Definition
Psoriasis is a chronic, inflammatory skin disease. Knees, elbows, scalp, trunk, and nails are the most commonly affected areas. There are several types of psoriasis.

• Plaque: inflamed patches of skin topped with silvery, white scales (most common type)
• Guttate: small dot-like lesions
• Pustular: weeping lesions and intense scaling
• Inverse: in body folds (armpits, groin, under breasts)
• Erythrodermic: intense sloughing and inflammation of the skin

Psoriasis

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Causes
The cause of psoriasis is unclear. Signals from a defect in the immune system may result in an overgrowth of skin cells. Because the cells grow faster than they can be shed, they "pile up" on the skin's surface. The excess skin cells are thought to cause the silvery white scales that are characteristic of plaque-type psoriasis.

Risk Factors
A risk factor is something that increases your chance of getting a disease or condition.

• Family history of psoriasis
• Cold climates
• Suppression of the immune system, including AIDS
• Certain bacterial infections
• Certain medications, such as beta blockers and lithium

Symptoms
The red, thickened, and rough patches of psoriasis may occur anywhere, but are commonly found on the scalp, elbows, knees, palms, and soles. Other symptoms include:

• Silvery white scales
• Pitted or dented fingernails and/or toenails
• Red lesion in the folds of the buttock
• Joint pain suggesting arthritis

Diagnosis
The doctor will ask about your symptoms and medical history, and perform a physical exam. Your skin and nails will be examined. There are no specific blood tests or diagnostic procedures for psoriasis. Sometimes a skin biopsy will be done to confirm the diagnosis.

Treatment
Treatment is based on:

• The severity of the disease
• The extent and location of the areas involved
• Responsiveness to the treatment

Topical Treatment
Many patients respond very well to treatments applied directly to the skin. Topical treatments include:

• Corticosteroid creams and ointments (most common treatment)
• Synthetic forms of Vitamin D and retinoids (calcipotriene ointment 0.005)
• Retinoids (tazarotene gel 0.05 and 0.1%)
• Coal tar preparations
• Bath solutions and moisturizers
• Tacrolimus and pimecrolimus (especially for inverse psoriasis)

Photo (Light) Therapy
If psoriasis covers more than 30% of the body it is difficult to treat with topical medications alone. Daily, short, non-burning exposure to sunlight clears or improves psoriasis in many people. Sunlight is often included among initial treatments. A more controlled form of artificial light treatment (UVB phototherapy) is often used in more widespread cases. Alternatively, psoriasis can be treated with ultraviolet A (UVA light) and psoralen. Psoralen is an oral or topical medication that makes the body more sensitive to light. This treatment is known as PUVA.

Phototherapy can be very effective in controlling psoriasis but it requires frequent treatments. It may cause side effects such as nausea, headache, fatigue, burning, and itching. Both UVB and PUVA may increase the person's risk for squamous cell and, possibly, melanoma skin cancers. It is unclear whether UVB increases the risk of skin cancer.

Prevention
Psoriasis cannot be prevented.

Avoiding physical trauma to the skin, infections, and cold, dry temperatures may help reduce flare-ups in people with the condition. Your doctor may advise you to avoid certain foods if they appear to make your psoriasis worse.

RESOURCES:

National Institutes of Health
http://www.nih.gov

National Psoriasis Foundation
http://www.psoriasis.org

CANADIAN RESOURCES:

Canadian Dermatology Association
http://www.dermatology.ca/english/

Psoriasis Society of Canada
http://www.psoriasissociety.org/

REFERENCES:

American Academy of Dermatology website. Available at: http://www.aad.org/default.htm .

Current Medical Diagnosis and Treatment . 44th ed. 2005.

de Prost Y. New topical immunological treatments for psoriasis. J Eur Acad Dermatol Venereol . 2006;20(Suppl 2):80-82.

Harrison's Principles of Internal Medicine . 16th ed. McGraw-Hill; 2000.

Varani J, Bhagavathula N, Ellis CN, Pershadsingh HA. Thiazolidinediones: potential as therapeutics for psoriasis and perhaps other hyperproliferative skin disease. Expert Opin Investig Drugs . 2006;15:1453-1468.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Copyright © 2008 EBSCO Publishing All rights reserved.

Edits to original content made by TriVita.