A 15-year-old Caucasian boy presented for evaluation of an asymptomatic brown patch on his right shoulder. While the patient’s mother first noticed the patch when he was 5 years old, the discolored area had recently been expanding in size and had developed hypertrichosis. The patient was otherwise healthy; he took no medications and denied any symptoms or history of trauma to the area. None of his siblings were similarly affected.
A physical examination revealed a well-demarcated hyperpigmented patch with an irregularly shaped border and an increased number of terminal hairs (FIGURE 1). The affected area was not indurated, and there were no muscular or skeletal abnormalities on inspection. Examination of the patch under a dermatoscope revealed islands of reticular (lattice-like) hyperpigmentation, focal hypopigmentation, and prominent follicles (FIGURE 2).