Cutaneous lymphoid hyperplasia: Immunologic characteristics and assessment of criteria recently proposed as diagnostic of malignant lymphoma

Fifteen cases of cutaneous lymphoid hyperplasia were studied immunohistologically with a large panel of monoclonal antibodies to determine their immunoarchitectural composition and to determine whether immunologic criteria recently proposed to identify lymphoma ever occur in benign skin lesions. All lesions were composed of T cells, polytypic B cells, macrophages, and Langerhans cells. Although only six cases containing lymphoid follicles were recognized in routinely stained sections, an additional five were identified in immunoperox-idase-stained sections. These follicles were of both the primary and secondary types and contained dendritic reticulum cell networks. The immunophenotypic features of these follicles were similar to those of reactive f ollicles in lymphoid organs and contrasted sharply with those reported previously for follicular lymphomas. Helper T cells were predominant in 11 cases. With regard to proposed criteria for T cell lymphoma, we did not detect loss of pan T cell antigens CD2, CD3, CD5, or BF-1, nor did we find populations of T cells with abnormal co-expression or loss of subset antigens such as CD4^-8^- or CD4⁺8⁺. Two cases in which relatively sparse infiltrates were present, however, were moderately CD7-deficient. This finding suggests that the CD7 criterion for cutaneous T cell neoplasia be modified in this situation. As observed previously, Leu-8 antigen deficiency was a common, nonspecific finding. With regard to proposed criteria for B cell lymphoma, we did not detect populations of B cells that were immunoglobulin-negative, nor did we observe preferential loss of one or more B-lineage antigens, histocompatibility complex-associated antigens, or lymphocyte function-associated antigens. We also did not identify any CD5⁺ B cells. On the basis of a comparison of our current data with prior studies of cutaneous lymphomas, we conclude that the immunologic findings recently proposed as general criteria for the differentiation of lymphoma from lymphoid hyperplasia are, in fact, applicable to cutaneous lymphoid lesions.