Diseases & Conditions
What are Actinic Keratoses?
Actinic keratoses (AKs) are dry, scaly, rough-textured patches or lesions that form on the outermost layer of the skin after years of exposure to ultraviolet (UV) light, such as sunlight. These lesions typically range in color from skin-toned to reddish brown and in size from that of a pinhead to larger than a quarter. Occasionally, a lesion grows to resemble an animal horn and is called a “cutaneous horn.”
It is important that anyone with AKs be under a dermatologist’s care. AKs are considered the earliest stage in the development of skin cancer and have the potential to progress to squamous cell carcinoma, a type of skin cancer that can be fatal. Anyone who develops AKs has extensive sun-damaged skin. This makes one more susceptible to other forms of skin cancer, including melanoma. Melanoma is considered the most lethal form of skin cancer because it can rapidly spread to the lymph system and internal organs.
Years of sun exposure cause AKs to develop. All AKs, including actinic cheilitis, develop in the skin cells called the “keratinocytes,” which are the tough-walled cells that make up 90% of the epidermis, the outermost layer of skin, and give the skin its texture. Years of sun exposure cause these cells to change in size, shape, and the way they are organized. Cellular damage can even extend to the dermis, the layer of skin beneath the epidermis.
Who Gets Actinic Keratoses?
Individuals with fair skin, a history of cumulative sun exposure, or a weak immune system are at greatest risk for developing AKs. These lesions develop on areas of the body that have received years of sun exposure, such as the face, ears, lip, scalp, neck, forearms, and back of the hands. AKs usually appear after age 40 because they take years to develop. However, even teens can have AKs when they live in areas that receive high-intensity sunlight year round, such as Florida and Southern California.
Research shows that p53, a mutant protein found in sun-damaged cells in the body, is present in more than 90% of people who have AKs and squamous cell carcinomas.