Interestingly, in half of the discrepant IgM-MGUS cases, cPC coexisted with cB-lymphocytes with a WM-like immunophenotype (8/16, 50%), while the other discrepant MGUS cases (11/19, 58%) included 8/16 IgM-MGUS in whom cPC could not be detected in BM nor in blood, either in the absence of other cB-cells (4/8, 50%) or in the presence of CLL-like or non CLL-like MBL cB-lymphocytes (4/8, 50%). This evidence concerns the gene CD40LG and B-cell chronic lymphocytic leukemia.