What is psoriasis?

Psoriasis is a chronic, recurring skin disease. Its scope can vary considerably; from mild outbreaks, where the person may not even be aware they have psoriasis, to severe cases, which can be socially disabling and, in rare instances, life-threatening.

What causes psoriasis?

Psoriasis is a condition which runs in families, but the exact way in which the disease moves from generation to generation has not yet been established. Although the tendency to contract psoriasis is stored in a person's genes, it is by no means certain that it will ever develop.

However, exposure to certain stimuli (such as a streptococcal infection in the throat, alcohol, medicines and local irritation) or damage to the skin, may cause an outbreak of psoriasis in persons who have this genetic predisposition.

What are the symptoms of psoriasis vulgaris?

Psoriasis vulgaris is the most common form. The first signs of an outbreak are:

    * Red spots or patches.
    * The patches grow bigger and become scaly.
    * The upper scales fall off in large quantities, while the lower layers of scales are firmly fixed.
    * When the scales are scraped off, a number of small, bleeding points can be seen underneath.
    * Psoriasis of the nail often manifests itself as small indentures in the nails. The outbreak can be so severe that the nail thickens and crumbles away.
    * Flexural psoriasis occurs in skin folds (flexures). Red, itchy plaques appear in the armpits, under the breasts, on the stomach, in the groin or on the buttocks. The plaques are often infected by the yeast-like fungus candida albicans.
    * Guttate psoriasis is a special variant which primarily occurs acutely in children and young people due to a streptococcal infection of the throat. Drop-like, scaly patches appear on the entire body. In many cases, the condition disappears by itself after a few weeks or months.

Psoriasis of the scalp can be difficult to distinguish from a severe case of cradle cap, and sometimes the two occur simultaneously. An outbreak of psoriasis often leads to lesions on the face.

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Who is most at risk?

People who have family members with psoriasis, especially if they are exposed to stress, alcoholism, infections, medical treatment, or events such as divorce, bereavement or moving house.

How is it diagnosed?

The diagnosis is usually made after a careful examination of the skin.

If there is any doubt about the diagnosis, the doctor will take a biopsy - a small portion of the skin which will be sent to a specialist for examination under a microscope.

What is the treatment?

The treatment, which should be carried out in close collaboration between the patient and the GP or the dermatologist, consists of various treatments used locally on the skin and taken by mouth. It depends on the patient's age, state of health and on the nature of the psoriasis.

Moisturisers are an important factor in treatment for psoriasis and may be all that is needed for mild psoriasis. They reduce dryness, cracking and scaling of the skin.

Specific local treatments include creams and ointments containing coal tar, dithranol, tazarotene (Zorac) or vitamin D-related compounds, eg  calcipotriol (Dovonex), calcitriol (Silkis) or tacalcitol (Curatoderm)).

Occasionally, corticosteroid-containing ointments are used for a short time. Combining a corticosteroid with another topical treatment, either as separate products used at different times of day, or as a combination product, eg Dovobet (calcipotriol and betamethasone) or Alphosyl HC (coal tar and hydrocortisone), may be beneficial for chronic psoriasis vulgaris.

Special lotions are available for scalp treatment. These often contain salicylic acid, coal tar, sulphur or corticosteroids.

Phototherapy (ultraviolet B, UVB) and photochemotherapy (psoralent ultraviolet A, PUVA) are both used in specialist dermatology centres for widespread psoriasis. Many patients find that natural sunlight also helps.

Oral treatment with immunosuppressants such as ciclosporin (Neoral) or methotrexate (eg Maxtrex) or the vitamin A derivative acitretin (Neotigason) may be used for patients with severe, widespread or unresponsive psoriasis.

Injections of the immunosuppressants etanercept (Enbrel), adalimumab (Humira) or infliximab (Remicade) may be used for people with severe plaque psoriasis that has failed to respond to ciclosporin, methotrexate or photochemotherapy, or for people who can't take or tolerate these treatments.

Intensive research is being carried out to find better treatments for psoriasis and new treatments are regularly introduced which improve the condition in some people.