The characteristics of human papillomavirus expression and cell proliferation in actinic keratosis and Bowen's disease of the skin.

The aim of our study was to elucidate the characteristics of HPV expression and cell proliferation in actinic keratosis and Bowen's disease of the skin. We examined immunocompetent patients with premalignant lesions of the skin such as actinic keratosis and Bowen's disease. 10 patients were involved in each group. Clinical study included gross features of lesion, growth rate, colour, size. Paraffin sections from biopsy specimens were were stained by hematoxylin-eosin and von Gieson. Immunohistochemistry was performed using monoclonal antibodies against HPV, oncoprotein p53, anti-apoptotic protein Bcl-2, proliferation marker PCNA. Strongly, moderately and weakly positive cells were counted. Actinic keratosis and Bowen's disease failed to show the specific clinical features, therefore, they can not be diagnosed based on clinical signs only and morphological examination seems to be mandatory. The immunohistochemical study has showed that in both actinic keratosis and Bowen's disease HPV was positive in 60%, and 40% were HPV-negative suggesting the similar incidence of HPV infection in these premalignant lesions. Our results suggest that HPV(+)/p53(+) types of actinic keratosis and Bowen's disease are characterized by higher proliferation activity in comparison to HPV(-)/p53(+) types, and expression of Bcl-2 is associated with HPV-negativity, therefore, these premalignant lesions of the skin require immunohistochemical examination with evaluation of expressions of human papillomavirus, proliferation marker PCNA and anti-apoptotic protein Bcl-2. The differential diagnosis of actinic keratosis and Bowen's disease should be based on the following immunohistochemical criteria: incidences of positivity for p53, Bcl-2 and PCNA are similar, but expression intensity and anatomical localization are different: their expressions are higher in Bowen's disease, positive cells are found primarily in upper epidermis in actinic keratosis, while whole epithelium is involved in Bowen's disease.