There are gradually increasing light patches on the chin area. What would it be?

Hello,

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Perioral hypopigmentation in your age group is most likely because of a condition known as Pityriasis alba which is seen commonly as light patches on the face. It is common in patients with dry skin, tendency to have more allergies like rhinitis, recurrent cold, etc. You need to apply a moisturizer regularly for this. Apply Cetaphil moisturizing cream twice a day. I am sure it is not vitiligo. Other possibilities may be seborrheic dermatitis if with itching and scaling or simply post inflammatory hypopigmentation but not vitiligo.