Monoclonal gammopathy of undetermined significance (MGUS)

A paraproteinemia without evidence of a concurrent myeloma is called monoclonal gammopathy of undetermined significance (MGUS). It can develop eventually into a myeloma. According to the WHO classification, MGUS can be diagnosed if the following conditions are fulfilled:

• a paraproteinemia <30 g/L
• <10% clonal plasma cells in the bone marrow
• no organ symptoms (CRAB-criteria negative, CRAB = increased calcium level, renal dysfunction, anemia, destructive bone lesions)
• no other B-cell neoplasm.