Vitiligo is linked to the depigmentation of certain areas of the skin. Apart from the hands or feet, the areas around the facial openings are the most affected: around the mouth, nose, eyes or ears.
In fact, it is the melanocytes that "fall asleep". We do not know why. Melanocytes are the cells that allow pigmentation of the skin and hair.
Suddenly, often before the age of 20, these melanocytes no longer produce melanin. It is the concentration of melanin that determines the color of the skin. If the melanocytes no longer produce melanin, the skin and hair become white.
Sometimes the pigmentation restarts. This can happen: pigmentation resumes, melanocytes wake up. This can happen as a result of treatment or spontaneously.
Again, we do not know why. And, when the pigmentation restarts, it is, most of the time, at the level of a hair! Why ? Because, under the hair, at the level of the pore of the skin, at the bottom, is a sheath. In this sheath pilaris, sometimes, are still some melanocytes.
The pigment can then go up. We observe at the level of the hair, and in the middle of a depigmented area (white), a small dark spot which is reformed. Like an island of repigmentation in the middle of a white plate.