An assessment of the malignant potential of actinic keratoses and Bowen's disease: p53 and PCNA expression pattern correlate with the number of desmosomes.

Actinic keratoses (AK) and Bowen's disease (BD), both intraepidermal skin tumors, have a potential progression to squamous cell carcinoma (SCC). To evaluate the malignant potential of AK and BD, the expression pattern of p53 protein and proliferating cell nuclear antigen (PCNA) were examined in five types of AK and BD by immunohistochemistry. The ultrastructural difference of epidermal cells between AK and BD lesions was investigated. In the study of p53 and PCNA expression, the atrophic and acantholytic types of AK showed lower positive rates compared to others. These two types did not demonstrate all layers expression pattern. The number of desmosomes of the epidermal cells was significantly reduced in BD, and in the bowenoid and hypertrophic types of AK compared with other types of AK The number of hemi-desmosomes showed greatest reduction in BD and the bowenoid type of AK On the basis of our findings, it is hypothesized that atrophic and acantholytic types of AK may have the lowest, and the bowenoid type of AK and BD may have the highest, malignant potential.