[Physiopathology and clinical aspects of monoclonal IgM gammopathy].

Ten subjects with IgM monoclonal gammopathy were studied with particular references to their clinical pictures. In 7 cases, the M component was W's macroglobulinaemia (MW) and in 3 undetermined monoclonal gammopathy (UMG). Serum IgM was always greater than 2170 mg% in MW and greater than 1120 mg% in UMG. All patients were over 45. Haemorrhage and autoimmune phenomena were noted in 2/10 cases, and liver and spleen enlargement in 7/10, peripheral lymphocytosis in 5/10, marrow lymphoplasmacytosis in 7/10, and plasma hyperviscosity in 7/10. Beta-2-microglobulin (beta-2MG) was higher on average in the 7MW cases than in the 3 UMG. A monoclonal peak was observed casually in 2/10 and after it had been clinically suspected in 3/10. ESR was high in all cases. The clinical and laboratory data are interpreted in the light of the possible pathogenetic mechanism. In addition, stress is laid on their importance in the differentiation of these two forms of IgM monoclonal gammopathy.