Psoriasis is generally categorised into one of three severities based on the extent of body surface covered. Where 2% of the body is affected, it is classified as mild, where 3-10% of the body is covered, it is classified as moderate and where more than 10% of the body is affected, the disease is classified as severe. Based on these criteria, approximately 25-30% of patients have psoriasis, which is considered moderate to severe.

1. Family history (genetics)
This is the most well established risk factor for the development of psoriasis. Approximately 40% of patients with psoriasis have a family history amongst first-degree relatives. It has also been noted that psoriasis develops in as many as half of the siblings when both parents have psoriasis, this falls to 16% when only one parent is affected, and 8% when neither parent is affected but there is an affected sibling.

2. Infections
Bacterial and viral infections may be linked to psoriasis; however, beyond streptococcus, the role of other infections in precipitating psoriasis has not been studied [4, 6].

3. Alcohol and smoking
Some studies have suggested smoking or alcohol as a cause of psoriasis. Although a large proportion of these studies have been case-control studies, based on a typical group of patients admitted to hospital, in a population based study, alcohol was shown to be a significant risk factor for mortality among patients suffering from psoriasis. Not only that, alcohol has been associated with worsening of skin disease after drinking in men and women and treatment failures. Alcohol seems to affect dermatological diseases such as psoriasis by influencing metabolism, cutaneous vasculature (arrangement of blood vessel around the skin), and the immune response. Alcohol intake can lead to liver dysfunction, when the liver cannot get rid of toxins as a result of this, the different systems in the body are affected, including the skin. The skin, trying to purge itself of toxins may result in an immune related disease, such as psoriasis. It is quite possible that alcohol may alter the expression of psoriasis and its clinical course. Abstinence from alcohol can induce remission [4, 6, 8].

The role of smoking as a risk factor for psoriasis remains elusive. According to Neimann et al (2006) in 1992, researchers in the UK evaluated 108 patients with new psoriasis and compared rates with matched controls in the community. They showed a significant association between smoking "prior to onset" and psoriasis.

Although it has often been implicated in the pathogenesis and progression of the disease, conclusive data on the role of smoking is currently lacking. As indicated by some studies, whether or not smoking causes psoriasis, cessation probably does not alter the course of the disease [4, 6].

4. Trauma
Psoriasis may appear at the sites of trauma, including sites of sunburn, following surgery or biopsies, or even after simply scratching an area.

5. Stress
Recently, stress has been implicated in the acceleration or in accelerating the worsening of psoriasis, as can be found in many other diseases with complex natural history. Although this factor has not been robustly studied, the view that stress is a significant factor in the natural history of psoriasis is widespread, particularly among patient groups.

6. Drugs
Although drug exposure has not been well defined as a risk factor for new incidence of psoriasis, some drugs have been reported to worsen pre-existing cases of psoriasis. These drugs include lithium (mood stabilising drug) and antimalarials [4, 6].

2. Guttate psoriasis
From the Greek word gutta meaning droplet, Guttate psoriasis presents as small patches (2-10 mm diameter) of psoriasis all over the body. Accounting for about 2% of the total cases of psoriasis, it usually occurs shortly after a throat infection (streptococcal infection of the pharynx or tonsils) and can be the presenting episode of psoriasis in children or, occasionally, adults. The number of patches manifested in this type of psoriasis varies and can range from 5 or 10 to over 100.

3. Flexural psoriasis
This affects the flexures (skin folds e.g. under breasts), and have lesions, which are devoid of scales and appear as red, shiny, well demarcated plaques.

4. Generalised pustular psoriasis
This is a rare type of psoriasis, which represents active, unstable disease. It is characterised by anti-inflammatory changes in the psoriatic sites and lesions are presented as small, red, circular patches, filled with pus. Patients often present with a fever and usually need to be admitted to the hospital for management as it can be a life-threatening condition with a variety of consequences, including hypothermia (dangerously low body temperature) [4, 5].

5. Erythrodermic psoriasis
This is a serious but rare complication of psoriasis. It may take one of two forms,
a) Chronic plaque psoriasis, which may gradually progress as plaques become confluent (run together) and extensive, or
b) A manifestation of unstable psoriasis brought about by infection, tar, drugs, or withdrawal from corticosteroids (a synthetic drug similar or identical to a natural corticosteroid, used to reduce inflammation and control allergic disorder).

It is one of the few emergencies involving skin conditions as it may impair the thermoregulation capacity of the skin, leading to hypothermia (dangerously low body temperature), high output cardiac failure and metabolic changes such as anaemia due to loss of iron and vitamin B12. Patients suffering from this rare disease are usually admitted to the hospital [4, 5].

6. Palmoplantar pustulosis
This presents as sterile, yellow pustules (small round raised area of inflamed skin filled with pus) on a background of abnormally red skin caused by local congestion (as in inflammation) and scaling, which affects the palms and/or soles of the feet. Pustules are tender and fade to form dark brown colouration with scales or crusts, which adhere to them. Palmoplantar pustulosis most commonly affects women, presents most commonly between the ages of 40 and 60 years and is associated with current or past smoking in up to 95% of subjects.

(It is now believed however that palmoplatar pustulosis may not be a form of psoriasis) [4, 5].

7. Psoriatic nail disease
This usually affects the fingernails much more than toenails. The most common finding is small pits (as of a thimble) in the nail plate, resulting from defective nail formation in the proximal portion (near to the point of attachment) of the nail matrix. Orange-yellow areas may also be present beneath the nail plate; these are referred to as "oil spots". The nail plate may become thickened, opaque and discoloured.

The disease not only complicates millions of lives, it also disrupts countless interpersonal relationships. Fouere et al (2005) made mention of the fact that previous research have confirmed that more than 80% of patients suffering from psoriasis expressed difficulties in establishing social contacts and relationships being the worse aspect of their psoriasis. Psoriasis sufferers often feel stigmatised by the condition and this in itself contributes to everyday disability leading to depression and sometimes suicidal ideation in more than 5% of patients. According to Langley et al (2005), recent work has identified that pathological worry and anxiety occur in at least a third of patients with psoriasis. Psychological interpersonal difficulties have also been found to severely affect all aspects of the patient's daily life. Engaging in avoidance behaviours and the belief that they are being evaluated on the basis of their skin disease, both contribute to stress in patients [3, 5].

1. Patches of red skin covered with silvery white raised scales often on the knees, elbows trunk or scalp. These may become itchy, painful and can sometimes crack and bleed.

2. Fingernails and toenails can be affected, including discoloration and pitting of nails.

3. Small areas of bleeding where skin is scratched.

4. Patients can sometimes suffer with arthritis (see Psoriatic arthritis in associated diseases).

1. Sun exposure, which improves the appearance of psoriasis, particularly mild psoriasis.

2. Prescribed creams and lotions, including topical steroids, dithranol, tar preparations, emollients, topical vitamin D3 analogues such as calcipotriol and tacalcitol, and salicylic acid.

3. For moderate to severe psoriasis, which are generally less responsive to the above, more intense treatment are required in the form of,

¢ Prescribed medication including methotrexate, cyclosporin and acitretin.

¢ Phototherapy (light therapy) such as PUVA (psoralen and Ultraviolet A), UVA, UVB and Narrowband UVB sun beds.

¢ Herbal medicines, Chinese herbs, Homeopathic treatments

4. If triggered by throat infection, antibiotics will help.

1. Keep skin well moisturised, to prevent the skin drying

2. Avoid soap and harsh detergents

3. Wear natural fibres, such as cotton, next to the skin

4. Enjoy the sunshine, don't hide your skin away

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