Actinic (or solar) keratosis is a premalignant epithelial lesion that is directly related to long-term sun exposure.
These lesions are classically found on the vermilion border of the lower lip as well as on other sun-exposed areas of the skin. A small percentage of these lesions will transform into squamous cell carcinoma.Biopsies should be performed on
lesions that repeatedly ulcerate, crust over, or show a thickened white area. These lesions are commonly found in individuals with extensive sun exposure, such as those with outdoor occupations and/or fair complexions.These lesions are classically found on the vermilion border of the lower lip as well as on other sun-exposed areas of the skin. A small percentage of these lesions will transform into squamous cell carcinoma.Biopsies should be performed on
TYPICAL FEATURESActinic keratosis may be seen on the skin of the forehead, cheeks, ears, and forearms. On the lip, it appears as a white plaque, oval to linear in shape, usually measuring < 1 cm in size (Figure 58). The surface may be crusted and rough to the touch. Histopathologically, the surface epithelium appears atrophic, with a basophilic homogenous amorphous alteration of the collagen (solar elastosis) in the lamina propria. Varying degrees of atypical features such as increased nucleocytoplasmic ratios, loss of cellular polarity and orientation, and nuclear and cellular atypia are found within the epithelium. A mild lymphocytic infiltrate may also be noted in the lamina propria.
TREATMENT AND PROGNOSISThe mainstay of treatment of actinic keratosis is surgery. Chemotherapeutic agents such as topical 5-fluorouracil have been used with some success.However, follow-up biopsies in individuals who were treated with 5-fluorouracil showed that the dysplastic changes persist in clinically healthy-appearing epithelium. Patients treated with nonsurgical methods therefore require long-term follow-up. About 10% of these lesions will undergo malignant transformation.