What Causes White Patches on the Skin?

Vitiligo, pronounced vit-uh-LIE- go, is condition in which the skin turns white due to the loss of melanocytes. These cells produce melanin, the pigment that gives the skin its characteristic color. (Melanocytes also impart color to the retina of the eye and the mucous membrane tissues lining the inside of the mouth, nose, genital and rectal areas). In vitiligo, the melanocytes are mysteriously destroyed, leaving depigmented patches of skin on different parts of the body. The hair that grows in areas affected by vitiligo may also turn white.

Vitiligo is a common disorder. It occurs in 1-2% of people and affects both sexes and all races equally. Vitiligo is never present at birth. It crops up between the ages of 10 and 30 in about half of cases and before age 40 in 95% of cases. More than 30% of people with vitiligo have a family history of the disorder, pointing to the presence of genetic factors capable of contributing to the condition.

As the skin gradually loses it's color, patch by patch, other people may treat someone with vitiligo like a leper, thinking they have a contagious skin disease. In fact, vitiligo is called "white leprosy" in India. Women with it are often discriminated against in marriage. If they develop vitiligo after marriage, it can be grounds for divorce.

In people with vitiligo, the melanocytes self-destruct, probably because of an autoimmune reaction in which the body mistakenly attacks its own cells. The resulting white patches of skin may enlarge and increase in number for a while, and then the condition may stabilize, only to start up again later. Injury, illness, a bad sunburn and severe stress have been known to provoke the onset or progression of vitiligo.

Vitiligo is sometimes associated with more serious disorders that also have an autoimmune cause, including: hyperthyroidism (overactivity of the thyroid gland), adrenocortical insufficiency (the adrenal gland does not produce enough cortisol), alopecia areata (patches of baldness), and pernicious anemia (a low level of red blood cells caused by the failure of the body to absorb vitamin B12). Vitiligo is also a feature of a number of genetic diseases.

People with vitiligo must protect their skin from exposure to the sun. Affected areas of skin can become seriously sunburned while the surrounding skin tans. Affected people must be vigilant about using sunscreen with a high sun protection factor (an SPF of 30 or above) on exposed skin. During long periods outdoors, they should wear long sleeves, pants and wide-brimmed hats.

If the affected area is small, application of creams containing corticosteroids may help restore pigment. Chronic use of steroids, however, can result in thinning of the skin and stretch marks in some areas.

Dermatologists use a remedy called PUVA for those seeking to darken white skin patches, especially when the condition is extensive. PUVA involves taking a drug called psoralen, which makes the skin very sensitive to light, followed by exposure of the affected skin to a special lamp that generates only ultraviolet A radiation. Occasionally, when the vitiligo patches are very limited, psoralen can be applied directly to the skin before ultraviolet A treatment.

The downside of PUVA therapy is that it is time-consuming and care must be taken to avoid side effects, which can sometimes be severe. At least a year of twice-weekly treatments is usually needed to restore melanin production. The treatments are 50 to 70% successful in restoring color on the face, trunk and upper arms and legs. But hands and feet respond poorly to this approach. PUVA should not be used in children under 12, in pregnant or nursing women, or in people with certain medical conditions. Long-term use of PUVA can cause freckling and, when used for years to treat psoriasis, PUVA increases the risk of skin cancer. Risks aside, the most effective treatment available now is PUVA. The goal of PUVA therapy in vitiligo is to reverse the effects of the disease and repigment the white patches.