A 25-year-old African-American woman presents for evaluation of an asymptomatic rash she has had for several months. It manifested shortly after she began an exercise program to help her lose weight. Her primary care provider made a presumptive diagnosis of tinea versicolor (TV), but the rash persists despite treatment attempts with topical selenium sulfide shampoo and a 10-day course of fluconazole (200 mg/d).
The patient denies having endocrine problems, such as diabetes. However, she states that given her weight and family history, she was warned about the possibility.
EXAMINATION
The patient is obese and has type V skin. Her rash is dark brown and feels slightly rough. It appears solid brown on the central back and chest, peripherally becoming sparser and more reticular (net-like). It extends to involve the flexural surfaces of both arms.
What is the diagnosis?