Roger, a 40-year-old man who loves spending time on the beach, is complaining to you that his suntan made him popular when he was young—but now his face is all wrinkled, and he has several darkly...

Roger, a 40-year-old man who loves spending time on the beach, is complaining to you that his suntan made him popular when he was young—but now his face is all wrinkled, and he has several darkly pigmented moles that are growing rapidly and are as big as large coins. He shows you the moles, and immediately you think “ABCDE.” What does that mean, and why should he be concerned?