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Lymphoma - B cell neoplasms

Plasma cell neoplasms

Monoclonal gammopathy of undetermined significance (MGUS)

Reviewer: Nikhil Sangle, M.D., University of Utah and ARUP Laboratories (see Reviewers page)
Revised: 13 March 2011, last major update March 2011
Copyright: (c) 2001-2011, PathologyOutlines.com, Inc.


● 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 US)
● 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 3g/dl
● No myeloma-related organ or tissue impairement (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, Waldenstrom’s macroglobulinemia or other lymphoproliferative disorder
● In one study, 26% progressed to overt malignant plasma cell disorder over median of 10 years

Micro description

● <10% clonal plasma cells in bone marrow
● Plasma cells lack nucleoli (Am J Clin Pathol 2001;115:127)

End of Lymphoma - B cell neoplasms > Plasma cell neoplasms > Monoclonal gammopathy of undetermined significance (MGUS)

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