Multiclonal cases with coexisting B-cell clones sharing HCDR3 features (A). Multiclonal (B) and monoclonal (C) cases with B-cell clones showing stereotyped HCDR3 amino acid sequences. A. Multiclonal cases with coexisting B-cell clones showing HCDR3 regions of identical length or differing by one amino acid, and analogous composition of amino acids in some parallel positions.