Health Knowledgebase

Psoriasis

22nd December, 2008 - Posted by Andy -

Psoriasis is quite a common genetic skin condition affecting 2-3% of the UK population that can look quite ugly if left untreated. It can occur at any point in the lifespan, affecting children, teenagers, adults and older people. It affects males and females equally and approximately 30% of people with psoriasis have a family history of the condition,

Patches of psoriasis (often referred to as plaques) are raised red patches/lesions of skin, covered with silvery white scales. The silvery white scales are the accumulation of the skin cells waiting to be shed, and the redness is due to the increase in blood vessels required to support the increase in cell production.

The condition is very simply a speeding up of the usual replacement processes of the skin. Normally skin cells take about 21-28 days to replace themselves; in psoriasis this process is greatly accelerated, and skin cells can be replaced every 2-6 days. This results in an accumulation of skin cells on the surface of the skin, in the form of a psoriatic plaque. The appearance of psoriasis in sensitive areas, such as the armpits and groin is often red and shiny, with little or no scaling.
It is not unusual for psoriasis to be itchy, and it can sometimes feel painful

Plaques can appear in a variety of shapes and sizes, varying from a few millimetres to several centimetres in diameter and usually have a well-defined edge from the surrounding skin. Most people (80%) with have common plaque psoriasis (also referred to as psoriasis vulgaris – vulgaris just means common) in which the plaques tend to appear most often on the elbows, knees, lower back and scalp, although any part of the body can be affected. Psoriasis is not contagious

Guttate psoriasis patches are small (often less than 1cm in diameter) and scaly, and can be numerous, covering many areas of the body. It is seen most often in children and teenagers and can be triggered by a throat infection. Pustular psoriasis is where small blisters appear, usually on the hands and feet and nail psoriasis where changes in the appearance and texture of the nails occur.

CAUSES
Traditionally psoriasis was thought to be a condition of the upper most layer of the skin (the epidermis), but recent research has found that the changes in the skin begin in the immune system when certain immune cells (T cells) are triggered and become overactive. The T cells produce inflammatory chemicals, and act as if they were fighting an infection or healing a wound, which leads to the rapid growth of skin cells causing psoriatic plaques to form. You may therefore hear psoriasis being described as an “auto-immune disease” or “immune-mediated condition”. It is not yet clear what triggers the immune system to act in this way.

Although certain genes have been identified as being linked to psoriasis, many genes are involved and even if the right combination of genes has been inherited, psoriasis may not appear. A trigger is required for psoriasis to develop and this could be a throat infection, injury to the skin, certain drugs and physical or emotional stress.

VARIOUS TREATMENTS
Treatments depend on the type of psoriasis and/or severity. It is vitally important to use a moisturiser to make the skin more comfortable.

1. Topical therapies
Applied directly to the skin, these are available as creams, lotions, ointments, mousse and gels. Most people with psoriasis will use topical treatments to control the condition. The different categories of topical treatments are:

Vitamin D analogues Coal tar preparations
Topical steroids Dithranol Vitamin A analogues

2. Phototherapy
Is treatment with ultraviolet light - there are two types of ultraviolet (UV) light that can be used to treat psoriasis, UVB and UVA. Treatment with UVA requires a chemical agent (tablet or bath form) called psoralen which makes the skin more sensitive to UVA. This treatment is referred to as PUVA therapy. Treatment with UVB does not need psoralens. You will be required to attend the phototherapy centre 2 or 3 times a week for several weeks if you are receiving UV therapy.

3. Systemic
This refers to drugs which all have potential risks and so are reserved for people with moderate to severe psoriasis. The 4 main UK systemic medications are:

Methotrexate and Hydroxycarbamide- both slow down rate of skin cells divide
Ciclosporin - suppresses the immune system
Acitretin – slows down rate of skin cells divide, plus calms inflammation

4. Biological injections
These treatments are available to treat severe psoriasis that has not responded to any of the aforementioned treatments. They work by blocking the action of certain immune cells (T cells) or the chemicals released by them, which play a part in causing psoriasis.

5. Traditional Chinese Medicine (TCM)
TCM suggests that the following foods create ‘excessive blood heat’ – hot and spicy food, shellfish, chocolate, alcohol, caffeine drinks like coffee and citrus fruits. Similarly over high central heating and excessive stress will make psoriasis plaques worse.

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