Vitiligo is a disease that affects about 1% of the world population and causes progressive depigmentation of the skin, reaching all ethnicities, being, however, clinically more evident when it occurs in people with darker skin. In this text we will address the causes and current treatment options for vitiligo.
The causes of vitiligo are not yet clear. Genetic factors appear to be important, since 20 to 30% of patients with vitiligo have a positive family history of the disease. It is now believed that the disease has an autoimmune origin, with inappropriate production of antibodies and T lymphocytes (a type of white blood cell) against melanocytes*, the cells responsible for the production of pigment of the skin.
* Melanocytes are the cells that produce melanin, a pigment that gives color to our skin, protecting us from solar radiation. When we get sun we get darker skin due to increased melanin production stimulated by UV-A and UV-B rays. The darker the skin, the greater the protection from the harmful effects of solar radiation. Melanin is also responsible for the color of the hair and eyes. Afro-descendants have darker skin and hair because they produce a lot of melanin; Caucasians have lighter skin and hair as they produce less melanin. Albinos have very light skin and hair as they do not produce any melanin. When melanocytes mutate and turn into malignant cells, melanoma appears, one of the most aggressive types of skin cancer.
In addition to the production of autoantibodies against melanocytes, patients with vitiligo have a higher incidence of other autoimmune diseases such as:
However, it is important to note that some patients with vitiligo do not have a positive family history or other associated autoimmune diseases.
Regardless of the cause, the fact is that the disease arises due to the destruction of melanocytes. When a biopsy is performed on an affected area of the skin, it is possible to verify an absence of these cells responsible for the production of melanin, the skin's natural pigment.
Vitiligo can appear at any age, but its peak incidence occurs during the second and third decades of life.
Vitiligo vulgaris is the most common subtype and often causes diffuse depigmentation plaques on the body. The most affected sites include arms, hands, feet, knees, navel, lips and around the mouth, eye, nose and genitals.
The lesions of vitiligo are more apparent in people with darker skin and appear as clear patches on plaques, where it is very easy to delimit the healthy skin of the affected skin. The lesions are usually symmetrical by affecting the body bilaterally. In some cases, however, vitiligo may be restricted to only one half of the body.
Vitiligo may also cause depigmentation of mucous membranes such as gums and loss of hair and hair color.
Vitiligo is a progressive disease that presents new depigmentations over time. However, some cases do not evolve and up to 10% of the patients present spontaneous repigmentation of the lesions.
It is impossible to know in advance how vitiligo will evolve in each individual patient. The clinical picture is extremely unpredictable, ranging from a few small lesions restricted to a region to a universal vitiligo where more than 50% of the body is affected.
In patients with focal vitiligo, restricted to small areas of the body, or in those who already have very clear skin, the use of makeup to camouflage the lesions and the sunscreen to prevent tanning of healthy areas, avoiding the increase of contrast, are usually satisfactory solutions.
In patients with brown skin and disseminated lesions, especially on the face, treatment with repigmentation drugs is indicated. The sooner the treatment is started, the better; however, the response usually varies greatly from case to case.
The use of corticosteroid ointments is often the first choice for patients with depigmentation on less than 10% of body surface area. It takes at least three months of treatment to notice any result. Topical corticosteroids present as a side effect a possible atrophy of the skin, and the patient should be evaluated by a dermatologist every four weeks.
An option for corticosteroids is tacrolimus or topical pimecrolimus; however, a possible relationship between the use of these two drugs and an increased incidence of lymphoma is still under investigation.
Photochemotherapy with psoralen components (substances capable of increasing skin sensitivity to ultraviolet rays) and subsequent exposure to UV-A radiation is commonly referred to as "PUVA therapy". Currently there is also the option of using radiation with UV-B rays instead of UV-A rays, and there is no need to sensitize the skin with psoralens. This treatment is usually done two to three times a week for a period of 6 to 12 months. The best results occur in those with vitiligo in less than 20% of the body.
The use of laser therapy is another option, but it is expensive and can only be used in small areas.
Graft or transplantation of melanocytes is an option in patients who have stable disease for at least two years. This treatment works best in cases of vitiligo with unilateral involvement.
Total depigmentation with hydroquinone is the last alternative and is usually indicated in the most severe cases, with involvement of more than 50% of the body and lack of response to other treatments. Depigmentation is permanent and leaves the patient very vulnerable to the harmful effects of the sun's rays.
