Thank you for your answer! I would check if it is a real sunburn, or if it has been there since birth which might be a facial angioma, or a nevus. It is due to post inflammatory hyperpigmentation. Anyway there are a lot of procedures you can do in a dermatologist office, from chemical peels (glycolic, TCA), to fractional laser resurfacing, microneedling and PRP injections. First i would suggests to my patient start with a bleaching agent at bedtime, such Mela Cream Dermaceutic, or Yellow cream Dermaceutic. There is also a prescribtion drug Tri Luma, so you can talk with your treating physician. I let my patient use this product at home, always protecting the skin from the sun with a product with SPF 20 or higher in order to avoid further hyperpigmentation. After a month the patients starts the in office procedures depending on the age and skin phototype. I hope this helps. Feel free to ask me again.