An actinic keratosis is a rough, scaly patch on the skin that develops from years of sun exposure. It's often found on the face, lips, ears, forearms, scalp, neck or back of the hands.
Also known as a solar keratosis, an actinic keratosis grows slowly and usually first appears in people over 40. You can reduce your risk of this skin condition by minimizing your sun exposure and protecting your skin from ultraviolet (UV) rays.
Left untreated, the risk of actinic keratosis turning into a type of skin cancer called squamous cell carcinoma is about 5% to 10%.
Cited from the Mayo Clinic & the American Academy of Dermatology