Essential monoclonal gammopathy with an IgM paraprotein that is a cryoglobulin with cold agglutinin and EDTA-dependent platelet antibody properties.

A patient with apparent anaemia and thrombocytopenia caused by a monoclonal paraprotein is described. The patient's serum contained a monoclonal IgM kappa, a cryoglobulin and a cold agglutinin. The cryoglobulin, similar to the serum paraprotein, was a monoclonal IgM kappa. Serum was studied to determine the relationship of the cryoglobulin with the cold agglutinin. The cryoglobulin and cold agglutinin were found to be the same paraprotein. Moreover, with absorption and elution techniques the reactivity of the autoantibody with both erythrocytes and platelets was demonstrated. Reports of cryoprecipitable cold agglutinins are rare and therefore this case is exceptional given that the IgM kappa paraprotein was found to be a cold agglutinin which was also reactive with platelets.