Derm Dx: Hyperpigmented Macule on the Abdomen

An 11-year-old adolescent is brought to the office for treatment of low-grade acne that affects her face and back. Upon examination, a sizable hyperpigmented macule is identified on her abdomen that has been present for approximately 2 years. No other members of her family have similar lesions, and family history is negative for skin cancer (including melanoma). Can you diagnose ...