Vitiligo
Le vitiligo is a skin condition characterized by the appearance of white spots on the feet, hands, face, lips or any other part of the body. These spots are caused by “depigmentation”, that is to say the disappearance of melanocytes, the cells responsible for the color of the skin (Brightness and ).
The depigmentation can be more or less important, and the white spots, of variable sizes. In some cases, the hair or hair that grows inside the depigmented areas is also white. Vitiligo is neither contagious nor painful, but it can cause significant psychological distress.
Le vitiligo is a disease whose symptoms are especially troublesome from an aesthetic point of view, the spots being neither painful nor directly dangerous for health. As a result, vitiligo is often “minimized” and is still insufficiently managed by doctors. However, it is a disease that has a very negative impact on the quality of life of those affected, as confirmed by a study conducted in 2009.20. Especially people with dark skin suffer from it. |
Prevalence
Le vitiligo affects approximately 1% to 2% of the population. It usually appears around the age of 10 to 30 years (half of those affected are before the age of 20). Vitiligo is therefore quite rare in children. It affects both men and women, and occurs all over the world, on all skin types.
Types of vitiligo
There are several types of vitiligo21 :
- le vitiligo segmentaire, located on only one side of the body, for example on part of the face, upper body, leg or arm. This form of vitiligo appears more often in children or adolescents. The depigmented area corresponds to an “innervation territory”, that is to say an area of the skin innervated by a particular nerve. This form appears rapidly in a few months, then generally ceases to evolve;
- le generalized vitiligo which appears in the form of spots that are often more or less symmetrical, affecting both sides of the body, in particular areas of repeated friction or pressure. The term “generalized” does not necessarily mean that the spots are extensive. The course is unpredictable, the spots being able to remain small and localized or to spread quickly;
- le vitiligo universalis, rarer, which spreads quickly and can affect almost the entire body.
Causes
The causes of vitiligo are not well known. However, we know that the appearance of white spots is due to the destruction of melanocytes, these skin cells that produce melanin. Once the melanocytes are destroyed, the skin turns completely white. Several hypotheses are now advanced to explain the destruction of melanocytes23. Vitiligo is probably a disease that has both genetic, environmental and autoimmune origins.
- Autoimmune hypothesis
Vitiligo is a disease with a strong autoimmune component. This is because people with vitiligo produce abnormal antibodies that directly attack melanocytes and help destroy them. In addition, vitiligo is often associated with other autoimmune diseases, such as thyroid disorders, which suggests the existence of common mechanisms.
- Genetic hypothesis
Vitiligo is also linked to genetic factors, not all of which have been clearly identified22. It is common for several people to have vitiligo in the same family. At least 10 genes are involved, as a study showed in 201024. These genes play a role in the immune response.
- Accumulation of free radicals
According to several studies23, the melanocytes of people with vitiligo accumulate many free radicals, which are forms of waste produced naturally by the body. This abnormal accumulation would lead to a “self-destruction” of the melanocytes.
- Nerve hypothesis
Segmental vitiligo results in depigmentation of a delimited area, corresponding to the area innervated by a given nerve. For this reason, researchers thought that depigmentation could be linked to the release of chemical compounds from the ends of the nerves, which would decrease the production of melanin.
- Environmental factors
Although they are not the cause of vitiligo itself, several triggering factors can contribute to the appearance of spots (see risk factors).
Melanocytes and melanin Melanin (from the Greek melanos = black) is a dark pigment (of the skin) produced by melanocytes; it is responsible for the color of the skin. It is mainly genetics (but also exposure to the sun) that dictates the amount of melanin contained in the skin. Albinism is also a pigmentation disorder. Unlike vitiligo, it is present from birth and results in a general absence of melanin in the skin, body hair, hair and eyes.
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Evolution and complications
Most often, the disease progresses to a unpredictable rhythm and can stop or expand without knowing why. Vitiligo can progress in phases, with aggravations sometimes occurring after a psychological or physical triggering event. In rare cases, the plaques go away on their own.
Apart from cosmetic damage, vitiligo is not a serious disease. People with vitiligo, however, have an increased risk of developing skin cancer because the depigmented areas no longer form a barrier to the sun’s rays. These people are also more likely to suffer from other autoimmune diseases. However, this is not the case for people with segmental vitiligo.