What causes white patches on the skin?

White Patches. Psoriasis and vitiligo, may cause a light or white patch or other discoloration on skin. Treatment focuses on controlling the length and severity of flare-ups. See your doctor to make sure of the diagnosis.
Couple possibilities. Fun in the sun often brings out these white spots -- especially noticeable at the end of the summer. While a healthy, balanced diet of whole foods is very beneficial, diet is probably not responsible. Many different conditions can produce new white patches in children, the two most common are pityriasis alba and tinea versicolor.