Vitiligo is a long-term condition that causes pale, white patches to develop on the skin due to lack of a chemical called melanin. Vitiligo can affect any area of your skin, but most commonly occurs on skin exposed to the sun, such as your face, neck and hands. The condition varies from person to person. Some people only get a few small, white patches that progress no further. Other people get bigger white patches that join up across large areas of their skin. There is no way of predicting how much of your skin will be affected. The white patches are usually permanent.