Vitiligo

Vitiligo[p] is a relatively common chronic disorder that causes depigmentation in patches of skin. It occurs when the melanocytes, the cells responsible for skin pigmentation which are derived from the neural crest, die or are unable to function. The precise pathogenesis, or cause, of vitiligo is complex and not yet fully understood. There is some evidence suggesting it is caused by a combination of autoimmune, genetic, and environmental factors. It is also common in people with thyroid disorders. The population incidence worldwide is considered to be between 1% and 2%.[citation needed] Non-segmental vitiligo has a greater prevalence than the disorder's other form(s).
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Signs and symptoms

The most notable symptom of vitiligo is depigmentation of patches of skin that occurs on the extremities. Although patches are initially small in size, they can often start to enlarge and change shape. When skin lesions occur, they are most prominent on the face, hands and wrists. Depigmentation is particularly noticeable around body orifices, such as the mouth, eyes, nostrils, genitalia and umbilicus. Some lesions have a tendency to hyperpigment around the edges. In a more general sense, vitiligo is similar in appearance to leprosy, and as such (in countries where leprosy is prevalent), individuals with vitiligo can be stigmatized for the similarities in appearance.In regards to psychological damage, vitiligo can have a significant effect on the mental health of a patient. Psychological stress may even result in an individual becoming more susceptible to vitiligo. Patients who are stigmatised for their condition may experience depression and similar mood disorders.

Non-segmental vitiligo

In non-segmental vitiligo (NSV), there is usually some form of symmetry in regards to the location of the patches of depigmentation. New patches also appear over time, and can be generalised over large portions of the body, or localised 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.

Segmental vitiligo

Segmental vitiligo (SV) differs in appearance, aetiology and prevalence of associated illnesses. Its treatment is also different to that of NSV. It tends to affect areas of skin that are associated with dorsal roots from the spine. It spreads much more rapidly than NSV and, without treatment, patches of depigmented skin remain throughout life.

Pathogenesis

Vitiligo is associated with autoimmune and inflammatory diseases, commonly thyroid overexpression and underexpression. A study comparing 656 people with and without vitiligo in 114 families found several mutations (single-nucleotide polymorphisms) in the NALP1 gene.The NALP1 gene, which is on chromosome 17 located at 17p13, is on a cascade that regulates inflammation and cell death, including myeloid and lymphoid cells, which are white cells that are part of the immune response. NALP1 is expressed at high levels in T cells and Langerhan cells, white blood cells that are involved in skin autoimmunity.

Treatment

There are a number of ways to alter the appearance of vitiligo without addressing its underlying cause. 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 sunlight and the sun tanning of unaffected skin. However, exposure to sunlight may also cause the melanocytes to regenerate to allow the pigmentation to come back to its original color.

The traditional treatment (if any) given by most dermatologists is corticosteroid cream.

Phototherapy may also be beneficial. Using exposure to long-wave ultraviolet (UVA) light from the sun or from UVA, together with Psoralen, called "PUVA", or with UVB Narrowband lamps (without Psoralen), can help in many cases.

Alternatively, some people with vitiligo opt for chemical depigmentation, which uses 20% monobenzone (monobenzylether of hydroquinone). This process is irreversible and generally ends up with complete or mostly complete depigmentation.