Analysis of the immunoglobulin heavy chain gene of secondary diffuse large B‐cell lymphoma that subsequently developed in four cases with B‐cell chronic lymphocytic leukemia or lymphoplasmacytoid lymphoma (Richter syndrome)

Abstract

The immunoglobulin heavy chain gene (IgH gene) was analysed in four cases of B-cell Richter syndrome, in order to determine whether a secondary diffuse large B-cell lymphoma (DLBCL) could arise from the same clone as the initial B-cell chronic lymphocytic leukemia (B-CLL) and lymphoplasmacytoid lymphoma (LPL) or be a de novo event, and whether secondary DLBCL shows an intraclonal microheterogeneity. Both the initial B-CLL and secondary DLBCL in two cases expressed CD5 antigen. Both samples of the initial B-CLL or LPL and the secondary DLBCL in three cases were examined for comparison. The polymerase chain reaction-amplified IgH gene of secondary DLBCL in two cases (CD5+ case and CD5- case) were different from those of the initial B-CLL, revealing a new malignant clone. The other case (CD5-) showed that secondary DLBCL had a sequence identical to the initial LPL, indicating the same clonal origin. The variable region of the IgH gene of secondary DLBCL (CD5+ two cases and CD5- two cases) exhibited a 0.5-9.0% somatic mutation range and no intraclonal microheterogeneity.