Monoclonal gammopathy of undetermined significance
| Monoclonal gammopathy of undetermined significance | |
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| Schematic representation of a normal protein electrophoresis gel. A small spike would be present in the gamma (γ) band in MGUS | |
| Classification and external resources | |
| ICD-10 | D47.2 |
| ICD-9-CM | 273.1 |
| ICD-O | 9765/1 |
| DiseasesDB | 1341 |
| eMedicine | med/1495 |
| MeSH | D008998 |
Monoclonal gammopathy of undetermined significance (MGUS, unknown or uncertain may be substituted for undetermined), formerly benign monoclonal gammopathy, is a condition in which a paraprotein is found in the blood during standard laboratory blood tests. It resembles multiple myeloma and similar diseases, but the levels of antibody are lower, the number of plasma cells (white blood cells that secrete antibodies) in the bone marrow is lower, it has no symptoms or major problems, although patients with MGUS have sometimes been reported to suffer from peripheral neuropathy, and no treatment is indicated. However, multiple myeloma develops at the rate of about 1.5% a year, so doctors recommend monitoring it yearly. 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 sensorimotor neuropathy.
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:
Several other illnesses can present with a monoclonal gammopathy, and the monoclonal protein may be the first discovery before a formal diagnosis is made:
Pathologically, the lesion in MGUS is in fact very similar to that in multiple myeloma. There is a predominance of clonal plasma cells in the bone marrow with an abnormal immunophenotype (CD38+ CD56+ CD19−) mixed in with cells of a normal phenotype (CD38+ CD56− CD19+); 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. What causes MGUS to transform into multiple myeloma is as yet unknown.
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