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The main thing that bothers me about this question is that if it is indeed nevus simplex, it's definitely a very non-typical presentation. Nevus simplex most commonly occurs on he back of the neck/midline locations plus they are pink in color.
The lesion described in this question is purplish (not pink) and it appears on the right side of the face (ie. neither back of neck nor midline). We can definitely rule out nevus flammeus because that is only seen in the setting of Sturge-Weber syndrome, which this patient has no signs of. We can also rule out strawberry hemangioma because such a lesion would be raised, not flat.