Cutaneous lymphocyte antigen expression in benign and neoplastic cutaneous B- and T-cell lymphoid infiltrates

Background: Cutaneous lymphocyte-associated antigen (CLA) is expressed in resident cutaneous T lymphocytes, high endothelial venules, peripheral monocytes, granulocytes and a small percentage of memory B cells. It has been postulated to be an important factor in homing of lymphocytes to the skin because of its function as a ligand for E-selectin expressed on cutaneous endothelial cells. Design: We investigated the expression of CLA using the HECA-452 antibody on paraffin-embedded, formalin-fixed tissue in a variety of reactive, neoplastic and preneoplastic cutaneous lymphoid infiltrates of T- and B-cell derivation. Results: CLA was expressed at high levels in various types of inflammatory dermatoses with the exception of lupus erythematosus. High levels of CLA expression were seen in epidermotropic T-cell dyscrasias and epidermotropic T-cell lymphomas including mycosis fungoides (MF) and adult T-cell leukemia/lymphoma (ATCLL). A loss of CLA in tumors normally positive for CLA was a feature of disease progression best exemplified by tumor-stage MF and acute ATCLL. There was a lack of CLA expression in those lymphocytic infiltrates manifesting subcutaneous localization including lupus profundus, panniculitis-like T-cell lymphoma and atypical lymphocytic lobular panniculitis. CLA expression was not only observed in primary cutaneous anaplastic large cell lymphoma but also seen in cases of nodal anaplastic large cell lymphoma secondarily involving the skin and was negative in cases of nodal anaplastic large cell lymphoma without any established skin involvement. An oligodot pattern defined a novel reaction pattern in those aggressive systemic dyscrasias with a proclivity to involve the skin. CLA was negative in the majority of B-cell lymphomas. Conclusions: CLA plays a role in the pattern of T-cell lymphocyte migration in the skin and subcutis in both reactive and neoplastic states. An alteration in the expression of this marker, whether it is in the context of the acquisition of expression in a cell that is normally CLA negative or its loss of expression, may define a key event in determining cutaneous and extracutaneous hematopoietic cell distribution.