Vitiligo is a skin form characterized by the appearance of white patches on the skin. These patches appear particularly at a young age and are characterized by the alteration of melanocytes. In fact, cells capable of producing altered melanin cause hypochromic or achromic spots. In this article, you will be provided with useful information regarding Vitiligo.
Incidence of vitiligo on the population
In the white population, vitiligo is present, on average, in 1% of the population. But values approaching 5% have been reported in particular ethnic groups.
Vitiligo affected both sexes fairly evenly. However, it is women who make more use of specialist care.
There is no preferential predisposition regarding the color of the skin or hair in those affected by it. But we can speak of hereditary incidence for 20-40% of cases.
Vitiligo hardly manifests itself at birth. For this reason it can be defined as acquired. In some cases, however, it is possible that it manifests itself from the first days of life.
As regards the average age of patients, this leukoderma usually affects subjects between 10 and 30 years of age. There is also a maximum percentage of 50% that begins to show symptoms around the age of 20.
Heredity and Vitiligo
Further useful information regarding Vitiligo considers the relationship between disease and heredity.
The possibility of hereditary transmission of this particular dermatosis must be considered. In fact it has been found, for example, in monozygotic twins.
Vitiligo would proceed according to a mechanism of an autosomidominant nature, with variable and incomplete penetrance expressivity. In fact, the existence of a genetic marker is not demonstrable. In addition, other hereditary factors can be both the ABO blood group and the HLA histocompatibility antigen.
Research shows that physical or mental trauma may be possible causes of Vitiligo. This can also happen over a long period of time.
Sometimes it can be highlighted the existence of a positive Kobner in affected subjects. For this reason it is possible to hypothesize a predisposition to Vitiligo.
In most people with Vitiligo the number of patches can vary. They present themselves with a milky white color, more evident towards the peripheries (trichromovitiligo). While the edges appear hyperpigmented, especially in the phases of resolution of the pathology.
Sometimes the spot can feel itchy. This is due to the association of an inflammatory component with intradermal lymphocytic infiltrants.
The topographical body distribution of vitiligo spots is subject to extreme individual variability. However, in a good percentage of cases, it exists in the most affected skin areas. These areas are, for example, the extensor region of the elbows and knees, the dorsal surface of the fingers, the labial commissure and the periorificial tracts, in particular the genital ones.
The direct examination of the spots with the “Wood’s light” is of great use in their precise identification. It also highlights the true extent of the patches.
The scalp may also be affected by dermatosis (leukotrichia), with patchy or diffuse discoloration manifestations. Vitiligo on the scalp has an average incidence of 10% to 40%.
The evolution of the leukodermic patch can be rapid or slow, sometimes with an oscillating trend. In fact, periods of enlargement may alternate with others of shrinkage.
Finally, crises of spontaneous remission of hypochromia can also be observed, which always show the periollicular areas as the starting point. However, these are very rare occurrences.
When it comes to Vitiligo, the first important fact is the absence of melanocytes in the basal layer of the epidermis. They are in fact replaced with Langerhans cells or with cells of indeterminate nature.
This histological data, for example, is of great use in the differential diagnosis with a form of albinism, a disease in which, in the tyrosinase-negative variety, the melanocytes themselves are present, but with melanosomes blocked in the II evolutionary stage.
While in the tyrosinase-positive variety there seems to be a defect in the process of transfer of melanosomes to keratinocytes. In guttate hypomelanosis, a disease that appears only after the age of 50, melanocytes are present, but they function little or nothing.
Piebaldism also shows the same histological picture, but it is a disease that is already present at the time of birth.
Pathogenesis of Vitiligo
There are many pathogenetic hypotheses advanced for the interpretation of the causes of vitiligo.
Let us recall the most significant hypotheses:
- Of self-destruction
Therapy and Vitiligo
Last of the useful information on Vitiligo is about therapy.
In the past, several therapeutic attempts have been made to combat Vitiligo. However, no cure for vitiligo has been successful. Sometimes temporary results have been obtained. Examples of this type are the administration of furocoumarins and local corticotherapy.
To date, the suggestion that the dermatologist can propose to their vitiligo patients is to undergo a phototherapy treatment with ultraviolet rays. The results will not be evident from the first session, but they require patience and perseverance.
It was therefore learned that the only therapy currently possible for vitiligo is ultraviolet therapy with UVB rays.