Plaque psoriasis: symptoms, triggers and treatment steps in the UK

Psoriasis is a long-term inflammatory skin disease. PCDS describes the most characteristic lesions as chronic, sharply demarcated, dull-red, scaly plaques, particularly on the extensor surfaces and in the scalp. Recent research cited by PCDS suggests that psoriasis is an autoimmune disease in which abnormally large numbers of T-cells trigger the release of chemicals in the skin that cause inflammation, redness, itching and flaky patches.

NHS inform explains the consequence for the skin. Skin cells are normally made and replaced every 3 to 4 weeks, but in psoriasis the process takes about 3 to 7 days, which causes a build-up of skin cells and the thick plaques.

Plaque psoriasis is the pattern most people mean when they say psoriasis. Other forms, including guttate, flexural, pustular and nail psoriasis, are described on their own pages.

The NHS says the main symptom is dry, itchy, sore, flaky patches of skin that form silvery-white scales. Plaques are usually 1 to 2cm in size and oval or irregular in shape. On white skin they are pink or red, turning silvery-white; on brown or black skin they are grey, and can leave dark marks on the skin after the psoriasis has gone. Most people have only a few patches, while others have large parts of the body affected.

PCDS describes plaques as symmetrical, on extensor surfaces or widespread, ruby-red and well defined with a silvery (or grey in skin of colour) scale. They can merge to involve very large areas, and scraping off adherent scale may reveal pinpoint bleeding, known as the Auspitz sign. NHS inform adds that in severe cases the skin may crack and bleed, and scalp psoriasis causes thick silvery-white scales and can occasionally cause temporary hair loss.

The NHS says you can get psoriasis at any age, but symptoms often start between the ages of 15 and 25, or 50 and 60, and that there are usually times when symptoms get worse (flare-ups) and times when they are better.

• Raised, sharply defined patches with silvery scale.

• Usually on the elbows, knees, scalp and lower back.

• Itching, soreness or cracking, though some people have no itch.

• Flare-ups that alternate with quieter periods.

• Grey patches and dark marks afterwards on brown or black skin.

Genetics matter. PCDS says a family history is present in 40 to 50% of cases and up to 75% if onset is before age 20. The NHS lists triggers that can cause a flare-up, including stress, drinking alcohol or smoking, living with obesity, being pregnant, certain medicines, infections such as strep A and HIV, cuts, scratches or grazes on the skin, and sunlight. NHS inform adds hormonal changes and medicines such as lithium, some antimalarials, ibuprofen and ACE inhibitors.

PCDS recommends that an assessment of anyone with psoriasis covers severity, the effect on physical, psychological and social wellbeing, whether they have psoriatic arthritis, and modifiable risk factors for cardiovascular disease. It notes that the prevalence of psoriatic arthritis in people with psoriasis may be up to 30%.

NHS inform says a GP will examine the skin to check for psoriasis and that a biopsy is sometimes needed to find the exact cause. A dermatologist may be involved if symptoms are severe or the doctor is unsure, and a rheumatologist if psoriatic arthritis is suspected.

PCDS adds that a solitary plaque that does not respond to topical treatment may need a biopsy to rule out other diagnoses, and that severe or recalcitrant psoriasis is an HIV indicator condition, so a test may be recommended in new severe psoriasis or when treatment is not working as expected.

NICE guideline CG153 sets out the steps. Topical treatment is first-line. For adults with trunk or limb psoriasis it advises a potent corticosteroid once daily plus vitamin D or a vitamin D analogue once daily for up to 4 weeks, and if control is not achieved, a vitamin D analogue alone twice daily, then a potent corticosteroid twice daily for up to 4 weeks or a coal tar preparation. Scalp psoriasis is treated first with a potent corticosteroid once daily for up to 4 weeks.

NICE advises second- or third-line options at the same time when topical treatment alone is unlikely to control psoriasis, for example if more than 10% of body surface area is affected. Narrowband UVB phototherapy is offered for plaque or guttate psoriasis that cannot be controlled with topical treatment, and NHS inform lists systemic non-biological treatments (methotrexate, ciclosporin, acitretin) and biological injections (etanercept, adalimumab, infliximab, ustekinumab) for severe disease.

The NHS lists emollients, vitamin D preparations, steroids and coal tar as the main skin treatments, with light therapy and medicines for more severe disease. NHS inform notes that topical treatments may take up to 6 weeks to have a noticeable effect.

The NHS advises seeing a GP if you have symptoms of psoriasis, if your treatment is not working or is giving you side effects, or if you also have joint pain, stiffness and swelling that keeps coming back.

Some changes need emergency care. The NHS says to call 999 or go to A&E if the skin quickly turns red and white, pus-filled bumps develop and join together, if patches on the feet turn yellow-brown and filled with pus, or if fingers and toes have red scaly pus-filled bumps, especially with a fast heartbeat, high temperature or feeling hot, cold or shivery. NICE says people with generalised pustular psoriasis or erythroderma should be referred immediately for same-day specialist assessment.

The NHS notes that living with psoriasis can be difficult, and that if it affects mental health you may be referred to a mental health specialist. It suggests avoiding triggers, having a balanced diet, exercising regularly, reducing stress, limiting alcohol and trying to stop smoking if you smoke.

PCDS says the clinician should allow time to discuss the condition because it is chronic, and to advise on matters such as a prescription pre-payment certificate where appropriate.

On the NHS, most plaque psoriasis is managed in primary care with emollients and topical treatments, with dermatology referral for severe, widespread or resistant disease. Phototherapy and biological treatments are specialist-led.

Private dermatology is available for quicker assessment and treatment planning. NICE's stepwise approach is the same in either setting, so it helps to ask which step you are on and what would trigger the next.