P21 Immunoexpression in Actinic Keratosis and Cutaneous Carcinomas.

Actinic keratosis is a precancerous lesion of the skin with variable rates of transformation into non-melanocytic carcinomas. The present study aims to analyze p21 expression in actinic keratosis and cutaneous squamous carcinomas. P21 expression analysis revealed a positive reaction in 63 (71.4%) of the investigated cases. The immunostaining analysis revealed positivity in 82.1% of the studied actinic keratosis cases and in 43.9% of the investigated carcinomas. High scores of immunoreactions were identified only for the well-differentiated and for the carcinomas in initial stages. Association of p21 expression with pre-invasive or well-differentiated invasive lesions in early stages of tumor progression suggests that p21 may be an early event in squamous carcinogenesis.