From the American Academy of Dermatology website:
“Sun damage is also called solar keratosis. It forms when the skin is badly damaged by ultraviolet (UV) rays from the sun or indoor tanning. Most people get more than one SK. When you have more than one SK, you have soloar keratoses, or SKs.
Anyone who has many SKs should be under a dermatologist’s care. Most people who have many SKs continue to get new SKs for life. SKs are considered precancerous. Left untreated, SKs may turn into a type of skin cancer called squamous cell carcinoma.
By seeing a dermatologist for checkups, the SKs can be treated before they become skin cancer. If skin cancer does develop, it can be caught early when treatment often cures skin cancer.