Actinic keratoses
The most important cause of these premalignant lesions is too much exposure to ultraviolet light from the sun or other sources. This can cause the DNA of skin cells (keratinocytes) in the outer layer of the skin (the epidermis) to change. Sometimes this alteration in DNA allows the skin cells to grow out of control and develop into a scaly area called an actinic keratosis or Bowen’s disease. We see them most commonly over the hands, forearms, face, bald areas of the scalp and even along the rim of the ear. It is common to find actinic keratoses to be more pronounced over the right side of the face and right arm due to exposure to UV through the window of your car!
Not only are they a marker of intensive UV exposure but they can also evolve into a squamous cell carcinoma if they are not treated. On average 10% of actinic keratoses develop into a skin cancer.
