Non-segmental vitiligo of the hand.
|Classification and external resources|
Vitiligo is a chronic skin condition characterized by portions of the skin losing their pigment. It occurs when skin pigment cells die or are unable to function. Aside from cases of contact with certain chemicals, the cause of vitiligo is unknown. Research suggests vitiligo may arise from autoimmune, genetic, oxidative stress, neural, or viral causes. Vitiligo is typically classified into two main categories: segmental and non-segmental vitiligo. Half of those affected show the disorder before age 20, though most develop it before age 40.
The global incidence of vitiligo is less than 1%, with some populations averaging 2–3% and rarely as high as 16%. Autoimmune diseases such as Addison's disease, Hashimoto's thyroiditis, and type 1 diabetes mellitus tend to occur more often in people who have vitiligo. There is no known cure for vitiligo but many treatment options are available including topical steroids, calcineurin inhibitors, and phototherapy.
Classification attempts to quantify vitiligo have been analyzed as being somewhat inconsistent, while recent consensus have agreed to a system of segmental vitiligo (SV) and non-segmental vitiligo (NSV). NSV is the most common type of vitiligo.
In non-segmental vitiligo (NSV), there is usually some form of symmetry in the location of the patches of depigmentation. New patches also appear over time and can be generalized over large portions of the body or localized to a particular area. Vitiligo where little pigmented skin remains is referred to as vitiligo universalis. NSV can come about at any age (unlike segmental vitiligo, which is far more prevalent in teenage years).
Classes of non-segmental vitiligo include the following:
Segmental vitiligo (SV) differs in appearance, cause and prevalence from associated illnesses. Its treatment is different from that of NSV. It tends to affect areas of skin that are associated with dorsal roots from the spinal cord and is most often unilateral. It spreads much more rapidly than NSV and, without treatment, it is much more stable/static in course and its association with autoimmune diseases appears to be weaker than that of generalized vitiligo. SV is a very treatable condition that responds to topical treatment.
The only sign of vitiligo is the presence of pale patchy areas of depigmented skin which tend to occur on the extremities. The patches are initially small, but often grow and change shape. When skin lesions occur, they are most prominent on the face, hands and wrists. The loss of skin pigmentation is particularly noticeable around body orifices, such as the mouth, eyes, nostrils, genitalia and umbilicus. Some lesions have increased skin pigment around the edges. Patients who are stigmatized for their condition may experience depression and similar mood disorders.
Although multiple hypotheses have been suggested as potential triggers that cause vitiligo, studies strongly imply that changes in the immune system are responsible for the condition. Vitiligo has been proposed to be a multifactorial disease with genetic susceptibility and environmental factors both thought to play a role.
The TYR gene encodes the protein tyrosinase, which is not a component of the immune system, but is an enzyme of the melanocyte that catalyzes melanin biosynthesis, and a major autoantigen in generalized vitiligo. Some state the sunburns can cause the disease but there is not good evidence to support this.
Variations in genes that are part of the immune system or part of melanocytes have both been associated with vitiligo. It is also thought to be caused by the immune system attacking and destroying the melanocytes of the skin. A genomewide association study found approximately 36 independent susceptibility loci for generalized vitiligo.
Vitiligo is sometimes associated with autoimmune and inflammatory diseases such as Hashimoto's thyroiditis, scleroderma, rheumatoid arthritis, type 1 diabetes mellitus, psoriasis, Addison's disease, pernicious anemia, alopecia areata, and systemic lupus erythematosus.
Among the inflammatory products of NALP1 are caspase 1 and caspase 7, which activate the inflammatory cytokine interleukin-1β. Interleukin-1β is expressed at high levels in patients with vitiligo. In one of the mutations, the amino acid leucine in the NALP1 protein was replaced by histidine (Leu155->His). The original protein and sequence is highly conserved in evolution, and is found in humans, chimpanzee, rhesus monkey, and the bush baby. Addison's disease (typically an autoimmune destruction of the adrenal glands) may also be seen in individuals with vitiligo.
An ultraviolet light can be used in the early phase of this disease for identification and to determine effectiveness of treatment. Skin with vitiligo, when exposed to a blacklight, will glow blue. In contrast, healthy skin will have no reaction.
Conditions with similar symptoms include the following:
There is no cure for vitiligo but several treatment options are available. The best evidence is for applied steroids and the combination of ultraviolet light in combination with creams. Due to the higher risks of skin cancer, the United Kingdom's National Health Service suggests phototherapy only be used if primary treatments are ineffective. Lesions located on the hands, feet, and joints are the most difficult to repigment; those on the face are easiest to return to the natural skin color.
Topical preparations of immune suppressing medications including glucocorticoids (such as 0.05% clobetasol or 0.10% betamethasone) and calcineurin inhibitors (such as tacrolimus or pimecrolimus) are considered to be first-line vitiligo treatments.
Phototherapy is considered a second-line treatment for vitiligo. Exposing the skin to light from UVB lamps is the most common treatment for vitiligo. The treatments can be done at home with an UVB lamp or in a clinic. The exposure time is managed so that the skin doesn't suffer overexposure. Treatment can take a few weeks if the spots are on the neck and face and if they existed not more than 3 years. If the spots are on the hands and legs and have been there more than 3 years, it can take a few months. Phototherapy sessions are done 2–3 times a week. Spots on a large area of the body may require full body treatment in a clinic or hospital. UVB broadband and narrowband lamps can be used, but narrowband ultraviolet picked around 311 nm is the choice. It has been constitutively reported that combination of UVB phototherapy with other topical treatments improves repigmentation.
Ultraviolet light (UVA) treatments are normally carried out in a hospital clinic. Psoralen and ultraviolet A light (PUVA) treatment involves taking a drug that increases the skin's sensitivity to ultraviolet light, then exposing the skin to high doses of UVA light. Treatment is required twice a week for 6–12 months or longer. Because of the high doses of UVA and psoralen, PUVA may cause side effects such as sunburn-type reactions or skin freckling.
Narrowband ultraviolet B (NBUVB) phototherapy lacks the side-effects caused by psoralens and is as effective as PUVA. As with PUVA, treatment is carried out twice weekly in a clinic or every day at home, and there is no need to use psoralen.
In mild cases, vitiligo patches can be hidden with makeup or other cosmetic camouflage solutions. If the affected person is pale-skinned, the patches can be made less visible by avoiding tanning of unaffected skin.
Most vitiligo is idiopathic; however, in cases where it is triggered by skin bleaching or other substances, it is said to be chemical after being treated with bleaching agents. In cases of extensive vitiligo the option to de-pigment the unaffected skin with topical drugs like monobenzone, mequinol, or hydroquinone may be considered to render the skin an even colour. The removal of all the skin pigment with monobenzone is permanent and vigorous. Sun-safety must be adhered to for life to avoid severe sun burn and melanomas. Depigmentation takes about a year to complete.
Descriptions of a disease believed to be vitiligo date back to a passage in the medical text Ebers Papyrus circa 1500 BC in ancient Egypt. Mentions of whitening of the skin was also present circa 1400 BC in sacred Indian texts such as Atharvaveda as well as Shinto prayers in East Asia circa 1200 BC. The Hebrew word "Zora'at" from the Old Testament book of Leviticus dating to 1280 BCE (or 1312 BCE) described a group of skin disease associated with white spots, and a subsequent translation to Greek led to continued conflation of those with vitiligo with leprosy and spiritual uncleanliness. Medical sources in the ancient world such as Hippocrates often did not differentiate between vitiligo and leprosy, often grouping these diseases together. In Arabic literature, the word "alabras" has been associated with vitiligo, with this word found in the Koran. The name "vitiligo" was first used by the Roman physician Aulus Cornelius Celsus in his classic medical text De Medicina.
The etymology of the term "vitiligo" is believed to be derived from "vitium", meaning "defect" or "blemish".
In October 1992, a scientific report was published of successfully transplanting melanocytes to vitiligo affected areas, effectively repigmenting the region. The procedure involved taking a thin layer of pigmented skin from the patient's gluteal region. Melanocytes were then separated out to a cellular suspension that was expanded in culture. The area to be treated was then denuded with a dermabrader and the melanocytes graft applied. Between 70 and 85 percent of patients experienced nearly complete repigmentation of their skin. The longevity of the repigmentation differed from person to person. By now, a number of transplantation techniques has been developed, including transplantation of melanocyte precursors derived from hair follicles. Transplantation procedures are frequently used to treat segmental vitiligo which is poorly responsive to other types of treatment. In non-segmental vitiligo, success is achieved when treating patches that are not expanding (so called stable vitiligo).
The autopsy apparently confirmed what Jackson told people who questioned why his skin tone became lighter in the 1980s. Jackson had 'vitiligo, a skin pigmentation disease,' [LA coroner Dr. Christopher] Rogers said. 'So, some areas of the skin appear light and others appear dark.'
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