PROLIFERATIVE ACTINIC KERATOSIS

Background. Solar/actìnic keratoses (AKS) are premalignant lesions, usually less than 1 cm in diameter, that appear on chronically sun‐damaged skin. Methods. We describe four patients with a form of AK that enlarged 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 present over a large area. Results. Three of the patients developed either a squamous cell carcinoma (sec) or basal cell carcinoma (see) within the area encompassed by the AK. Conclusions. These cases represent an insidious, proliferative form of AK with an increased tendency to develop into skin cancer.