Serum double monoclonal components and hematological malignancies: only a casual association? Review of 34 cases.

A double monoclonal component (MC) detected in the serum and/or urine represents a very rare occurrence (2-6% of monoclonal gammopathies). In this study, we report 34 patients with double serum MCs, focusing on the associated diseases. The diagnosis was made using high-resolution serum protein electrophoresis and immunofixation. Of the 1214 patients with monoclonal gammopathies, 49 had a double MC but only 34 (2.8%) were included in our study. A double MC was associated with hematological malignancies in 20/34 cases. Based on our experience, a double MC is more often associated with other diseases, especially an oncohematological one.