Lymphoma and plasma cell neoplasms
Plasma cell neoplasms
Monoclonal gammopathy of undetermined significance (MGUS)

Author: Nikhil Sangle, M.D. (see Authors page)

Revised: 3 April 2017, last major update March 2011

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PubMed Search: monoclonal gammopathy of undetermined significance (MGUS) lymphoma

Cite this page: Monoclonal gammopathy of undetermined significance (MGUS). PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/lymphomaMGUS.html. Accessed December 15th, 2017.
Definition / general
  • Monoclonal immunoglobulin in serum or urine without clinical features of multiple myeloma or macroglobulinemia
  • By definition, no evidence of other B cell lymphoproliferative disorder
Clinical features
  • More common than multiple myeloma (1 million vs. 13,000 cases / year in U.S.)
  • Higher prevalence in African Americans
  • Incidence increases with age (mean age 64 years): 1% of healthy people age 50+ years vs. 3% at 70+ years
  • Paraprotein is usually discovered unexpectedly: 70% IgG, 15% IgM, 12% IgA, 3% biclonal; monoclonal light chain in urine in 1/3
  • Serum immunoglobulin level less than 3 g/dl
  • No myeloma related organ or tissue impairment (no CRAB features related to myeloma: hypercalcemia, renal insufficiency, anemia, bone lesions)
  • Follow with serial measurements of monoclonal protein but usually no specific treatment
  • Risk of progression to overt myeloma is 1% per year; can evolve to myeloma, amyloidosis, Waldenström macroglobulinemia or other lymphoproliferative disorder
  • In one study, 26% progressed to overt malignant plasma cell disorder over median of 10 years
Microscopic (histologic) description