Vitiligo

This is a patchy loss of melanin from the epidermis causing areas of pale skin. Sometimes the loss is partial. There may also be loss of melanin in hair follicles. It is usually seen as an auto-immune disease and is associated with other such diseases.¹

Theories about aetiology include:

• Immune destruction
• Destruction of the melanocytes by a neurochemical
• Destruction of the melanocytes by a metabolic product of melanin
• A genetic predisposition

None of these theories is entirely satisfactory and the truth may be a mixture of all. Long after the onset of the disease the melanocytes are still present but inactive.¹

It occurs in about 1-2% of the population. Around 30% have clustering in families. It is more obvious but no more frequent in dark skinned races. Sex distribution is equal.^2,3

Risk factors

As well as familial clustering there is an association with auto-immune thyroid disease and other auto-immune conditions including pernicious anaemia.⁴ The presence of thyroid antibodies may well precede or follow the onset of vitiligo, especially in children, and anyone with the disease should receive regular screening, repeated if necessary.⁵There is also an association with certain HLA antigens in various groups. The HLA-B13 is related to thyroid disease and vitiligo.The disease can occur after trauma or injury or in response to occupational exposure to some chemicals.⁶

The condition can present at any age but most commonly is noticed around the age of 20.

In early disease the white areas are indistinct and there may be pruritis.³

• The patches of vitiligo tend to be clearly circumscribed areas of whiteness. They are especially obvious if the surrounding skin is dark. As they will not tan in sunlight they become more apparent after exposure. Furthermore, because of the loss of melanin they are also more susceptible to sunburn.
• At first there are a few clearly defined lesions that may be slightly darker around the perimeter. They increase in size and number becoming confluent and it may be difficult, if they are extensive, to decide if it is a dark person with pale patches or a fair person with pigmented patches.
• Vitiligo can be localised or generalised. If localised it stays within one area that is very roughly a dermatome. If generalised it is far more diffuse and affects both sides of the body. Generalised distribution is commoner.
• The face neck and scalp are most frequently affected.
• There may be a predisposition to occur in sites of repeated trauma such as bony prominences, extensor surface of the forearm, the ventral side of wrists, and the dorsal side of hands and fingers. Mucous membranes may be involved as may lips, genitals, areola and nipples.
• Hair may be white or grey. It is usually in patches on the scalp but can be generalised. Other body hair, including eyebrows, pubic and axillary hair, is less commonly affected.
• Variants include trichrome vitiligo in which there is an area of partial depigmentation as well as the depigmented and normal, so that there are 3 colours. There may be marginal inflammatory vitiligo in which a raised red periphery occurs either at onset or up to a year later. Blue vitiligo may occur with postinflammatory hyperpigmentation that proceeds to vitiligo.

• The diagnosis is generally made clinically.
• Check for evidence of associated disease like diabetes, pernicious anaemia, thyroid disease and Addison's disease.
• A Wood's light can be helpful to exclude superficial fungal infections that fluoresce in the ultra-violet light. Not all fungal infections fluoresce and the colour with which they fluoresce also varies. If a Wood's light is shone on areas of depigmentation the exact margin is more readily seen on fair skin and the lesions appear a bright blue-white. This can be used in occupational screening for vitiligo.⁷

• Use of potent topical steroids
• Leprosy, especially the tuberculous variety
• Piebaldism
• Tinea versicolor
• Tuberose sclerosis

The variety of treatments available suggests that none is totally satisfactory. The response is highly variable between patients.

• Make up and cosmetic camouflage can be very effective but should be used along with high factor sun protection.³
• Despite the fact that topical steroids can cause depigmentation they may be useful in vitiligo as may other topical immunomodulators. These include calcipotriene and tacrolimus.^8,9
• Despite the caveats about burning affected skin and darkening unaffected skin to make lesions more apparent, phototherapy can be useful, especially in early or localised disease where it may be effective in up to 70% of cases. PUVA is often the best choice for widespread disease but treatment is required 2 or 3 times a week for many months to achieve an effective result. The best results are achieved on the face. The backs of hands and the feet are very resistant to treatment. narrow band UV-B and laser has some promising results.³
• Systemic steroids may produce benefit but this has to be carefully weighed against risks.¹
• Combinations of therapy often give better results than single modalities. These include calcipotriol with PUVA and tacrolimus with laser.^10,11
• There seems to be a problem of hydrogen peroxide metabolism and pseudocatalase with calcium cream is effective.¹² However, it needs a vehicle to permeate the skin. First signs of repigmentation take 3 to 4 months. This has been accelerated with climatotherapy which means spending 5 or 6 weeks by the Dead Sea. One study found that the onset of repigmentation was unusually fast, starting at 10 to 16 days.¹³ The mechanisms involved in the beneficial effects produced by climatotherapy remain unclear, but may involve the filtering of natural ultraviolet light in the region, or the mineral content of the sea bed.¹⁴
• If the pale areas cannot be re-pigmented then it is possible to depigment the other areas but this is a desperate measure and is permanent.¹
• Skin grafting can be effective if only small areas are involved.²
• Tattooing and skin dyeing can be technically difficult.²
• Much of this treatment is unlicensed for vitiligo and is not funded by the NHS. The British National Formulary lists just sunblocks and some borderline substances for camouflage under the heading of vitiligo.