What is Vitiligo
Vitiligo (from the Latin vitulum, “white spot”) is a chronic acquired hypomelanotic dermatosis, which results in a lack (hypochromia) or a total lack (acromia) of pigment. This pathology, which affects 0.5-2% of the world’s population, manifests itself in the form of white patches with clear margins, often hyperpigmented, which highlight the contrast of color with the normally pigmented skin surrounding it. These patches are usually (but not always) symmetrically arranged and can appear in any part of the body; their onset is independent of factors such as sex, skin colour or hair colour of the affected subjects.
Vitiligo appears in 50% of cases before the age of twenty, often after significant psychoemotional events. It is a clinically asymptomatic disease, and for this reason too often unjustly considered a mere aesthetic problem, of minimal importance for health; in reality, in addition to often causing a significant decrease in the quality of life and self-esteem of the patient, vitiligo should be considered carefully also because it often occurs in association with other diseases of internal or dermatological interest. According to some estimates, 75% of those affected consider vitiligo disfiguring and intolerable; in general, therefore, this disease can be experienced in a rather dramatic way, causing psychoemotional reactions even very relevant, sometimes even affecting the way the patient interacts with the family and social context.
Even if vitiligo has been known for thousands of years (descriptions of it are already present in the famous Writings of Hebres, dating back to about 2500 BC), it is still possible to find a way to describe it.), its causes are still not entirely clear: the possibility of family transmission is suggested by the fact that a percentage of 20-40% of subjects with vitiligo has one or more relatives affected by this disease and for this reason the genetic factors are considered relevant; it is also known that the event triggering vitiligo is the death or functional inactivation of melanocytes, the cells responsible for the production of melanin.
Several hypotheses have been put forward on how this melanocytic destruction takes place, of which the most accredited are:
- the neural hypothesis, according to which “anomalous” nerve fibres cause the death of melanocytes in the skin areas they innervate;
- the autocytotoxic hypothesis, according to which defective melanocytes, or cells close to them, produce toxic substances for themselves that would cause their disappearance;
- the autoimmune hypothesis, according to which it is the immune system of the affected person to recognize the melanocytes as foreign bodies and to attack them causing their death.
In addition to these fundamental mechanisms, other elements under study would seem to contribute to the development of the disease: viral infections, abnormalities in the mechanisms of protection from free radical damage and, finally, altered response to growth factors.
Because of the possibility of association with numerous, specific clinical skin and extracutaneous conditions, it has been suggested to consider vitiligo no longer as a simple disease but as a syndrome: in some cases, in fact, it can be the epiphenomenon of organic diseases, among which other syndromes stand out for their frequency on an autoimmune basis.