Restricted <scp>TRBC1</scp> expression: A clonality marker for circulating <scp>Sézary</scp> cells

A 56-year-old woman presented with diffuse xerotic cutaneous plaques and lymphadenopathy. Her peripheral count showed marked lymphocytosis (white cell 31.8 × 109/L), mild anemia (hemoglobin 10.7 g/dl), thrombocytosis (platelet 483 109/L). blood smear demonstrated numerous small to medium-sized lymphocytes significantly irregular nuclei, delicately folded/cerebriform nuclei (Sézary cells) (Image 1A). Flow cytometric immunophenotyping on sample a 62% population of neoplastic T cells aberrant immunophenotype CD3+/CD4+/CD7−/CD8−/CD25−/CD26−/TCRαβ+/TCRγδ− restricted TRBC1 expression (in contrast normal polytypic pattern, Image 1B). Polymerase chain reaction (PCR) analysis revealed monoclonal T-cell receptor gamma gene rearrangement. Serology for HTLV-1 was negative. concurrent skin biopsy displayed CD4 positive lymphoma the similar immunophenotype. The overall findings are diagnostic Sézary syndrome involving skin. Use an antibody against β constant region 1 (TRBC1) has recently been described assess clonality TCRαβ subsets, as randomly express one two mutually exclusive (TRBC) regions, or TRBC2. This novel strategy detecting clonality, analogous assessment κ- λ-immunoglobulin light chains in B-cell lymphoma, is useful diagnosis syndrome, particularly helpful cases where follow-up cases. authors declare no conflict interest. data that support this study available from corresponding author upon reasonable request.