An 11-year-old girl is brought in by her parents, who are concerned by the presence of brown spots all over her body.
The spots have been present since birth, but were few and small then. Over the years, they have progressively increased in size and number. They are not itchy or painful, and are concentrated over the torso.
She is otherwise healthy with no history of convulsions, headaches, blurred vision, bone pain or previous medication use. There is no family history of similar conditions.