Immunofluorescent and immunoperoxidase staining of antibodies to fibrous keratin. Improved sensitivity for detecting epidermal cancer cells.

Microscopically controlled surgery (Mohs' surgery) is a widely accepted technique because it provides total extirpation of skin tumors with maximum conservation of tissue. However, in poorly differentiated tumors it is often difficult microscopically to recognize individual tumor cells in the midst of an inflammatory cell infiltrate, in fibrotic tissue, in connective tissue around blood vessels, in nerve sheaths, and in fascial planes. We have developed techniques to differentiate tumor cells, derived from the epidermis, from the normal nonkeratinizing tissue of mesodermal origin or the inflammatory cell infiltrate. In frozen sections, indirect immunofluorescence techniques with polyclonal antibodies to fibrous keratin allowed rapid identification of tumor cells of basal and squamous cell carcinoma. Immunoperoxidase staining proved to be a remarkably sensitive method for the identification of such carcinoma cells in both frozen and paraffin-embedded sections. When used in combination with the precise mapping techniques of Mohs' surgery, these reliable and specific stains permitted greater accuracy in assessing the total resection of an invasive tumor.