Large patch of coalescing gray-brown macules

A 14-year-old Hispanic male presents with a three-month history of a slowly enlarging "rash" on his chest and back. He denies associated pain or pruritus. The patient is overweight but has no known medical problems otherwise and takes no medications. Examination of the rash reveals gray-brown macules that coalesce into a large patch involving the chest, intermammary cleft, shoulders, and ...