Identification of the phenotype of neoplastic cells infiltrating the skin. Top left panel (CD3) shows an area of affected skin stained with monoclonal antibodies against CD3. Clusters of CD3⁺ cells are present along the dermal-epidermal junction and in the epidermis. Top and lower right panels (high-and low-power magnification, respectively) demonstrate that the infiltrating cells belong to the CD8⁺ T-cell subgroup. Cells strongly positive for CD8 are present in clusters in the dermis along the dermal-epidermal junction and in the epidermis. Lower left panel is a control for antibody specificity.