A 67-year-old man comes to the clinic for evaluation of a "rough spot" on his right temple that he noticed several months ago. He has worked as a lifeguard for decades and rarely used sunscreen. The lesion is not painful and does not bleed. He denies fever or recent medication changes. Physical examination shows a 1-cm erythematous papule with a sandpaper-like texture and a yellow-to-brown, adherent scale on the right temple. No vesicles or pustules are present. Which of the following is the most likely diagnosis?