81 Monoclonal Gammopathy of Undetermined Significance (MGUS)

Michelle To and Valentin Villatoro


MGUS is characterized has having an increase in serum M protein, clonal plasma cells, a lack of CRAB symptoms (hyperCalcemia, Renal failure, Anemia, or lytic Bone lesions), and no diagnosis of any other B cell lymphoproliferative disorder.1,2


Patients are asymptomatic and present with no other physical abnormalities.1,3



No specific cause has been linked to the development of MGUS.1


Age Group Affected: >50 years old.1,3


Laboratory Results for MGUS:1,2



Increased Plasma cells (<10%)


Slightly increased numbers of plasma cells with minimal morphological abnormalities

Immunologic Markers:

CD19, CD38, CD138

Other Tests:

Protein electrophoresis


Flow cytometry



1. Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, et al. editors. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues Volume 2. 4th ed. International Agency for Research on Cancer (IARC); 2008.

2. Craig F. Mature lymphoid neoplasms. In: Clinical laboratory hematology. 3rd ed. New Jersey: Pearson; 2015. p. 535-56.

3. Rajkumar SV. Multiple myeloma: 2016 update on diagnosis, risk-stratification, and management. Am J Hematol [Internet]. 2016 Jul [cited 2018 Jun 27];91(7):719–34. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5291298/


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A Laboratory Guide to Clinical Hematology by Michelle To and Valentin Villatoro is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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