What does a white patch on the skin mean?

Condition analysis:
Hello, according to the situation, it should be consider the symptoms of vitiligo. Patients with vitiligo will notice expanding white patches on their skin. This is due to the loss of melanin; which is the pigment that gives the skin, hair and eyes their color. There is no cure for vitiligo, although certain treatments may be helpful in slowing or stopping the condition's progression.

Instructions:
Diet restriction has much important role in Vitiligo & Leucoderma. Vitiligo & Leucoderma treatment also require food restriction for proper healing of patches. The diet restrictions mentioned below also helps in control of spread in Vitiligo.

1) Diet related 
Curd, Tamarind, Raw Tomato, Raw Onion, Raw garlic, Brinjal, Papaya, Green chili, Pickles, Citrus fruits & Citrus fruit items / juices as oranges, lemon even grapes are strictly restricted. Fish and red meat should also be restricted. Oily / spicy food & non vegetarian food intake should be lowered. Milk & milk product intake to be lowered (not in case of kids). One should not take medicines containing Amla (Gooseberry - a rich source of Vit. C). . . Any eatable made of soda bi carb, stored sour things, junk food, tinned foods or drinks, chocolates, coffee or cocoa products should not be taken regularly.

2) Lifestyle related 
Tight fittings, which give marks on the skin, like elastic must be avoided which disturbs the skin blood circulation. Scratching, itching must be avoided. Any injury will give rise to new patch. Plastic and rubber wear should be avoided. Plastic Ornaments, Bindi or any Stickers on the skin should be avoided. Avoid playing or swimming in the sun between 11 a.m. to 4 p.m.