Distribution of keratin proteins in neoplastic and tumorlike lesions of squamous epithelium: An immunohistochemical study

Seventy-six cases of tumorlike and neoplastic lesions from epidermis and oral epithelium were analyzed by a histochemical technique for the demonstration of keratin. Formalin-fixed paraffin sections were reacted with rabbit antihuman keratin antiserum (dilution of 1:40). The types of distribution of keratin in cells of lesions were classified into five categories: (1) regional, as found in normal squamous epithelia and benign hyperkeratinized lesions, and papilloma, and keratinized squamous cell carcinoma; (2) total, as seen in intensely keratinized lesions, such as verruca vulgaris and highly keratinized squamous cell carcinoma; (3) negative, as displayed by basal cell carcinoma; (4) scattered, as in the most poorly differentiated squamous cell carcinomas; and (5) mixed cellular, as found in both poorly and moderately differentiated squamous cell carcinomas.