Evaluation of the polymerase chain reaction-based T-cell receptor β clonality test in the diagnosis of early mycosis fungoides

Background: T-cell receptor (TCR) clonality may help establish a diagnosis of mycosis fungoides (MF). Routine clonality analysis is performed by using a polymerase chain reaction TCR- gamma assay, yet with this method, 10% to 50% of T-cell lymphomas escape detection. TCR- beta gene rearrangement is an additional assay. Data about its efficacy are controversial. Objective: To evaluate the role of TCR-beta assay in the diagnosis of early MF. Methods: A retrospective study of 61 skin biopsies, 20 from patients with MF, 30 from patients suspected to have early MF, and 11 from patients with chronic inflammatory skin disease. Results: Monoclonality was detected in 16 of 20 (80%) MF cases: 15 (75%) with TCR-beta and 12 (60%) with TCR-gamma assay. Of the 30 suspected cases of early MF, 14 showed monoclonality with TCR-beta, and only 5 of 14 showed monoclonality with TCR-gamma assay. None of the chronic inflammatory condition samples showed monoclonality. Therefore, TCR-beta clonality assay was more sensitive than TCR-gamma in early MF (83% vs 43%; P =.002). Limitations: This was a retrospective, relatively small study. Conclusion: TCR-beta showed a higher sensitivity rate compared with TCR-gamma in early-stage MF. The combined use of the TCR-beta and TCR-gamma clonality tests can significantly improve the diagnosis rate of early-stage MF.