[Monoclonal gammopathies of undetermined significance].

Monoclonal gammopathy of undetermined significance (MGUS) is the most common type of monoclonal gammopathies. Genetic changes, various cytokines and bone marrow angiogenesis play an important role in the pathogenesis. As far as the malignant transformation of MGUS is concerned, size and type of the serum M-protein, serum kappa and lambda free light chain ratio and number of plasma cells in peripheral blood seem to play a predictive role.