Clinical Challenge: Dark Spots on the Arms

A 57-year-old woman presents with dark spots on her arms that she first noted several months ago. She denies itching and antecedent trauma. Medical history is positive for hypertension controlled with a thiazide diuretic. She has no history of skin cancer but admits to ample sun exposure. Examination reveals multiple nonblanchable, erythematous macules. The patient requested that a biopsy be ...