Vitiligo

Vitiligo is an acquired depigmenting disorder in which pigment cells (melanocytes) are destroyed, resulting in irregularly shaped white patches on the skin. Any part of the body may be affected. Common sites are exposed areas (face, neck, eyes, nostrils, nipples, navel, genitalia), body folds (armpits, groin), sites of injury (cuts, scrapes, burns) and around pigmented moles (halo naevi). The hair may also go grey early on the scalp, eyebrows, eyelashes and body. White hair is called ‘leukotrichia’. Leukotrichia is more likely in segmental vitiligo. The retina may also be affected.

Vitiligo

Mucosal vitiligo	Trichrome vitiligo	Poliosis

Who is prone to vitiligo?

Vitiligo affects 0.5-1% of the population, and occurs in all races. In half of sufferers, pigment loss begins before the age of 20. In one fifth, other family members also have vitiligo. Males and females are equally affected.

Even though most people with vitiligo are in good general health, some of them face a greater risk of having autoimmune diseases such as diabetes, thyroid disease, pernicious anaemia (B12 deficiency), Addison's Disease (adrenal gland disease) and alopecia areata (round patches of hair loss).

Classification of vitiligo

Classifications have identified clinical, genetic, pathobiological, epidemiological, and molecular characteristics of vitiligo.

The Vitiligo European Taskforce came to a consensus about classification of vitiligo in 2007.

• Nonsegmental vitiligo: focal, mucosal, acrofacial, generalised and universal subtypes
• Segmental vitiligo: focal, mucosal, unisegmental, bi- or multisegmental subtypes
• Mixed vitiligo (nonsegmental combined with segmental vitiligo)
• Unclassified vitiligo (early disease): focal at onset, multifocal asymmetrical non-segmental, mucosal (one site) subtypes

Nonsegmental vitiligo tends to be bilateral and symmetrical in distribution. If expanding areas or new areas of depigmentation occur, it is considered unstable. Vitiligo may also regress (improve). Vitiligo is considered stable if there is no progression or regression over a period of one to two years.

Segmental vitiligo occurs as a single white patch in 90%, but in a few, a second or rarely a third segment is affected. Each segment affects one side of the body. It arises in a young person and after the first year, generally remains stable. It is an example of cutaneous mosaicism. The segments often follow Blaschko lines, but occasionally have dermatomal pattern, phylloid pattern or checkerboard pattern. The border of the white patch can be irregular or less often, smooth. Leukotrichia may occur.

Mixed vitiligo is rare.

What is the cause of vitiligo?

Melanin is the pigment that determines the colour of skin, hair, and eyes. It is produced in cells called melanocytes. If melanocytes cannot form melanin or if their number decreases, skin colour will become progressively lighter.

The cause of vitiligo is not known but it is thought to be a systemic autoimmune disorder, although this has been disputed for segmantal vitiligo. There is a genetic susceptibility. New-onset vitiligo sometimes follows physical injury to the skin, such as sunburn, or emotional stress.

There are three theories on the cause of vitiligo:

• The pigment cells are injured by abnormally functioning nerve cells.
• There may be an autoimmune reaction against the pigment cells (the body may destroy its own tissue, which it perceives as foreign).
• Autotoxic theory – the pigment cells are self-destructive.

The severity of vitiligo differs with each individual. Light skinned people usually notice the pigment loss during the summer as the contrast between the affected skin and sun tanned skin becomes more distinct. People with dark skin may observe the onset of vitiligo any time. In a severe case pigment may be lost from the entire body. The eyes do not change colour. There is no way to predict how much pigment an individual will lose.

The degree of pigment loss can vary within each vitiligo patch which means that there may be different shades of brown in a vitiligo patch. This is called ‘trichrome’. A border of darker skin may circle an area of light skin.

Vitiligo frequently begins with a rapid loss of pigment which may be followed by a lengthy period when the skin colour does not change. Later, the pigment loss may begin again. The loss of colour may continue until, for unknown reasons, the process stops. Cycles of pigment loss followed by periods of stability may continue indefinitely.

Other causes of white skin should be excluded (leukoderma) including scars arising from severe trauma, burns, and deep skin infections.

What tests should be done?

Vitiligo is normally a clinical diagnosis, and no tests are usually necessary to make the diagnosis. The white patches may be seen more easily under Wood's light examination.

Occasionally biopsy may be recommended, particularly in early vitiligo, when a lymphocytic infiltration may be observed.

Blood tests to assess other potential autoimmune diseases may be arranged, such as thyroid function and autoantibody screen.

Clinical photographs are useful to document the extent of vitiligo for monitoring. Serial digital images may be arranged on follow-up. The extent of vitiligo may be scored according to the body surface area affected by depigmentation.

Protection against injury

Those prone to vitiligo should be careful to minimise skin injury as it is common for healing to result in a new white patch at the site (koebnerisation or isomorphic response). The injury might be a cut, a graze, an area prone to rubbing and depigmentation often develops with a linear shape. It has been reported to arise where jewellery or clothing items irritate the skin.

Protection against sun exposure

The white skin needs sun protection because it can only burn, it cannot tan. The normal skin also needs protecting to prevent sunburn (which could cause spreading of the vitiligo), and to reduce the contrast between the normal and the white skin.

• Wear protective clothing.
• Stay out of the sun at peak periods.
• Apply sunscreen (Sun Protection Factor 30+).

Sunburn in vitiligo

Images supplied by Dr Shahbaz A. Janjua

Use of cosmetics

• Carefully applied cosmetics can effectively disguise the vitiligo (cosmetic camouflage). Dyes, stains and make-ups can be applied and with specialist help the results can be very satisfactory. Some concealers are water-resistant.
• Dihydroxyacetone-containing "tan without sun" products; take care not to apply to the normally tanned skin because this will also look darker.
• Micropigmentation or tattooing may be considered if the vitiligo is stable.

Treatment of vitiligo

Treatment of vitiligo is currently not very satisfactory. Best results are obtained in vitiligo that is recent in onset and when it affects face and trunk. Repigmentation occurs from surviving pigment cells, mainly found in the hair follicle, or from melanocyte stem cells.

• Topical steroid cream. A potent anti-inflammatory cortisone cream may reverse the process if applied to the affected areas for a few weeks in their early stages while an inflammatory process is present.
• Calcineurin inhibitors such as topical pimecrolimus and tacrolimus have recently been shown to be safe and effective, and is especially useful on the face and neck where strong steroid creams may cause skin thinning.
• Narrowband UVB phototherapy is helpful in many patients, particularly in combination with calcineurin inhibitors, and perhaps with calcipotriol cream (usually used in psoriasis). Targeted phototherapy may be available to treat small areas of vitiligo.
• Excimer laser UVB has been reported to be effective.
• PUVA. This form of light treatment requires the patient to take a psoralen medicine orally, or apply a psoralen cream/paint to affected areas, prior to exposure to longwave ultraviolet light (UVA) for a few minutes. Hands and feet respond poorly, face and trunk do better. PUVA is usually prescribed twice weekly, and is continued for up to two years. PUVA is unsuitable for children or very fair skinned people.
• In some countries, psoralen is followed by sunlight exposure, but this is uncontrolled and overexposure to the sun can result in serious sunburn.

Surgical treatment of stable vitiligo.

Experimentally some centres are using surgical techniques to treat stable vitiligo and segmental vitiligo. Small sites can be treated using topical or local anaesthetic injections, but if large areas are treated, general anesthetic is necessary.

The top layer of vitiligo skin is removed by various techniques (including shaving, dermabrasion, sandpapering or laser) and replaced by pigmented skin removed from another site.

In non-cultured melanocyte-keratinocyte cell transplantion, the donor epidermis is separated from the dermis. Epidermal pieces are made into a cell suspension. The suspension is applied to the wounded vitiligo site and covered with a dressing. This method can be used on any site and large areas can be treated. However pain and risk of infection becomes greater when areas more than 250 sq cm are treated.

In punch grafting, tiny punches of normal skin are taken from a pigmented donor site and placed into the vitiligo skin. Cosmetic results are not as good as with cell transplantation, because scarring and cobblestone appearance may occur.

Blister grafts result in good cosmetic results and there is no scarring of the donor site. Blisters are formed by suction or cryotherapy. Blister grafting is time consuming, and the grafts are tricky to handle. It is therefore only suitable for small lesions.

Split skin grafting is quick to do, as the grafts can be applied directly onto dermabraded recipient area. It can lead to good results on small solitary patches of vitiligo.

Some researchers have used the patient's own melanocytes grown in tissue culture. This technique is restricted to research centers, and is expensive. Good results are reported, especially if the vitiligo affects a small area.

Adverse reactions to surgical treatments of vitiligo may include pain, wound infection hyperpigmentation, and post-treatment hypopigmentation (sometimes in a ring around the treated site).

Unfortunately, even when treatment has resulted in improvement, vitiligo may recur in treated and untreated sites.

Depigmentation therapy

If a dark skinned person has vitiligo affecting a large part of the exposed areas, he or she may wish to undergo depigmentation. A cream containing monobenzyl ether of hydroquinone, also called p-(benzyloxy)phenol, is applied to the skin. This can cause all the skin to lose its pigment. Its effect is usually permanent, but depigmentation may recur.