Psoriasis is a common skin disorder which affects about 2% of the population. It occurs equally in men and women and can affect people at any age. It is characterised by red patches on the skin covered by silvery white scales. These patches mainly occur on the knees, elbows, back or scalp, but almost any area of the body may be involved.

• Although the patches are unsightly and may sometimes appear to be embarrassing, the disorder is not infectious and with care and proper treatment the condition can usually be brought under control.
• Although the exact cause of psoriasis is still unknown, it appears that some people are more inclined to develop the disorder than others. Many patients are able to think of someone else in the family who has psoriasis but it is thought that people with family history of the disorder only get it themselves if some other factor starts it off. One of these factors could be a throat infection, especially in children. Stress is another factor which could bring about psoriasis for the first time, and it can also be responsible for a relapse later on.
• In most cases, exposure to sunlight improves the condition but sunburn may actually bring about a relapse. Diet is not thought to have any effect on psoriasis.
• There are certain times in life when the tendency to develop psoriasis is increased. Children with a family history of psoriasis may well develop the condition at puberty. Women may find that their psoriasis becomes less noticeable during pregnancy, but that it flares up again soon after childbirth. Women are also more prone at or after the menopause.
• The skin is a complex organ consisting of various layers of different types of cells. The cells in the outer layer of the skin gradually change and move towards the surface where they are being continuously shed and replaced. The process normally takes between 3 and 4 weeks. In psoriasis, this rate of turnover is dramatically increased, within a localised areas of skin, to as little as 3-4 days, both live and dead cells arrive at the surface together and accumulate to form the silvery white scales that are characteristic of psoriasis.

Treatment:

Scalp

• Usually a coconut oil and coal tar solution compound is used in association with a tar shampoo. The compound (usually Ung Cocois Co) should be rubbed into the scalp thoroughly at night and washed out in the morning with the tar shampoo.
• Tar shampoos (like Polytar, Capasal) take 7-14 treatments to clear scalp psoriasis, but it will still be necessary to continue treatment once or twice a week to prevent relapse in most cases. The use of a shower cap will help to keep the pillowcase clean. Use old linen!

Nails

• There is no treatment.

Body

• Calcipotriol is often the treatment of choice for mild to moderate psoriasis. The ointment may need to be used twice a day for 8weeks. It commonly causes a temporary skin irritation, especially when used on the face.

Face

• Usually a weak steroid cream or ointment will be prescribed and should be used twice a day.

Plaques on limbs and trunk

• The first line of treatment in most patients is some form of dithranol. Usually this will be applied initially for 30 minutes and then washed off. Dithranol stains the skin, clothing and bath fitments.
• In most cases this is very effective, although some patients will not respond adequately and in some patients the psoriasis is too extensive for them to manage this home treatment themselves.
• For such patients treatment may be offered in the outpatient treatment unit at Hospital. Patients come each day for 1-2 hours for treatment. This consists of a tar bath, ultra-violet light and the application of dithranol in a stiffer base than that used for short contact treatment. A tube gauze dressing suit is made and the dithranol is left on for 24 hours. The treatment is repeated every day Monday to Friday. Eighty-five per cent of patients are clear of psoriasis within 10-15 treatments. The dithranol stains clothing and linen, but the tube gauze suit should largely prevent this problem.
• In the 85% of patients that clear after a course of dithranol treatment they should remain free of psoriasis on average for about 4 months, although some patients have a spell of freedom from psoriasis for much longer and in some patients it is rather shorter. For many patients 2 or 3 treatments per year keep their psoriasis under acceptable control.
• What can be offered for the severe psoriasis patient (ie those with at least 20% of their body surface covered) and who do not respond to dithranol or who having responded to dithranol flare up too quickly to make it a practical treatment?
• The choices are
  Photochemotherapy (PUVA)
  Methotrexate or similar drug.
  Retinoids like acitretin (Vitamin A derivatives) with or without PUVA
  Hydroxyurea
  Cyclosporin A.

All these treatments are effective but are only used under strict supervision and only after the other simple and well tried treatments have been used first. They all have side effects, these and also the details of the treatments will be discussed with you, if at any stage your psoriasis requires these more potent treatments.

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