Abstract
BACKGROUND: The monoclonal gammopathies are a group of plasma-cell proliferative disorders characterized by the secretion of monoclonal immunoglobulin (M protein or paraprotein). Some rare cases have revealed the specific affinity of paraprotein as autoantibody. Here we report a patient with monoclonal gammopathy of undetermined significance (MGUS) accompanied by a remarkable increase of anticardiolipin antibody (aCL) and an extensively decreased coagulation factor activity, however, without any clinical signs of antiphospholipid syndrome (APS) and bleeding. RESULTS: Our further investigation indicated that IgMκ paraprotein of this patient possessed an antibody activity against phospholipids so as to bind to cardiolipin and interfere with coagulation assay in vitro. CONCLUSIONS: This case might be indicative that an abnormality of coagulation tests, disturbed by IgMκ paraprotein, does not predict a risk of bleeding in this patient.