Lymphoid tumors displaying rearrangements of both immunoglobulin and T cell receptor genes

Ig and T(β) gene rearrangements can be used as genetic markers of lineage and clonality in the study of B and T cell populations. We have addressed the issue of the respective B and T lineage specificity of these rearrangements by analyzing a panel of 63 lymphoid tumors representative of the various clinicopathologic categories of both B and T neoplasias. We report that ~10% of the cases tested displayed rearrangements of both Ig and T(β) genes. Despite their dual genotypic pattern, these tumors retain a pure immunophenotype, i.e. they display either B or T cell lineage-restricted cell surface antigens. The implications of these findings for both normal and neoplastic lymphoid differentiation are discussed.