In this condition, white patches appear on the skin in any body part. Scientifically it occurs when the cells melanocytes that produce a pigment called melanin (that gives color to your skin) stop producing enough melanin, which causes white patches on various parts of the skin or premature hair whitening. Emotional state, negative thoughts, lifestyle, anxiety, stress, or traumatic events can trigger Vitiligo. 

And it continues to spread until treated from a psychological perspective. There is no such cure for Vitiligo, but a skin specialist can help to improve the external appearance of your skin tone.