Expression of p53, p63, p16, Ki67, Cyclin D, Bcl-2, and CD31 Markers in Actinic Keratosis, In Situ Squamous Cell Carcinoma and Normal Sun-Exposed Skin of Elderly Patients

Background: Age and cumulative exposure to ultraviolet (UV) light are primary contributors to skin cancer development. Regulatory proteins within the cell cycle are essential for the homeostasis of squamous epithelium. Methods: This study assessed the expression of immunohistochemical markers p53, p63, p16, Ki67, Cyclin D, Bcl-2, and CD31 in keratinocyte intraepithelial neoplasia (actinic keratosis and squamous cell carcinoma in situ) compared to normal skin. The objective was to distinguish disease-specific changes from those attributable to ageing and sun exposure in elderly skin. Results. Analysis included 22 actinic keratoses (AK), 7 in situ squamous cell carcinomas (SCC), and 8 normal skin biopsies. The mean age was 78.1 years for the AK/SCC group and 73.8 years for controls, with no significant age difference noted between the groups. The AK/SCC group exhibited a higher occurrence of amorphous masses, higher intensity of p53, lower Bcl-2 expression in the epidermis, higher Bcl-2 expression in the dermis, and higher CD31 expression in the dermis, all of which were statistically significant (p < 0.05). Conclusions: The study identifies distinct differences in the presence of amorphous masses and the expression levels of p53, Bcl-2, and CD31 between sun-exposed skin and in situ cutaneous squamous cell carcinomas, including actinic keratoses.