Rearrangement of kappa-chain and T-cell receptor beta-chain genes in malignant lymphomas of "T-cell" phenotype.

Detection of immunoglobulin gene rearrangements by molecular hybridization is considered to be a highly sensitive approach to the evaluation of clonality of B-cell-derived neoplasms. Like monoclonal surface immunoglobulin in B cells, which serves as a reliable immunophenotypic marker for clonality, rearrangement of the genes encoding immunoglobulin light chains has been accepted as a reliable genotypic marker for the presence of a clonal expansion of B lymphocytes. The authors now report 3 cases of non-Hodgkin's lymphoma that were immunologically classified as having a T-cell phenotype and in which, in addition to rearrangements of the T-cell receptor beta-chain gene, a rearrangement of an immunoglobulin light-chain gene was clearly identified by Southern blot hybridization. The results demonstrate that the data obtained by molecular hybridization should be interpreted with caution when the immunogenetic findings do not correlate with immunophenotypic expression, and that the results of molecular genetics studies should be interpreted in conjunction with morphologic and immunologic findings.