Clonal rearrangements and Malignant Clones in Peripheral T-cell Lymphoma

Aim: To assess the feasibility and informative value of T-cell clonality testing in peripheral T-cell lymphoma (PTCL). Patients and methods: Biopsies of involved sites, blood, and bone marrow samples from 30 PTCL patients are included in the study. Rearranged TCRG and TCRB gene fragments were PCR-amplified according to the BIOMED-2 protocol and analyzed by capillary electrophoresis on ABI PRISM 3130 (Applied Biosystems). Results: TCRG and TCRB gene clonality assay was valuable in confirming diagnosis in 97% of PTCL patients. T-cell clonality assay performed on blood or bone marrow samples reaffirmed lymphoma in 93% of cases, whereas morphological methods were informative in 73% of cases only. We observed multiple TCRG and TCRB gene rearrangements, loss of certain clones in the course of the disease, as well as acquisition of new clones in 63% of PTCL cases, which can be attributed to the genetic instability of the tumor. Conclusion: TCRG and TCRB gene clonality assay is beneficial for the diagnosis of PTCL. However, the presence of multiple clonal rearrangements should be considered. Clonal evolution in PTCL, particularly acquisition of new clones, should not be treated as a second tumor. Multiple TCRG and TCRB gene rearrangements may interfere with minimal residual disease monitoring in PTCL.