What does a precancerous cell look like, on your skin?

Cells are...: ...Microscopic; they are not visible with the naked eye. Under a microscope, various characteristics suggest a precancerous condition. A bunch of those cells gathered together can be visible to the naked eye as a precancerous tumor -- but it takes years of experience to identify them reliably.

Actinic keratosis: Actinic keratosis (solar keratosis) these small, scaly patches are caused by too much sun, and commonly occur on the head, neck, or hands, but can be found elsewhere. They can be an early warning sign of skin cancer. Most doctors recommend early treatment to prevent actinic keratosis of turning into skin cancer.