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Monoclonal gammopathy of undetermined significance

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Not to be confused withMonoclonal gammopathy.
Monoclonal gammopathy of undetermined significance
Other namesBenign monoclonal gammopathy, monoclonal gammopathy of unknown significance, monoclonal gammopathy of renal significance,[1]unknownoruncertainmay be substituted forundetermined
Schematic representation of a normalprotein electrophoresisgel. A small spike would be present in the gamma (γ) band in MGUS

Monoclonal gammopathy of undetermined significance(MGUS) is aplasma cell dyscrasiain whichplasma cellsor other types of antibody-producing cells secrete amyeloma protein,i.e. an abnormalantibody,into theblood;this abnormal protein is usually found during standard laboratorybloodorurine tests.MGUS resemblesmultiple myelomaand similar diseases, but the levels of antibodies are lower,[2]the number ofplasma cells(white blood cellsthat secrete antibodies) in thebone marrowis lower, and it rarely has symptoms or major problems. However, since MGUS can lead to multiple myeloma, which develops at the rate of about 1.5% a year, or other symptomatic conditions, yearly monitoring is recommended.

The progression from MGUS to multiple myeloma usually involves several steps. In rare cases, it may also be related with a slowly progressive symmetric distal sensorimotorneuropathy.[3]

Signs and symptoms

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People with monoclonal gammopathy generally do not experience signs or symptoms.[1]Some people may experience a rash or nerve problems, such as numbness or tingling.[1]MGUS is usually detected by chance when the patient has a blood test for another condition or as part of standard screening.[1]

Pathophysiology

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Pathologically, the lesion in MGUS is in fact very similar to that in multiple myeloma. There is a predominance ofclonalplasma cellsin thebone marrowwith an abnormalimmunophenotype(CD38+CD56+CD19−) mixed in with cells of a normal phenotype (CD38+ CD56− CD19+);[4][5]in MGUS, on average more than 3% of the clonal plasma cells have the normal phenotype, whereas in multiple myeloma, less than 3% of the cells have the normal phenotype.[6]

Diagnosis

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MGUS is a common, age-related medical condition characterized by an accumulation of bone marrow plasma cells derived from a single abnormal clone. Patients may be diagnosed with MGUS if they fulfill the following four criteria:[7]

  1. A monoclonal paraprotein band less than 30 g/L (< 3g/dL);
  2. Plasma cellsless than 10% onbone marrow examination;
  3. No evidence of bone lesions,anemia,hypercalcemia,orchronic kidney diseaserelated to the paraprotein, and
  4. No evidence of another B-cell proliferative disorder.

Differential diagnosis

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Several other illnesses can present with amonoclonal gammopathy,and the monoclonal protein may be the first discovery before a formal diagnosis is made:

Management

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MGUS occurs in over 3 percent of the White population over the age of 50, and is typically detected as an incidental finding when patients undergo a protein electrophoresis as part of an evaluation for a wide variety of clinical symptoms and disorders (e.g., peripheral neuropathy, vasculitis, hemolytic anemia, skin rashes, hypercalcemia, or elevated erythrocyte sedimentation rate). Although patients with MGUS have sometimes been reported to haveperipheral neuropathy,a debilitating condition which causes bizarre sensory problems to painful sensory problems,[13]no treatment is indicated.[citation needed]

Theprotein electrophoresistest should be repeated annually, and if there is any concern for a rise in the level of monoclonal protein, then prompt referral to ahematologistis required. The hematologist, when first evaluating a case of MGUS, will usually perform askeletal survey(X-rays of the proximal skeleton), check the blood forhypercalcemiaand deterioration inrenal function,check the urine forBence Jones proteinand perform abone marrow biopsy.If none of these tests are abnormal, a patient with MGUS is followed up once every 6 months to a year with a blood test (serum protein electrophoresis).[citation needed]

Prognosis

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At the Mayo Clinic, MGUS transformed into multiple myeloma or similarlymphoproliferative disordersat the rate of about 1–2% a year, or 17%, 34%, and 39% at 10, 20, and 25 years, respectively, of follow-up—among surviving patients. However, because they were elderly, most patients with MGUS died of something else and did not go on to develop multiple myeloma. When this was taken into account, only 11.2% developed lymphoproliferative disorders.[14]

Kyle et al. studied the prevalence of myeloma in the population as a whole (not clinic patients) inOlmsted County, Minnesota.They found that the prevalence of MGUS was 3.2% in people above 50, with a slight male predominance (4.0% vs. 2.7%). Prevalence increased with age: of people over 70 up to 5.3% had MGUS, while in the over-85 age group the prevalence was 7.5%. In the majority of cases (63.5%), the paraprotein level was <1 g/dL, while only a very small group had levels over 2 g/dL.[15]

A study of monoclonal protein levels conducted inGhanashowed a prevalence of MGUS of approximately 5.9% in African men over the age of 50.[16]

In 2009, prospective data demonstrated that all or almost all cases of multiple myeloma are preceded by MGUS.[17]

In addition to multiple myeloma, MGUS may also progress toWaldenström's macroglobulinemiaor primaryamyloidosis.[12]

See also

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References

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  1. ^abcdKaushansky, Kenneth (2016).Williams Hematology.United States: McGraw Hill. pp. 1723–1727.ISBN9780071833011.
  2. ^Agarwal, A;Ghobrial, IM(1 March 2013)."Monoclonal gammopathy of undetermined significance and smoldering multiple myeloma: a review of the current understanding of epidemiology, biology, risk stratification, and management of myeloma precursor disease".Clinical Cancer Research.19(5): 985–94.doi:10.1158/1078-0432.CCR-12-2922.PMC3593941.PMID23224402.
  3. ^Kahn S. N.; Riches P. G.; Kohn J. (1980)."Paraproteinaemia in neurological disease: incidence, associations, and classification of monoclonal immunoglobulins".Journal of Clinical Pathology.33(7): 617–621.doi:10.1136/jcp.33.7.617.PMC1146171.PMID6253529.
  4. ^Zhan F, Hardin J, Kordsmeier B, Bumm K, Zheng M, Tian E, Sanderson R, Yang Y, Wilson C, Zangari M, Anaissie E, Morris C, Muwalla F, van Rhee F, Fassas A, Crowley J, Tricot G, Barlogie B, Shaughnessy J (2002)."Global gene expression profiling of multiple myeloma, monoclonal gammopathy of undetermined significance, and normal bone marrow plasma cells".Blood.99(5): 1745–1757.doi:10.1182/blood.V99.5.1745.PMID11861292.
  5. ^Magrangeas F, Nasser V, Avet-Loiseau H, Loriod B, Decaux O, Granjeaud S, Bertucci F, Birnbaum D, Nguyen C, Harousseau J, Bataille R, Houlgatte R, Minvielle S (2003)."Gene expression profiling of multiple myeloma reveals molecular portraits in relation to the pathogenesis of the disease".Blood.101(12): 4998–5006.doi:10.1182/blood-2002-11-3385.PMID12623842.
  6. ^Ocqueteau M, Orfao A, Almeida J, Bladé J, González M, García-Sanz R, López-Berges C, Moro M, Hernández J, Escribano L, Caballero D, Rozman M, San Miguel J (1998)."Immunophenotypic characterization of plasma cells from monoclonal gammopathy of undetermined significance patients. Implications for the differential diagnosis between MGUS and multiple myeloma".Am J Pathol.152(6): 1655–65.PMC1858455.PMID9626070.
  7. ^International Myeloma Working Group (2003)."Criteria for the classification of monoclonal gammopathies, multiple myeloma and related disorders: a report of the International Myeloma Working Group".Br J Haematol.121(5): 749–757.doi:10.1046/j.1365-2141.2003.04355.x.PMID12780789.S2CID3195084.
  8. ^Murakami H, Irisawa H, Saitoh T, Matsushima T, Tamura J, Sawamura M, Karasawa M, Hosomura Y, Kojima M (1997)."Immunological abnormalities in splenic marginal zone cell lymphoma".Am. J. Hematol.56(3): 173–178.doi:10.1002/(SICI)1096-8652(199711)56:3<173::AID-AJH7>3.0.CO;2-V.PMID9371530.
  9. ^Larking-Pettigrew M, Ranich T, Kelly R (1999). "Rapid onset monoclonal gammopathy in cutaneous lupus erythematosus: interference with complement C3 and C4 measurement".Immunol. Invest.28(4): 269–276.doi:10.3109/08820139909060861.PMID10454004.
  10. ^Czaplinski A, Steck A (2004). "Immune mediated neuropathies--an update on therapeutic strategies".J. Neurol.251(2): 127–137.doi:10.1007/s00415-004-0323-5.PMID14991345.S2CID13218864.
  11. ^Sykes, David B.; Schroyens, Wilfried; O'Connell, Casey (2011)."TEMPI Syndrome – A Novel Multisystem Disease".N Engl J Med.365(5): 475–477.doi:10.1056/NEJMc1106670.PMID21812700.S2CID35990145.
  12. ^abGo, Ronald S.; Rajkumar, S. Vincent (2018-01-11)."How I manage monoclonal gammopathy of undetermined significance".Blood.131(2): 163–173.doi:10.1182/blood-2017-09-807560.ISSN0006-4971.PMC5757684.PMID29183887.
  13. ^Nobile-Orazio E.; et al. (June 1992). "Peripheral neuropathy in monoclonal gammopathy of undetermined significance: prevalence and immunopathogenetic studies".Acta Neurologica Scandinavica.85(6): 383–390.doi:10.1111/j.1600-0404.1992.tb06033.x.PMID1379409.S2CID30788715.
  14. ^Bladé J (2006). "Clinical practice. Monoclonal gammopathy of undetermined significance".N Engl J Med.355(26): 2765–2770.doi:10.1056/NEJMcp052790.PMID17192542.
  15. ^Kyle RA, Therneau TM, Rajkumar SV, Larson DR, Plevak MF, Offord JR, Dispenzieri A, Katzmann JA, Melton LJ 3rd (28 December 2006)."Prevalence of monoclonal gammopathy of undetermined significance".N Engl J Med.354(13): 1362–1369.doi:10.1056/NEJMoa054494.PMID16571879.
  16. ^Landgren O, Katzmann JA, Hsing AW, Pfeiffer RM, Kyle RA, Yeboah ED, Biritwum RB, Tettey Y, Adjei AA, Larson DR, Dispenzieri A, Melton LJ 3rd, Goldin LR, McMaster ML, Caporaso NE, Rajkumar SV (Dec 2007). "Prevalence of monoclonal gammopathy of undetermined significance among men in Ghana".Mayo Clin Proc.82(12): 1468–1473.doi:10.4065/82.12.1468.PMID18053453.
  17. ^Landgren O, Kyle RA, Pfeiffer RM, Katzmann JA, Caporaso NE, Hayes RB, Dispenzieri A, Kumar S, Clark RJ, Baris D, Hoover R, Rajkumar SV (28 May 2009)."Monoclonal gammopathy of undetermined significance (MGUS) consistently precedes multiple myeloma: a prospective study".Blood.113(22): 5412–7.doi:10.1182/blood-2008-12-194241.PMC2689042.PMID19179464.

Further reading

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