A single clonal origin of neoplastic B cells in a patient with CD5+B-intermediate lymphocytic lymphoma terminating in...

To investigate the clonal origin of a case of CD5+B-intermediate lymphocytic lymphoma terminating in plasmacytoid differentiation, we analyzed the immunophenotype and immunoglobulin gene rearrangements in the first and second lymph nodes from which biopsy specimens were taken. Immunohistochemical study revealed that both neoplasms have the same immunoglobulin light chain type (kappa-light chain). Immunoglobulin gene analysis using the Southern blot method revealed the identical immunoglobulin heavy chain and kappa-light chain gene rearrangements in both neoplasms. These findings suggest that both neoplasms are derived from a single clonal B cell. The present case may help a further understanding of CD5+B-lymphocyte differentiation pathway.