Klin Onkol 2025; 38(5): 336-344. DOI: 10.48095/ccko2025336.
Background: The group of monoclonal gammopathies includes both malignant diseases, such as multiple myeloma and Waldenström‘s macroglobulinemia, and benign proliferations of plasma cells or lymphoplasmacytic cells with the formation of usually low concentrations of monoclonal immunoglobulin and/or free light chains. The term monoclonal gammopathy of undetermined significance (MGUS) is used for conditions with non-malignant proliferation. Aim: In the last 25 years, understanding of the various forms of diseases caused by products of benign lymphoplasmacytic or plasma cell proliferation has significantly increased. The following terms have been used for them: monoclonal gammopathy of renal significance, monoclonal gammopathy of cutaneous significance, monoclonal gammopathy of neurological significance. In the years 2018–2020, the international hematology community accepted the group name monoclonal gammopathy of clinical significance for all conditions in which organ damage is etiopathogenetically related to the products (MGCS) of these cell clones. The text presents an overview of all clinical units that belong to this group and briefly discusses the etiopathogenesis and therapy of these diseases. Conclusion: MGCS is a new term that deserves to be incorporated into the new International Classification of Diseases, which would help improve epidemiological information about these very rare diseases. The same drugs used to treat malignant gammopathies are used in the treatment of MGCS. Patients with MGCS are discriminated, because their diagnoses are not included in the registration studies of new drugs. Therefore, targeted treatment can only be used with the approval of the healthcare payer.