A 60-year-old farmer presents with multiple patches of discoloration on his face. Biopsy of lesional skin reveals actinic keratosis. Which of the following terms best describes this response of the skin to chronic sunlight exposure?

Dysplasia. Actinic keratosis is a form of dysplasia in sun-exposed skin. Histologically, such lesions are composed of atypical squamous cells, which vary in size and shape. They show no signs of regular maturation as the cells move from the basal layer of the epidermis to the surface. Dysplasia is a preneoplastic lesion, in the sense that it is a necessary stage in the multistep evolution to cancer. However, unlike cancer cells, dysplastic cells are not entirely autonomous, and the histologic appearance of the tissue may still revert to normal. None of the other choices represent preneoplastic changes in sun-exposed skin.Diagnosis: Actinic keratosis, dysplasia