So long, psoriasis!

Is a rash psoriasis?

First, make sure the rash really is psoriasis. “Psoriasis can look similar to other inflammatory skin conditions, such as types of eczema, a fungal infection or lichen planus,” Dr McPherson says. Indeed, psoriasis may resemble diseases as diverse as atopic dermatitis (allergic eczema), seborrhoeic dermatitis, fungal skin infections (tinea; ringworm), some cancers and secondary syphilis. Certain clinical clues help. Lichen planus, for instance, causes shiny, raised, purple-red blotches on the limbs or body, and white patches in the mouth or hair loss.

The various forms of psoriasis complicate diagnosis. Chronic plaque psoriasis, also called psoriasis vulgaris (vulgaris is Latin for common), is the most frequent type. Uncommon forms include guttate, erythrodermic and pustular psoriasis. “Psoriasis can generally be recognised by the appearance of the rash and the areas of skin affected. Plaque psoriasis typically affects elbows, knees, scalp, armpits, breasts, tummy, belly button and genitals. Although psoriasis mostly causes localised skin inflammation, it can be very widespread,” Dr McPherson explains.

“The skin plaques classically appear as raised, red areas with clear borders [well-demarcated] and significant scales, which can appear ‘silvery’,” Dr McPherson adds. In skin of colour, the plaques appear grey, purple or lilac. “When psoriasis improves it tends to leave pale areas on skin,” she remarks.

In about half of people with plaque psoriasis, the disease impacts the nails, which may separate from the fingers or toes (which can be difficult to see in skin of colour), show orange-yellow discolouration (oil spots) or crumble. Sometimes, distinguishing fungal nail infections (onychomycosis) from psoriasis can be tricky. Patients should see their GP if there is any doubt about the diagnosis or the psoriasis seems to be worsening.

Under psoriatic skin

Psoriasis arises from the interaction of genes and environment. Scientists identified about 80 genes that influence the risk of developing psoriasis. Without an environmental trigger, psoriasis does not develop. Stress, infections (especially streptococcal), alcohol, smoking, certain medicines (including lithium, antimalarials and non-steroidal inflammatory agents), sunlight, weight gain and obesity can all trigger psoriasis in some genetically predisposed people.

Researchers do not fully understand how genes and environmental triggers interact to cause the self-sustaining inflammation characteristic of psoriasis. However, certain cytokines, small signalling proteins that help control immune responses, drive psoriatic inflammation. Two cytokines, interleukins 17 and 23 (IL-17 and IL-23) are particularly important in psoriasis. Medicines targeting IL-17 and IL-23, and another cytokine called tumour necrosis factor alpha, transformed management of severe and chronic plaque psoriasis.

Psoriatic inflammation can affect parts of the body other than the skin and nails. For example, between 10-40 per cent of psoriasis patients develop arthritis, usually in their finger joints. A person with psoriasis and unexplained joint pain or swelling should see a doctor as soon as possible. “If the patient presents evidence of joint inflammation, they will need a referral to secondary care, as the joint disease can be destructive, and treatments should be considered early on,” Dr McPherson says. 

Psoriasis, especially plaques on the face, palms, soles or genitals, can dramatically undermine wellbeing. Not surprisingly, people with psoriasis are more likely than the rest of the population to be depressed. Inflammation, which contributes to many conditions associated with psoriasis, also increases the risk of depression. “The impact of psoriasis varies between people and, to some extent, depends on how severe and widespread it is,” Dr McPherson says.

“As with many chronic skin conditions, psoriasis can have a huge impact on many people’s self-esteem, mental health, quality of life and intimate relations. The impact can be cumulative and life-long in some people. They may avoid activities, increasingly restricting their lives. It is vitally important that patients struggling with psoriasis understand that they have done nothing wrong, which is key for their ability to live full lives and get the right treatments and support to reduce the impact of psoriasis.”

Treating psoriasis

Topical (applied to the skin) formulations are the foundation of psoriasis management, even in people using other treatments. The most appropriate formulation depends on the extent and type of psoriasis. For example, people with large areas of psoriasis may benefit from creams, lotions or gels. Ointments are best for thick scale. Lotions, solutions or gels are suitable for the scalp and other hairy areas.

Advise people with psoriasis that topical treatments may take several weeks to start working. Patients also need to appreciate that the psoriasis may relapse if they suddenly stop using topical treatments. “If patients do not see an improvement after one to two months, or if the skin condition is getting worse, then we would suggest getting further support and advice on other treatment options – this may have to be via their GP,” Dr McPherson suggests.

“Although there is no cure for the tendency for psoriasis, there are multiple treatment options for psoriasis, including over-the-counter (OTC) moisturisers [emollients] to help with dryness on their skin. Mild-to-moderate topical steroids can be helpful for facial psoriasis and are available OTC. For more severe or persistent cases, a GP can prescribe treatments for psoriasis that are not available OTC or refer to a dermatologist,” says Dr McPherson.

Topical treatments alone may not control psoriasis, especially if more than 10 per cent of body surface area is affected. In adults, the front and back of one arm and hand, the chest and the stomach each equal about nine per cent of the body’s surface area. GPs may prescribe a more potent steroid than those available OTC, a drug related to vitamin D (e.g. calcipotriol) or both. You should stress the importance of using the medications as advised and ensure patients know how to apply treatment. Adherence can be particularly poor with topical treatments.

Dermatologists can offer other treatments such as: phototherapy with ultraviolet light; injected or oral drugs that suppress the immune system or reduce inflammation (e.g. ciclosporin, methotrexate, acitretin and apremilast); or ‘biologics’ targeting the cytokines that drive psoriasis (e.g. etanercept, secukinumab and ustekinumab). So, patients should see their GP if the psoriasis does not improve sufficiently.

Lifestyle changes

“It cannot be overstated that a genetic tendency is the main reason for psoriasis. The person has not ‘done anything wrong’ to get psoriasis,” Dr McPherson says. “With this in mind, lifestyle advice for people with psoriasis should be supportive and non-judgemental. There is, however, a link between psoriasis and obesity and heart issues, particularly in older patients. Lifestyle advice about keeping a healthy weight, eating a balanced diet, limiting alcohol intake and taking regular exercise are even more important in people who have psoriasis. In some people, this can reduce how bad their psoriasis is, how much it impacts them, as well as how they respond to treatments and long-term risks.”

People with psoriasis may benefit from other lifestyle changes including smoking cessation, improved sleep and reducing salt. The Journal of the European Academy of Dermatology and Venereology recently reported that each extra gram of sodium intake – equivalent to about 2.5g of table salt (sodium chloride) – increases psoriasis risk by 18 per cent to 47 per cent. Sodium deposited in the skin may trigger psoriatic inflammation. Reducing salt also lowers the likelihood of hypertension and stroke, which, as we’ve seen, are particularly common in people with psoriasis.

As these examples show, our understanding and treatment of psoriasis is continually evolving and pharmacy teams can play a crucial role. “Keeping informed and your knowledge up to date is important,” Dr McPherson concludes.