Dr. Please say what is these marks. Why it happens?

A. Nutritional deficiencies Deficiencies in calcium, vitamin D and vitamin E can cause white patches on the skin.Sometimes a small area of skin becomes irritated, which results in a patch of skin that's lighter in pigment than is the skin around it (pityriasis alba). This is common in children who have eczema.Deficiencies in calcium, vitamin D and vitamin E can cause white patches on the skin. While harmless, these white spots indicate that you need to eat a healthy, balanced diet.