The real‐world application of T‐cell receptor constant beta‐1 chain antibody assay in cutaneous T‐cell lymphoma

Identifying aberrant T lymphocytes in peripheral blood is essential for diagnosing Sezary syndrome (SS) and is a prognostic indicator in mycosis fungoides (MF). Flow cytometry using a T-cell receptor constant beta-1 chain (TRBC1)-targeting antibody provides a refined approach for detecting T-cell clonality. We evaluated the performance of the TRBC1 antibody assay (TRBC1-aa) in 164 patients, compared to standard flow cytometry methods for assessing T-cell aberrancy, demonstrating 92.3% sensitivity and 83.5% specificity. TRBC1-aa accurately excluded clonality in 100% of benign inflammatory dermatoses and improved the detection of residual blood involvement earlier than standard flow cytometry in 66.7% of SS and 25.0% of advanced-stage MF patients on systemic therapy.