Thanks for your question! Various infections can cause localized changes in skin color. You may have something called Tinea Versicolor, it is a type of dermatomycosis that is caused by a yeast that interferes with normal tanning. Dermatomycosis is a term that includes a variety of superficial skin infections caused by fungi or yeast. These types of infections almost always only affect skin, hair, and/or nails. It usually affects the back, upper arms, underarms, chest, and neck. It rarely affects the face.it may require oral and topical medication ,do contact for further Thank you