Vitiligo: This total loss of skin pigment and affects 1 percent of the population. People may be at higher risk for this skin bleaching if they have thyroid disorders, pernicious anemia, decreased adrenal gland function or a condition called alopecia areata that causes hair loss. Possible causes include abnormal nerve cells that hinder the body’s production of pigment or an autoimmune or autotoxic reaction in which the pigment cells are attacked.

Treatment: When a high percentage of pigment has been lost, an oral medication can rid the body of the remaining pigmentation to achieve a uniform lighter look. For those with less pigment loss, a type of so-called ultraviolet therapy sometimes restores a significant amount of pigment to the white patches.