Vitiligo

Vitiligo is the patchy loss of skin pigmentation due to an auto-immune attack by the body's own immune system on skin melanocytes. It frequently begins in late adulthood with patches of unpigmented skin appearing on extremities. The patches may grow, or remain constant in size. Occasional small areas may repigment, as they are recolonised by melanocytes. Steroids have been used in treatment, but are not very effective.

The condition appears medically harmless, other than the problem that the affected skin areas have no protection against sunlight - they burn but never tan. However, if the skin is naturally dark, the visual effect of the white patches can be quite disfiguring. (If the affected person is of pale-skinned ancestry, the patches can be at least be rendered invisible by the expedient of avoiding sunlight and the tanning of unaffected skin)

It has been claimed that the singer Michael Jackson has his skin bleached to mask the effects of vitiligo.