PROLIFERATIVE ACTINIC KERATOSIS

Background. Solar/actinic keratoses (AKS) are premalignant lesions, us ually less than 1 cm in diameter, that appear on chronically sun-damag ed skin. Methods. We describe four patients with a form Of AK that enl arged and recurred despite standard treatment. Histologic examination revealed a single and multilayered sheet of anaplastic cells along the undersurface of the epidermis extending down hair follicles and prese nt over a large area. Results. Three of the patients developed either a squamous cell carcinoma (scc) or basal cell carcinoma (BCC) within t he area encompassed by the AK. Conclusions. These cases represent an i nsidious, proliferative form of AK with an increased tendency to devel op into skin cancer.