Monoclonal gammopathy of undetermined significance

Asymptomatic premalignant disorder associated with relatively low risk (on average 0.5%-1.0% per year) of progression to multiple myeloma or related plasma cell proliferative malignancies.

No etiologic risk factors have been defined. Male gender, older age, family history of monoclonal gammopathy of undetermined significance, black ancestry, and exposure to radiation or pesticide are associated with a higher prevalence.

There is no indication for specific treatment. Clinical- and laboratory-based follow-up is recommended.

Monoclonal gammopathy of undetermined significance (MGUS) is an asymptomatic disorder associated with an increased risk of developing multiple myeloma and related plasma cell proliferative malignancies. The following criteria must be met for diagnosis: 1) presence of a monoclonal (M) protein in the serum (at a concentration <3 g/dL) or in urine (<500 mg per 24 hours); 2) <10% plasma cells in the bone marrow (a bone marrow exam is only required if M protein is >1.5 g/dL, or for non-IgG MGUS, or if the free light chain ratio is abnormal); and 3) an absence of lytic bone lesions, anemia, hypercalcemia, renal insufficiency, or amyloidosis related to the plasma cell proliferative process. [1] Rajkumar SV, Dimopoulos MA, Palumbo A, et al. International Myeloma Working Group updated criteria for the diagnosis of multiple myeloma. Lancet Oncol. 2014;15:e538-e548. http://www.ncbi.nlm.nih.gov/pubmed/25439696?tool=bestpractice.com [Figure caption and citation for the preceding image starts]: Hematoxylin-eosin section of bone marrow biopsy showing mild increase in plasma cells From the collection of Ola Landgren, MD, PhD [Citation ends]. [Figure caption and citation for the preceding image starts]: CD138 immunohistochemical staining highlighting small clusters of plasma cells From the collection of Ola Landgren, MD, PhD [Citation ends].