Actinic Keratosis Introduction
Actinic keratoses are very common. They are firm, keratotic lesion, usually found in sun-exposed areas. Actinic keratoses are precursors to squamous cell carcinoma, thus, they have malignant potential. They are caused by years of cumulative sun exposure, leading to DNA damage of keratinocytes. Roughly 5 to10% of actinic keratoses progress to invasive squamous cell carcinoma over several years. Although spontaneous regression of actinic keratoses can occur, the biologic behavior of each actinic keratosis cannot be predicted, thus, every lesion is treated as a precursor lesion.
Individual actinic keratoses become progressively more common after 40 years of age and are more common in lighter skin types. They occur along with other signs of sun damage, such as atrophy, uneven pigmentation and telangiectasias. They are predominately found on the face, scalp, ears and neck, as well as the dorsal hands. The lower lip equivalent to an actinic keratosis is called actinic cheilitis.