A disorder in which melanocytes, the cells that make pigment in the skin, the mucous membranes, and the retina of the eye, are destroyed, leading to the development of white patches on the skin. Studies have suggested that vitiligo may be more common in people with Type 1 diabetes.
Vitiligo is thought to develop in about 0.1% to 2% of various populations, affecting 2–5 million people in the United States and 40–50 million people worldwide. Like Type 1 diabetes, vitiligo appears to be an autoimmune disease, in which the body’s immune system launches a misguided attack on its own tissues. In the case of vitiligo, the target of the autoimmune attack is the melanocytes.
The first symptoms of vitiligo that people typically notice are white patches on the skin, most commonly in areas exposed to the sun. Vitiligo in itself is not physically damaging or life-threatening, but the cosmetic changes it triggers can affect people’s psychological well-being, interfere with their social and sexual interactions, and make it difficult for them to get and keep jobs.
Vitiligo can be extremely difficult to treat. Traditionally, medical therapies have included topical steroid creams that encourage repigmentation, “phototherapy” in combination with oral or topical administration of the drug psoralen, and depigmentation with drugs applied to the pigmented skin that fade it to match the white patches. None of these therapies has been ideal, but there have been significant advances in therapy in recent years.
For many years, a treatment called psoralen and ultraviolet A photochemotherapy (or PUVA) has been the “gold standard” of treatment for vitiligo. Psoralens are drugs that react with ultraviolet light to cause darkening of the skin. PUVA involves taking psoralen orally or applying it topically to the skin, then being exposed to ultraviolet A (UVA) light for a specified amount of time. Typically, psoralen is used topically when there are only a few patches of depigmentation (less than 20% of the total skin surface). A thin coat of psoralen is applied to the person’s patches about 30 minutes before exposure. The dose of UVA light exposure is gradually increased over a period of many weeks. The major side effects of topical PUVA are severe sunburn and too much repigmentation, or darkening, of the patches and surrounding skin.
Oral PUVA is reserved for people with more extensive vitiligo and those who don’t respond adequately to topical PUVA. A person takes psoralen orally about two hours before UVA light exposure. Oral psoralen has a number of potential side effects, including sunburn, nausea and vomiting, abnormal hair growth, and too much pigmentation; oral PUVA may also raise the risk of skin cancer.
In recent years, doctors have experimented with using narrowband ultraviolet B (UVB) light, which has a slightly shorter wavelength than UVA. Studies of the technique have shown that people treated with narrowband UVB have significantly enhanced repigmentation and fewer side effects compared with those treated with PUVA. Other studies have suggested that narrowband UVB may produce repigmentation comparable to what is achieved with oral PUVA treatment. Small studies have also explored the effects of a related type of therapy called targeted light therapy, sometimes using lasers, with some promising results.
Topically applied immunomodulatory drugs, or drugs that alter the immune system, also look promising. Tacrolimus, which inhibits the production of various body proteins that promote inflammation, has been shown in small clinical trials to achieve repigmentation with minimal side effects both on its own and in combination with laser therapy. A similar drug called pimecrolimus has also shown promise.