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Flexural psoriasis

Published by Bupa's health information team, August 2008.

This factsheet is for people who have flexural psoriasis, or who would like information about it.

Psoriasis is a common skin condition causing patches of inflamed skin. Flexural psoriasis affects areas where the skin is folded - such as armpits and in the groin area. It is also sometimes called inverse psoriasis.

About flexural psoriasis
Symptoms of flexural psoriasis
Complications of flexural psoriasis
Causes of flexural psoriasis
Diagnosis of flexural psoriasis
Treatment of flexural psoriasis
Prevention of flexural psoriasis
Further information
Questions and answers
Related topics
Sources

About flexural psoriasis

In psoriasis, the rate at which your skin is replaced is rapidly increased.

Your skin is constantly shedding old cells and being replaced with new ones from underneath, in a cycle that usually takes about 28 days. In psoriasis, this process speeds up, only taking about three to four days. New skin cells move rapidly to the surface before they have properly matured, and accumulate on the surface of the skin, forming thick patches called plaques. There is also a build-up of a type of white blood cell (called T-cells) under the skin, which causes inflammation.

Psoriasis can affect any part of the body, but it is called flexural psoriasis when the plaques occur in areas where your skin is folded or rubs together. The skin in these areas tends to be thinner and more sensitive. Flexural psoriasis is commonest in older people.

You may have flexural psoriasis at the same time as having plaques elsewhere on your body. This is called plaque psoriasis (see related topics). Psoriasis is a chronic condition. A chronic illness is one that lasts a long time, sometimes for the rest of the affected person's life.

Symptoms of flexural psoriasis

The plaques in flexural psoriasis are usually red, smooth and may look shiny. The edges are usually well defined. They may be very uncomfortable and painful. Unlike psoriasis plaques on the rest of the body, they don't usually have white scales.

Flexural psoriasis can affect any area where skin is folded or rubs together, such as:

your armpits
under your breasts
in your groin and genital area
between your buttocks

You may also notice changes in your nails, such as:

irregular pitting (the surface of the nail is covered in small pin pricks)
areas of discolouration
your nail may come away from the underlying nail bed

If you think you have any of these symptoms, you should see your GP.

Complications of flexural psoriasis

Up to 10 percent of people with psoriasis also develop associated arthritis (inflamed joints). This is called psoriatic arthritis. Usually the joints at the end of the fingers and toes are affected, although the back, knees and hips may be too. For more information on psoriatic arthritis, please see related topics.

Anyone with psoriasis is potentially at risk of developing a more severe form of the condition, such as pustular or erythrodermic psoriasis (see related topics), although this is rare.

Your psoriasis can also become unstable. This means that you start to develop new plaques and your plaques become bigger, losing their clear-cut edges and sometimes even joining up. In unstable psoriasis, the creams and ointments that you usually use to treat your plaques may start to make your psoriasis even worse. However, it is important that you seek the advice of your doctor before changing your treatment.

Causes of flexural psoriasis

It is thought that substances produced by your immune system cause your skin to start producing new cells faster in psoriasis, as well as causing the build-up of T-cells. But what makes the immune system act like this isn't clear.

You are more likely to get psoriasis if you have a family history of the condition. However in many people, there is no obvious cause.

Flexural psoriasis can come on without any obvious trigger. However, the condition can be aggravated by anything that damages the skin. This can include wearing tight clothing which rubs, or using certain products that may irritate the skin, such as some soaps.

Diagnosis of flexural psoriasis

Your GP will ask about your symptoms and examine you. He or she may also ask you about your medical history.

Usually, your GP will be able to tell whether you have psoriasis just by looking at the affected areas of skin.

If your psoriasis is extensive or severe, if it's affecting your education or work, or if your diagnosis is uncertain, your GP may refer you to a dermatologist (a doctor specialising in conditions affecting the skin).

Treatment of flexural psoriasis

There is no cure for psoriasis, but a lot can be done to help control your symptoms. Your GP will discuss your treatment options with you. It is possible that you may decide you do not need any treatment at all for your psoriasis.

Self-help

Your GP will probably advise you to use emollients. He or she will usually prescribe these, but you can also buy these products from a shop without a prescription. They are very effective in keeping your skin moist, softening scaling and reducing irritation. It is worth discussing the choice of treatment with your GP so that you can get the best results.

Topical therapies

Your GP can also prescribe you a medicated topical preparation (a treatment that is applied directly to your skin, such as a cream or ointment). These are usually the first type of treatment tried.

Preparations for flexural psoriasis are different from those used for plaque psoriasis. This is because the skin in areas affected by flexural psoriasis is thinner, so the treatment doesn't need to be as strong.

Topical treatments for flexural psoriasis include creams and ointments containing:

tar - these can reduce inflammation; however, they can be messy and can irritate the skin in flexures
steroids - these will only be used for controlled periods of time, and your GP will want to monitor your treatment, as the sensitive areas in flexural psoriasis are more prone to side-effects with steroid creams
vitamin D derivatives (such as calcitriol or tacalcitol) - newer types cause less irritation, so are more suitable for sensitive areas
antifungal or antibacterial - some topical treatments are combined with these agents to prevent infections with yeast or bacteria, which can be common in the areas affected by flexural psoriasis

Oral medicines

Your doctor may prescribe one of the following medicines if topical treatments haven't controlled your symptoms; your psoriasis is extensive; or if you have psoriatic arthritis:

methotrexate
acitretin
ciclosporin
hydroxycarbamide

You take these medicines by mouth, and they work by suppressing your immune system, or by slowing down the production of skin cells. They should only be initiated by a dermatologist.

If you are a woman, you will be warned not to become pregnant while taking these medicines or for some time afterwards. With some of the tablets, men will also be advised they shouldn't get their partner pregnant. This is because these medicines can cause serious damage to an unborn baby.

Prevention of flexural psoriasis

Preventing damage to the affected area is important, for example, wearing a condom when having sex can help to prevent flare-ups of flexural psoriasis on the genitals in men. Lubricating jelly can help in women.
Avoid using soaps, gels and scented products in your bath or shower.
After bathing or showering, use a soft towel to pat the area dry, rather than rubbing vigorously.
Wear clean cotton underwear and avoid tight fitting jeans or trousers.

Further information

The Psoriasis Association
0845 676 0076
www.psoriasis-association.org.uk