psoriasis - General Information
psoriasis is a chronic skin disorder which affects between 1 and 3% of the population the cause of which is unknown. It is not contagious, but is more likely to occur in individuals whose family members have it. It is found in both males and females, and in all age groups. The word psoriasis is derived from the Greek word meaning itch. It results from an overproduction of skin cells leading to thickening of the skin (plaques) and scaling.
Silvery plaques occur most frequently on the scalp, elbows, knees, genitals, arms, legs and nails. The lesions will frequently appear on both sides of the body, in the same areas. psoriasis can affect the nails by pitting the surface, separating the nail from the nail bed, and thickening or crumbling the nail plate. When it occurs in the nail it is difficult to treat. Another form of psoriasis is flexural psoriasis, which occurs in the armpit, under the breast, in skin folds, around the groin, in the cleft between the buttocks and around the genitals.
About 5% of psoriasis sufferers have arthritis. Some have specific rheumatic diseases unrelated to psoriasis, but others can develop joint deformities as part of the psoriasis. The arthritis of psoriasis sometimes improves when the skin manifestations of the disease improve. Anti-inflammatory medication may be helpful.
How does it occur
The cause of psoriasis is unknown. It is thought that a biochemical malfunction triggers the excessive skin cell production. In a person with this condition, a skin cell matures in 3 to 4 days instead of the normal 28 to 30 days. This causes an abnormal outer layer of skin, which is seen as round or oval red patches of skin covered with silvery scales.
In severe cases, a process known as lichenification occurs, whereby the skin becomes thickened and hard.
Even though the cause of psoriasis is unknown, there seems to be a genetic or family tendency in many sufferers, which is somehow related to a defect in the production of the epidermal (top) layer of the skin. For instance, brothers and sisters of psoriasis sufferers have an 8% risk of developing the condition, a 16% risk if one parent has it and a 50% risk if both parents also have psoriasis.
people often experience an attack if their skin is injured (e.g. cut, scratched, rubbed, severely sunburned). Such a flare-up will occur 10 to 14 days after the skin is irritated. psoriasis can also be triggered by some infections (such as a streptococcal throat infection) and by certain drugs (including lithium and propranol). Stress - in the form of significant life events - can also precipitate psoriasis.
How is it diagnosed
Diagnosis of psoriasis is made by examining the skin and noting specific characteristics of the lesions. Occasionally a small piece of skin (or skin scrapings) may need to be removed (a biopsy) and examined in the laboratory.
What is the treatment
At present there is no cure for psoriasis, but treatment can be very helpful in alleviating the symptoms. Your Gp or specialist will discuss an individual treatment plan that takes into account your overall medical condition, age, lifestyle, severity and duration of the psoriasis and expectations of treatment.
Various treatments, combinations of treatments, and a number of visits to the Gp or specialist may be necessary before the condition comes under control. The goal in treatment of psoriasis is to relieve discomfort and slow down rapid cell division. Treatment varies according to the extent of the disease.
- Bland moisturising creams and lotions (emollients) prevent water in the skin from evaporating, improving the skin's appearance and controlling the itching often produced by dry skin. These are easy to use and free of side-effects
- Coal tar preparations are available in a variety of forms but tend to be messy and difficult to use. They may stain clothes and bed linen
- Dithranol is a cream applied to the skin plaques. It may cause staining of skin and may irritate unaffected skin
- Steroid creams are sometimes used generally only for short periods of time on stubborn plaques that fail to respond to other preparations
- Calcipotriol (Dovonex) cream ointment or scalp application is effective in two-thirds of patients. It does not cause staining but may irritate the skin
- pUVA. This stands for psoralens and Ultraviolet A irradiation and is offered to patients with psoriasis which is resistant to the other types of treatment. It involves the patient taking a drug called 8-methoxypsoralens 2 hours before being exposed to a carefully administered dose of ultraviolet A irradiation given in a special walk-in cabinet. This is usually repeated a number of times and has been shown to be highly effective in 85% of patients. Eye protection is worn during treatment
Who is at risk
psoriasis affects all races, and males and females equally. It appears to be most common in northern Europe and Scandinavia (3% of the population) and rarest in North American Indians (0.5% of the population). It occurs significantly more amongst relatives of people with psoriasis as illustrated above. Twin studies have shown that if one twin has the condition there is a 72% chance that the other twin will also develop it.
Two researchers - Henseler and Christophers - have proposed two forms of psoriasis:
- Type I is hereditary, and has an average onset age of 16 years for females and 22 years for males. It has a strong tendency to follow an irregular course and become generalised.
- Type II is sporadic; it has a peak incidence at 60 years of age.
Where can I obtain further information
Apart from contacting your own Gp the following organisation may be of help:
7 Milton Street
Tel: 01694 711129
- HENSELER, T., CHRISTOpHERS, E.F. (1985) psoriasis of early and late onset characterisation of two types of psoriasis vulgaris, Am Acad Dermatology, 13 pp.450-56
- (1994) Mosby's Medical, Nursing and Allied Health Dictionary 4th ed Mosby Year Book
- GREAVES, M.W., & WEINSTEIN, G.D.(1995) Treatment of psoriasis, New England Journal of Medicine, 332 (9), pp.581-7.