Hello,
The symptoms are suggestive of pityriasis alba. Pityriasis alba is a common hypopigmented dermatitis.This is a self-limited disorder that usually resolves by adulthood. Severe cases may benefit by Psoralen plus ultraviolet light A photochemotherapy (PUVA).
I sincerely advise you to consult a dermatologist and get it ruled out. It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
My son also had some light patches come up on him not too long ago. The doctor said it was just a rash caused by a virus and that it is nothing to be concerned about. He had it for over a month. Does your son itch at it and what nationality is your child? My doc at first thought he had pitarious rosea which is common in african americans. I was shocked since my son is caucasion so I asked for second opinion. Thats when he said it looks like all the other rashes that he sees after kids get a cold or the flu or allergies. HTH!