A 58-year-old man comes to the office due to progressive skin depigmentation, which started five years ago. He initially had a small patch over the face but gradually became widespread. The lesion is now present over the face, neck, hands, and feet. However, the patient has no pain or itchiness. Medical history is significant for hypertension, type 2 diabetes, and rheumatoid arthritis. The patient drinks beer once or twice a week but does not use tobacco or illicit drugs. Temperature is 37.2 C ( 98.9 F), blood pressure is 130/80 mm of Hg, the pulse is 77/min, and respirations are 22/min. The cardiopulmonary examination is unremarkable. Skin examination reveals multiple areas of depigmentation shown in the exhibit.