Psoriasis is a widespread scaly eruption affecting any area of the body and often running in families. Psoriasis is a common condition with an inherited susceptibility in which the exact cause remains unknown. It is not a skin infection and cannot be 'caught by' close contact. Psoriasis is not associated with any internal abnormality of the body. About 2% of the population are affected and this percentage chance of developing the condition is increased if there is a family history of the disorder. For example, if you have psoriasis then the chances of your children developing psoriasis is increased above 2% because they will have inherited the tendency to psoriasis from you. The exact likelihood of your children developing psoriasis is not known, but is probably less than 1 in 10. This likelihood increases if both parents have psoriasis. If you have inherited the predisposition to psoriasis then a wide variety of precipitating factors can bring out the condition. These factors include stress (such as bereavement, work pressures, etc), other illness (such as tonsillitis or hospital admission), and certain drugs. In many patients there is no obvious reason for the appearance of the psoriasis. Psoriasis is not related to diet or to environmental factors such as changes in washing powder, etc.
The typical skin lesions are red, scaly patches varying in size from 0.2 cm to several centimeters in diameter. These scaly patches can affect any site; most commonly the elbows and knees are involved. The scalp is another common site. The nails may become pitted or discolored. The condition tends to wax and wane, sometimes going into spontaneous remission (perhaps for prolonged periods). On other occasions psoriasis seems to go through active periods when it may be particularly difficult to control with treatment. These different phases which the disease might go through can last anywhere from a few weeks to some months. In other words, if your psoriasis is at present going through an active and troublesome phase, this does not indicate that your psoriasis will always be active; usually it will gradually settle down again with some intensive treatment. Some patient's psoriasis does not go through these phases but, if left untreated, would remain about the same for long periods. Almost all patients with psoriasis remain in otherwise excellent health. Psoriasis is not a sign of any internal abnormality and is not associated with any serious threat to your general health. The main aims of treatment are to control the activity of the disease, especially during the bad periods, and reduce the patches to the smallest possible size. It is usually possible to make the patches disappear completely with regular daily treatment. To get the patches to go away may take several weeks of regular treatment and it is very important to persevere and 'get on top' of the condition. It is very important that you dominate the psoriasis and not allow the psoriasis to dominate you. This can usually be accomplished with the help of your Dermatologist. Treatment is usually with topical applications. The word 'topical' means something that is applied to the surface of the skin such as tar or dithranol. Occasionally systemic treatment' is required for particularly severe disease. 'Systemic' means taking something by mouth to act upon the skin from the inside. Systemic treatment has side effects and is only used as a last resort.
Treatment with tar and/or dithranol topical applications are the best treatments for psoriasis. This is because we know that persistent treatment with these things will lead to improvement in nearly every case. The word 'persistent' is very important because if the treatment is only applied halfheartedly (for example, only twice per week), then the chances of success are very much reduced. Tar and dithranol treatments have several important advantages over other treatments for psoriasis such as corticosteroid creams. These advantages include no development of resistance to treatment and no serious side effects. These two properties are very different to corticosteroid creams which can have important side effects on the skin and can also lose their effectiveness as time goes by when the disease gets used to the corticosteroids. If you use corticosteroids for prolonged periods and your psoriasis becomes resistant to their effects, then you will need stronger and stronger corticosteroid creams to control the disease, leading to a vicious circle situation. A further important advantage of tar and/or dithranol over other treatments is that once the psoriasis is under control with tar or dithranol, the tendency for the disease to remain quiet for prolonged periods is much greater. In other words the 'rebound effect' when treatment is stopped is much less than with steroid-type creams. Both natural sunlight and artificial sunlight treatment may lead to considerable improvement but you should be wary of artificial sun beds and ask a Dermatologist's advice before starting treatment. There is no known 'cure' for psoriasis (though psoriasis is at the centre of many skin research programmes) and all available treatments are effective for only a temporary period. Sometimes that period can be many months or years during which no further treatment may be needed. If and when the psoriasis becomes active again, the same treatments can simply be used again. There is no resistance to the beneficial effects of tar and dithranol which are the two best treatments for the condition. There are certain situations in which corticosteroids are definitely indicated for psoriasis and under these circumstances this type of treatment can be very good. Usually steroids should be used for only 2 - 3 weeks in this way. Psoriasis is very common and often poorly treated - this condition can usually be controlled and may require expert advice - you can get my expert opinion and recommendations.
by Dr John Ashworth - Consultant Dermatologist