[Monoclonal gammopathy of undetermined significance and multiple myeloma].

In rheumatological practice monoclonal gammopathy of undetermined significance (MGUS) is a common incidental finding. Several rheumatic inflammatory diseases are known to have an elevated risk of MGUS, which can evolve into multiple myeloma or other lymphatic malignancies. The relevant definitions of disease entities are described, as well as algorithms for further diagnostic work-up and follow-up for monoclonal gammopathy, depending on the risk of progression. Therapeutic strategies against multiple myeloma are presented. Some of these therapeutic modalities could play a future role in treating plasma cell-dominated autoimmune diseases.