Loss of pigment in the skin has serious cosmetic implications, especially when occurring on the face, and pre-disposes that area of skin to severe sun burn.
Depigmentation can have genetic causes on rare occasions. It can result from trauma to the skin and occasionally infections. More commonly it arises from an autoimmune process called vitiligo where the pigment cells are destroyed leaving white patches.
Early diagnosis and treatment of this is important to try and prevent worsening pigment loss and hopefully get re-pigmentation.