Clinical FeaturesDermatology

What is psoriasis?

Psoriasis is a common skin condition that is thought to affect between 2% and 3% of the population of the United Kingdom and Ireland. It is an immune condition which affects the skin but is also associated with a condition called psoriatic arthritis which affects the joints. However, it is much more than just a skin condition. It can also affect people physically and psychologically.

When a person has psoriasis, the skin replacement process speeds up, taking just a few days to replace skin cells that usually take 21-28 days. This results in an accumulation of skin cells on the surface of the skin, in the form of psoriatic plaques. This process is the same wherever it occurs on the body.

Psoriasis affects men and women equally and can occur at any point in the lifespan, affecting children, teenagers, adults and older people. However, there seem to be two peaks: from late teens to early adulthood and between the ages of around 50-60. It is a long-term condition that may wax and wane. Sometimes it can appear mild and other times it can be more severe. Although there is no cure, it can be managed and with the right treatment and advice, many people are able to live well with the condition.

Usually, a trigger is required for psoriasis to develop, and this could be a throat infection, an injury to the skin, certain medications or physical or emotional stress. There are also others, as triggers can vary from one person to the next.

People who are unfamiliar with the condition sometimes ask whether psoriasis can be transmitted from person to person through contact. The answer is no. Nor can it be transferred from one part of the body to another. However, some people may have a family history of psoriasis and certain genes have been identified as being linked to the condition. Many genes need to be involved though and even if the right combination of genes has been inherited, psoriasis still may not appear.

What does it look like?

Patches of psoriasis, which are often called plaques, are raised red or dark patches of skin, covered with silvery white scales. These scales are the build-up of skin cells waiting to be shed and the redness is caused by the increase in blood vessels required to support the increase in cell production. Psoriasis can range in appearance from mild to severe.

The plaques can appear in a variety of shapes and sizes, varying from very small to several centimeters in diameter. They have a well-defined edge, making it easy to tell where the psoriasis ends, and non-psoriatic skin begins. For some people, plaques may be thin or flat to the skin surface but for others they may be much thicker. It is not unusual for psoriasis to be itchy, and it can often feel painful or sore.

Around 80% of people with psoriasis have plaque psoriasis, with plaques appearing most often on the elbows, knees, lower back and quite often in the scalp. However, there are several different types of psoriasis, and any area of the body can be affected.

Guttate psoriasis, which is most often seen in children and teenagers, can result in small and scaly patches (often less than 1cm in diameter). These can be numerous and cover all areas of the body. This type of psoriasis can be triggered by a throat infection.

Pustular psoriasis is different again and can take the form of small sterile blisters usually on the hands and feet. Nail psoriasis can result in changes to the appearance and texture of nails. In sensitive areas, such as the armpits and groin, psoriasis is often red and shiny, with little or no scaling.

What causes it?

Traditionally psoriasis was thought to be a condition of the uppermost layer of the skin (the epidermis), but now it is known that the changes in the skin begin in the immune system when certain immune cells (T cells) are triggered and become overactive.

The T cells produce inflammatory chemicals and act as if they were fighting an infection or healing a wound, which leads to the rapid growth of skin cells, causing plaques to form. As a result, psoriasis is sometimes referred to as an ‘auto-immune disease’ or ‘immune-mediated condition’. It is not yet clear what triggers the immune system to act in this way.

Links between severe psoriasis and conditions such as diabetes and heart disease have been found but this does not necessarily mean that psoriasis causes these conditions, or that these conditions cause psoriasis. Research is ongoing to try to understand the true nature of this link, why these conditions sometimes occur in the same people and if this is also true of mild or moderate psoriasis.

How can it be treated?

How psoriasis is treated is dependent upon the type and the severity, although the available treatments fall broadly into four main categories.

Topical therapies such as creams, lotions, ointments, foams and gels can be prescribed by a GP and are usually tried first by most people with psoriasis. These can include topical steroids, dithranol, vitamin A and D derivatives and coal tar preparations. If psoriasis is particularly widespread or doesn’t respond to topical treatment, a referral to a dermatologist can take place, who can then offer a wider range of treatment options.

Phototherapy treatment with ultraviolet light can be considered. UVB is the most commonly prescribed although treatment with UVA and the use of a chemical agent called psoralen can also be prescribed. This is referred to as PUVA therapy. Phototherapy treatment can necessitate attendance at a phototherapy centre 2 to 3 times a week for several weeks.

Systemic treatments, which are treatments that are taken into the body, can also be used for moderate to severe psoriasis. The main types used in the UK are methotrexate, ciclosporin and acitretin. All require ongoing monitoring with blood tests and blood pressure checks. They do have potential risks and some cannot be prescribed in conjunction with other medications or if the individual is thinking of having children within the next two years.

Finally, psoriasis treatment has been revolutionised over the last ten years with the increased use of biologics which can be used to treat severe psoriasis that has not responded to any of the abovementioned treatments. Biologics work by blocking the action of certain immune cells (T cells) or the chemicals released by them.

People can also be prescribed biologics if the systemic treatments mentioned above cause side effects which means the person should not take them, or if the person has another condition or medication which means that they should not take the other systemic treatments. There are now over 13 biologics approved by the National Institute for Health and Care Excellence (NICE) for treating severe psoriasis currently available. Additionally, there are a number of biosimilars available for adalimumab, etanercept and infliximab.

Managing psoriasis extends far beyond applying treatments and taking medications. Learning to cope with a skin condition can take time as the psychological impact is not always related to the clinical severity of psoriasis.

It can be reassuring to hear about how other people cope with their psoriasis and live with their condition. The Psoriasis Association, a leading national charity for people affected by psoriasis in the UK, offers help in this regard by funding research, providing information and raising awareness of the condition. The tailored support offered by the charity’s helpline, and peer-to-peer support offered through its website forums and social media platforms can be invaluable.

Everyone has their own way of coping. Some people cover their skin, either with clothing or special skin camouflage make-up, whilst others are comfortable not covering up at all. Some may wear lighter clothes on the top half of their body to hide flakes from scalp psoriasis, whilst for others this is less of an issue. The most important thing is honesty with any healthcare professional offering treatment, especially if experiencing feelings of anxiety or distress due to the impact of psoriasis.

Read the latest edition of Hospital Professional News: August HPN

Catch up on our Clinical Features

Leave a Reply

Your email address will not be published. Required fields are marked *

Please Confirm

This website is only for the eyes of medical professionals. Are you a medical professional?