Expression of a cell-cycle-associated nuclear antigen (Ki-67) in cutaneous lymphoid infiltrates.

Cryostat sections of skin biopsies from 83 patients with benign or malignant cutaneous lymphoid infiltrates were examined immunohistologically for reactivity with Ki-67 (a monoclonal antibody recognizing a nuclear antigen expressed by cycling cells) using the APAAP immunoalkaline phosphatase labeling method and a double immunoperoxidase/alkaline phosphatase staining technique. Ki-67-positive neoplastic lymphocytes were plentiful in all large-cell lymphoma cases and in one-third of the small-cell lymphomas. Some benign disorders (patch test biopsies, cutaneous lymphocytoma, lichen planus) also contained many Ki-67-positive lymphocytes. These data indicate the value of using Ki-67 to assess the proliferative capacities of the lymphoid cells in cutaneous infiltrates. Use of this technique in the future may have important prognostic and therapeutic implications in the management of cutaneous lymphoid malignancies.