the following represents the most likely diagnosis?

Patient is showing features of monoclonal gammopathy of unknown significance. It refers to a clinical condition, defined by the presence of monoclonal immunoglobulin production without evidence of myeloma, waldenstorms macroglobulinemia or other lymphoproliferative disorder. It is an incidental finding detected by elevated total protein concentration. Serum protein electrophoresis shows a monoclonal spike. In MGUS, IgG is seen in 75% cases, IgM in 15% and IgA in 10%. Plasma cells in the bone marrow and smear appear mature ( Ref: Harrisons Principles of Internal Medicine, 18th Edition, Chapter 111 ; Hematopathology: Morphology, Immunophenotype, Cytogenetics and Molecular By Faramarz Naeim, Page 386 ; Cancer and The Kidney: The Frontier of Nephrology and Oncology By Eric P. Cohen, 2nd Edition, Page 102