Intraepidermal localization of the clone in cutaneous T-cell lymphoma.

BACKGROUND: No immunohistologic techniques are currently available to demonstrate clonality of T-cell lymphomas. Monoclonal antibodies to the variable region of the T-cell receptor (TCR) have been produced that identify minor populations of normal peripheral blood T lymphocytes. OBJECTIVE: We investigated the expression of TCR V-region genes in cutaneous lymphomas to determine whether immunostaining with these antibodies may be a simple method to detect clonal T-cell proliferations and help to distinguish benign lymphoid infiltrates from malignant lymphoma. METHODS: Cutaneous samples were obtained from 18 cutaneous T-cell lymphomas (14 mycosis fungoides, 1 Sézary syndrome, 2 pleomorphic T-cell lymphoma, and 1 large cell anaplastic lymphoma) and 8 benign lymphoid infiltrates. Frozen sections were incubated with monoclonal antibodies and stained by the alkaline phosphatase-antialkaline phosphatase technique. Staining was performed with a panel of 7 anti-TCR V-region antibodies, 6 T-cell markers, 1 anti-beta chain antibody, and 1 anti-delta chain antibody. RESULTS: Clonality could be demonstrated in 2 of 18 cutaneous lymphomas. We observed the strictly intraepidermal localization of clonal proliferation in one case of early-stage mycosis fungoides. CONCLUSION: Anti-TCR V-region antibodies may identify a strictly epidermotropic clone in early mycosis fungoides. However, the panel of antibodies currently available stains only a minority of cutaneous T-cell lymphomas. The usefulness of these antibodies as a clonotypic marker needs to be reevaluated when a larger panel of antibodies becomes available.