The invention relates to a method and composition for treating aged or photo-damaged skin. In one embodiment, the invention includes using a composition comprising about 1% to about 2% of 1-isobutyl-1H-imidazo [4,5,-C] quinolin-4-amine in a topical preparation or cream. In further embodiments, the method includes identifying topical compositions that can diagnose or identify precancerous region of the skin, as well as methods for treating aged or photo-damaged skin by applying a Toll-like receptor activator, such as 1-isobutyl-1H-imidazo [4,5,-C] quinolin-4-amine.