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Susceptibilities in Afro-Caribbean skin

A GP quizzes an expert to take a topical issue beyond the textbook

When considering race and skin, how should we group in terms of pigment and skin type?

Thinking about skin type is useful when considering degree of pigmentation. A standard way of classifying skin is from type one (pale skin/red hair/lots of freckles) through to type six (darkly pigmented Afro-Caribbean with afro hair type). I like to think of racial groups in the context of certain diseases; this is particularly relevant when considering the hair and the scalp.

I don't find terms like Caucasian helpful as there is so much confusion about what this means and it doesn't necessarily describe skin type.

How is Afro-Caribbean skin different?

It is obviously darker and more pigmented than white skin types, around which most dermatological textbooks are written. This can alter the appearance of certain skin problems. The hair follicles grow in a spiral, which can make it more vulnerable to, and influence the appearance of, certain scalp diseases.

The skin ages in a different way because it is protected against sun exposure.

Afro-Caribbean patients tend to be slightly more susceptible to childhood eczema, and it is often more severe ­ especially in the UK.

How should we approach inflammatory hypo- and hyperpigmentation?

This is a common problem, especially in Afro-Caribbeans. They are important sequelae to appreciate as disfigurement can last for several months after the skin has settled. In a patient with acne, because of the subsequent post-inflammatory hyperpigmentation, we are more aggressive in our management at an earlier stage. Although the marks are not scars, they take months ­ even years ­ to fade. The patient may look for skin-lightening products that often contain steroids and make their condition worse by re-exacerbating the acne.

In scaly skin conditions, I recommend liberal amounts of moisturisers, even more so than for a white skin. This is to prevent the eruption being exacerbated by scratching which leaves behind more pigmentation. Lichenification from chronic scratching looks more disfiguring in black skin than white but is symptomatically very similar. Management is the same, with topical steroid and occlusion with either a dressing or bandage, if necessary, to get rid of thickened skin and prevent more damage.

Sometimes I find it difficult to assess lesions on a black skin because they don't look red, or like the textbook images on white skin.

It can be difficult to appreciate erythema. I suggest looking for a violacious hue or purple colour when looking at pigmented skin and with practice you can see an increased vascularity. If you think it is lichen planus you might go on to look at their nails or in their mouth for more clues.

Pityriasis alba on children's faces often concerns parents. What can we do about it?

Patches of depigmentation on the face known as pityriasis alba are a variant of atopic eczema, particularly in children. This condition reflects small subtle patches of eczema on the face that lead to post-inflammatory hypopigmentation ­ which is what is seen. Preceding acute eczema may not be evident. Management is around emollients with a bit of topical steroid to prevent the eczema.

It is more striking in the summer but sunscreen will help prevent highlighting following sun exposure.

In pityriasis alba, skin will re-pigment if the eczema is controlled but, as it is a continuing atopic diathesis and the eczema lesions can be subtle, it can be an ongoing problem. It usually settles with time and children grow out of it.

In contrast, pityriasis versicolor hyperpigmentation can take up to six months to settle. But if there is hypopigmentation the skin will repigment in the sun quickly once you have got rid of the yeast.

Some patients treated for inflammatory dermatoses complain that the skin preparations we prescribe have damaged or bleached their skin, especially with steroids in children. What they are often describing is post-inflammatory hypopigmentation. It is worth mentioning this before you start treatment.

What about psoriasis?

This is a problem in darker skin types because when it occurs hyperpigmentation is marked. Management is similar but emollients are very important to reduce scratching that leads to koebnerisation or psoriasis in the damaged skin.

What about 'natural' products?

Skin-lightening products are available in marketplaces around the country. They are not always legal and may contain potent steroids of the order of Betnovate or Dermovate. They do lighten skin but tend to cause problems like acne, striae and telangectasia.

We've had a particular problem in our area with an African import called Wah-Wa. We analysed samples patients had given us and found it contained dexamethasone. If a patient mentions they have a natural product that makes a skin disease better within 24 to 48 hours I assume it contains a steroid until proved otherwise.

Is there a particular role for the new products tacrolimus and pimecrolimus?

These are exciting but their place in the eczema treatment battery is not absolutely clear. We have had good results using them on some Afro-Caribbean children with eczema when it is tolerated. Unfortunately tacrolimus can sting and tends to deter some patients.

Managing scalp ringworm

Has there been a resurgence of scalp ringworm?

There is an epidemic in UK inner cities with population clusters of Afro-Caribbeans. Trichophyton tonsurans spreads from child to child, unlike ringworm from animals which is sporadic. It produces a myriad of signs including: localised hair loss that is slightly scaly and studded with a broken-off expanded hair bulb (like black dots in the middle of the bald patch); diffuse dandruff-like appearance; diffuse pustules and lymphadenopathy (often mistaken for a bacterial folliculitis) and a boggy kerion like an abscess.

I teach that any scaly scalp condition in a black child is ringworm until it is shown not to be. Research here at King's suggests widespread prevalence among black children is to do with hairstyling practices.

Children in south-east London have their hair cut in hair-type groups. After isolating fungus from clippers we found it was more common if children used hair oils. This might be a vehicle for spreading fungal spores in the family.

Treatment is griseofulvin for eight weeks (10-25mg per kg in a divided dose after food). It was once available as a syrup but this was discontinued ­ but it is possible to get a suspension. Terbinafine is still only available as a tablet. It is not licensed for children ­ I'm not sure why as all the studies have been done. We use it and it's on the British Association of Dermatologists' guidelines for managing ringworm.

Current guidelines suggest it should be taken daily for a month, but a recent study suggested two weeks might be enough. Topical antifungals like ketocomizole may help increase mycological clearance and decrease transmission, but not by themselves.

How can we help folliculitis keloidalis and pseudofolliculitis barbae?

Folliculitis keloidalis, bumps that appear on the back of the scalp with short hair, are a real problem. Close shaving and subsequent ingrowing hairs probably cause it. These set up a localised foreign body inflammatory reaction, complicated by over-exuberant scar formation or even keloids. The problem didn't exist when long hair was popular. We recommend not shaving the scalp and check for staphylococcal carriage. If there is no improvement after three to six weeks, we use topical or intralesional steroid. Management remains frustrating and disappointing.

Pseudofollicultis barbae probably has a similar pathogenesis. I suggest a shaving oil to shave, shaving in the direction of the hair growth and using an electric razor if possible. I also suggest an emollient containing an antiseptic, such as Dermal 500. Antibiotic and steroid regimes may dampen it down.

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