Psoriasis - What Is It? Who Gets Psoriasis?

Main Category: Eczema / Psoriasis
Also Included In: Dermatology
Article Date: 28 Oct 2004 - 16:00 PST

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Here are Some Psoriasis Fast Facts

1) Psoriasis is a chronic disease affecting 1 in 50 people worldwide

2) It is not contagious -no one can 'catch' it from another person

3) It can be painful, itchy, unsightly and highly distressing - it can ruin people's lives

4) Psoriasis generally affects joints, limbs and scalp, but it can appear anywhere and even cover the whole body

5) There is currently no cure for psoriasis

6) Effective medicines exist to control the symptoms. However, no one medicine works in all people and psychosocial needs of patients are often ignored

7) Nearly a quarter of people with psoriasis go on to develop psoriatic arthritis

What is psoriasis?

Psoriasis is a non-contagious, common, chronic and incurable skin disease that occurs when faulty signals in the immune system cause skin cells (keratinocytes) to regenerate too quickly - every three to four days instead of the usual 28-30 day cycle. These extra skin cells build up on the skin's surface, forming red, flaky, scaly and inflamed lesions that can itch, crack, bleed and be extremely painful. These lesions can be very disfiguring, causes others to stare and discriminate against people with psoriasis. The disease generally affects joints, limbs, genitalia and scalp, but it can appear anywhere and even cover the whole body.

As well as these physical effects, it can also have a significant, life-ruining impact on a patient's quality of life.1 In a National Psoriasis Foundation (US) survey, people with psoriasis reported that living with the disease might be worse than many other chronic conditions such as coronary heart disease or chronic obstructive pulmonary disease (COPD); the only condition that they deemed worse was depression.2

The disease comes in many different forms and is categorised by doctors as either mild, moderate or severe, depending on the level of scaliness, redness and percentage of body surface area involved. The severity of the disease is also commonly measured in clinical trials by using an objective scaling system called PASI (Psoriasis Area and Severity Index), which takes into account signs such as redness, plaque thickness and scaling. The PASI is scored on a point system of 0 to 72, with higher numbers being more severe.

PSORIASIS DISEASE SEVERITY

Mild
Psoriasis patients affected (%) - 75-80
Body surface area covered (%) - <2
PASI score (max = 72) - <10

Moderate
Psoriasis patients affected (%) - 15-20
Body surface area covered (%) - 2-9
PASI score (max = 72) - 10-50

Severe
Psoriasis patients affected (%) - 5-10
Body surface area covered (%) - >10
PASI score (max = 72) - 50-72

Who gets psoriasis?

Some form of psoriasis affects 1 in 50 of the world's population - up to 125 million people.3 All ethnic groups are affected. The disease often appears between the ages of 15 and 35 years, but it can develop at any age. In fact, about 10-15% of those with psoriasis get it before age 10 years and occasionally it appears in infancy.

What are the different forms of psoriasis?

There are several distinct forms of psoriasis, which not only have different appearances, but also may require different types of treatments.

Cutaneous (skin) manifestations

Plaque psoriasis (75-80% of psoriasis cases)3: This is the most common form of psoriasis. It is characterised by raised, thickened patches of red skin covered with silvery-white scales. The most commonly affected areas include the knees, elbows, scalp, behind the ears, sacrum, navel, between the buttocks and genitalia.

Guttate psoriasis (15-20%)3: This form of the disease most commonly occurs in children. It is characterised by droplet-shaped lesions that range in diameter and some very thin scales, which are found mainly on the trunk and may involve the face.

Pustular psoriasis (2%)3: This is a difficult-to-treat, less common form of psoriasis that generally occurs in older patients.3 It may present as new or as a flare up of plaque psoriasis and involves areas of reddened skin, particularly on the hands and soles of the feet.

Erythrodermic psoriasis (1-2%)3: This is characterised by inflammatory lesions that may cause extreme reddening of all or most of the body. It generally occurs in people with chronic plaque psoriasis and has an average age of onset of 50 years.3

Scalp psoriasis (approximately 50%)3: This is a plaque-type psoriasis. Due to the thickness of the psoriasis, It is very difficult to treat because topical formulations do not penetrate well.

Inverse psoriasis: This form is typically found in folds or creases (i.e., armpits or groin, under pendulous breasts or in skin folds of obese patients). Its lesions are usually smooth and red, but do not have scaling.

Extracutaneous (non-skin) manifestations

Psoriatic arthritis (approximately 23%)3: this is a specific type of arthritis, which causes inflammation and swelling primarily in the hands, feet or in larger joints such as the knees, hips, elbows, and the spine. It may cause stiffness, pain, and joint damage. It is rare that a person can have psoriatic arthritis without having psoriasis.

Nail psoriasis (Up to 50% [80% in patients with psoriatic arthritis])3: this is characterised by large, deep, random pits of the nail plate. In one study, nail psoriasis was the first sign of disease in 4% of patients, but nail changes eventually occur in most patients.

What causes psoriasis?

Although we have known about psoriasis from biblical times, no one knows exactly what causes psoriasis, but it is believed to have a genetic component (40-60% of patients have a family history of psoriasis).1 Also, a variety of factors are known to induce psoriasis or make it worse, including psychological stress, skin trauma, medications and infections.1

For many years psoriasis was thought to be a mainly epidermal disease (a disease of the skin cells). However, it was discovered that drugs that suppress the immune system helped treat psoriasis. Furthermore, it was discovered that cyclosporin, which suppresses the activity of T-cells (white blood cells), is effective in treating psoriasis. This has drastically changed notions about the underlying development of the disease and several lines of evidence now point to a prominent role for T-cells.

Most researchers agree that the immune system, which normally protects the body against foreign invaders, is somehow mistakenly triggered and begins targeting skin cells. This fault speeds up the growth cycle of skin cells and instead of falling off (shedding) the cells pile up and form the lesions. Because of this reason, psoriasis is often called an 'immune-mediated' disease.

How is psoriasis diagnosed?

There is no blood test for psoriasis. Physicians usually diagnose it by examining the affected skin. Less often, a small piece of skin affected by the psoriasis is cut out and examined under a microscope.

http://worldpsoriasisday.com

References

1 Cather JC, Menter A. Modulating T cell responses for the treatment of psoriasis: a focus on efalizumab. Expert Opin Biol Ther 2003;3:361-370.

2 Krueger G, Koo J, Lebwohl M et al. The impact of psoriasis on quality of life. Results of the 1998 National Psoriasis Foundation patient-membership survey. J Am Acad Dermatol 2001;137:280-284

3 Tankosic T, Sharma D. Immune and Inflammatory Disorders Study 35. Psoriasis and Associated Arthropathy. Decision Resources, Inc, May 2001.

4 Biondi Oriente C, Scarpa R, Pucino A et al. Psoriasis and psoriatic arthritis. Dermatological and rheumatological co-operative clinical report. Acta Dermatol Venerol 1989;146(suppl):69-71.

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