A 23-year-old Asian woman came to the dermatology clinic for evaluation of an occasionally pruritic lesion that had been present on her right upper back for 10 years. After making its appearance, the lesion grew slowly for a short time, but the patient had noted no change in color or size over the past few years. Examination found no birthmarks, increased hair growth, or abnormalities of her right breast, shoulder, or arm. She was not using any oral or topical medications. The woman’s medical and family histories were unremarkable.