This is hypopigmentation - loss of pigment after a laser or light treatment. I'm sorry this is too hard to answer without a photo though specifically. And are you saying you had no problems with treatments? Were you ever burned? What kind of machine was used to treat you? How many treatments did you have? Depending on the type of machine used and other variables, some pigment lightening around the intended area can occur, especially with IPL, and this is called hypopigmentation.