Diagnostic value of T-cell receptor γ gene rearrangement in T-cell neoplasms

Background: The discrimination between reactive and malignant cell populations in some patients with suspected T-cell lymphoproliferative disorders can be complicated and less straightforward. Often, the dilemma lies in determining whether a population of lymphocytes is reactive or neoplastic. In such cases, T-cell receptor (TCR) gene clonality studies have proved useful as an additional diagnostic tool. The TCRc gene is a preferred target for TCR gene clonality as it is rearranged at an early stage of T lymphoid development, rearranged in a large percent of T-cell neoplasms, and also because of its relative structural simplicity. Materials and methods: In the present study, we used the BIOMED-2 multiplex primer panel to assess the value of TCR_γ gene rearrangement using genescan analysis in 30 patients with suspected T-cell neoplasms and to elucidate its possible role in the diagnosis of such disorders. Results: TCR_γ gene clonality was detected in all 18 patients with suspected T-cell acute lymphoblastic leukemia/lymphoblastic lymphoma. In contrast, it was detected in nine out of 12 patients (75%) with suspected peripheral T-cell lymphoma. It is known that TCRc monoclonality in peripheral T-cell lymphoma can be detected in patients with more aggressive disease in terms of both clinical presentation and laboratory results. V_γfI was the most frequently used V_γ segment in our patients. The sensitivity and specificity of genescan were found to be 0.89 and 0.67, respectively, as compared with histopathology. Conclusion: It is concluded that TCR_γ gene clonality is a very useful diagnostic tool in T-cell neoplasms. As it is relatively simple, it can be used as a preliminary test for clonality assessment, followed by the more complex TCR_β gene rearrangement only in negative cases to improve sensitivity. In addition, it should be used together with heteroduplex and interpreted within the clinical context to improve its specificity.