A 32-year-old man complains about a dark patch on his left shoulder (Figure) that he says first appeared when he was an adolescent. It has not changed in size, shape, or color. He vaguely recalls seeing a physician around the time that it first appeared, but he does not remember what the physician thought of the lesion. He is now seeking a diagnosis and treatment. He dislikes the hair that grows within in the patch, and he has his wife shave it on occasion. He has no history of significant sun exposure or sunburn and no personal or family history of skin cancer.

What’s Your Diagnosis?

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