Psoriasis
Psoriasis is a condition where there is over activity of the cells in the skin responsible for production of keratin - called keratinocytes - with a resultant increase in blood flow and inflammation. The increased blood flow and inflammation make the affected skin look red, while the over-production of the cells means that more dead skin is produced, so the area is scaly. The exact cause is unknown but it is thought that both genetic and environmental factors are involved. While any part of the body from the scalp to the soles of the feet may be affected it is commoner on the elbows and knees. Individual patches may be very small, or cover a large area. As with other skin conditions it may worsen during times of stress and during the winter months. In young people with a genetic predisposition to psoriasis it may follow a throat infection or exposure to certain drugs like beta-blockers, when it presents as large numbers of small scaly lesions on the trunk and the limbs - a condition called guttate psoriasis; it usually resolves over a period of weeks. In a proportion of people with psoriasis there is involvement of the joints, causing arthritis (which may be severe in the hands, called arthritis mutilans) or fingernails. More rarely the psoriasis may become severe and affect more than 90 per cent of the body surface, possibly involving the formation of pustules full of sterile inflammatory fluid - a severe condition requiring vigorous medical attention.
The management of psoriasis depends on the type and severity. Isolated patches may respond to topical treatments based on vitamin D or coal tar, with or without steroids. Guttate psoriasis affecting the whole body may benefit from ultraviolet light treatment while more severe generalised psoriasis may require treatment using medication to suppress the activity of the immune system.
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