Immunohistochemical localization of keratins and involucrin in solar keratosis and Bowen's disease.

The present study was conducted to determine the patterns of immunohistochemical characterization of keratin (K) and involucrin in solar keratosis and Bowen's disease in order to clarify the abnormal differentiation or maturation of the tumor cells in these precancerous epithelial dermatoses. Seventeen human anti-cytokeratin antibodies and an anti-involucrin antibody were used to examine 15 cases of solar keratosis and 18 cases of Bowen's disease. Formalin-fixed and paraffin-embedded sections were stained with these antibodies by the avidin-biotin-peroxidase technique. In solar keratosis, keratin and involucrin distribution was similar to that in normal epidermis, whereas in Bowen's disease the keratin distribution varied among individual cases. The dyskeratotic cells in Bowen's disease showed a reduction or loss of staining with these antibodies, and they were occasionally positive for keratin 19. These observations suggest that there is a difference in keratin and involucrin expression between solar keratosis and Bowen's disease and that the atypical cells of Bowen's disease exhibit a diversity of differentiation.