Psoriasis Fact Sheet

Main Category: Eczema / Psoriasis
Article Date: 29 Oct 2006 - 0:00 PST

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Psoriasis is a chronic skin disease. It typically goes through cycles of remission and recurrence. Plaque psoriasis, the major type of psoriasis, results when skin cells called keratinocytes start overproducing and accumulating on the surface to create plaques.

Psoriasis is a disorder of the immune system, which is estimated to affect about 125 million people globally1. In Singapore, it is estimated that at least 40,000 people have psoriasis2. Approximately 10% of patients who have psoriasis also develop an associated inflammation of their joints, which is known as psoriatic arthritis3.

CAUSES

While the exact cause of psoriasis is unknown, the disease is considered a chronic immune disorder in which certain immune cells become overactive and release proteins called cytokines and chemokines. Tumor necrosis factor (TNF) is a cytokine involved in the body's normal immune response to infection. In patients with psoriasis, TNF is overproduced, which causes inflammation that also drives the formation of often painful and potentially disfiguring skin plaques.

Due to genetic factors, certain people are more likely to develop psoriasis, but a "trigger" is usually associated with onset and recurrence. These triggers may include emotional stress, some types of infection, or reaction to certain drugs.

SYMPTOMS

Psoriasis usually results in patches of thick, red, and/or inflamed skin covered with silvery scales known as plaques. These patches often itch or feel sore and can occur anywhere on the body. Common sites for plaques include the elbows, knees, lower back, and buttocks. The disease may also affect nails and the soft tissues of the genitals and the inside of the mouth.

LIFE IMPACT

In addition to the negative physical impact, psoriasis can also affect people's feelings, behaviors, and experiences, which can have social and economic consequences. Many people are not aware that the impact on a psoriasis patient's physical and mental functioning can be similar to that of those with cancer, heart disease, diabetes, hypertension, arthritis, or depression. Some of the ways that psoriasis can affect daily living include:

-- Itching and pain can interfere with basic functions, such as brushing hair, walking, or sleeping.

-- Plaques on hands, feet, and face can hinder individuals from holding certain jobs, playing some sports, and caring for family members or a home.

-- People with moderate to severe psoriasis may feel self-conscious about their appearance and have a poor self-image.

-- According to Gladman, up to 42 percent of psoriasis patients have psoriatic arthritis, which causes joint pain.

DIAGNOSIS

It is important for patients with psoriasis symptoms to consult a general practitioner (GP) or dermatologist for a definitive diagnosis. In most cases, diagnosis can be confirmed by a physical examination. Diagnosing psoriasis may be difficult because it can look like other skin diseases. In these circumstances, confirming the diagnosis by examining a small skin sample under a microscope may be necessary.

TREATMENT OF PSORIASIS

Doctors generally treat psoriasis based on the severity of the disease, type of psoriasis, and the patient's attitude toward and response to initial treatments.

Conventional treatments for psoriasis include topical therapies (such as ointments and creams containing corticosteroids or coal tar), phototherapy (ultraviolet radiation), and systemic therapies (such as methotrexate or cyclosporine) taken by pill or injection. These treatments can have limitations that may prohibit long-term use.

Newer biological therapies, such as etanercept, have been approved recently to treat moderate to severe forms of the disease. A TNF-blocker, etanercept, works on the body's immune system and can be very effective for severe psoriatic arthritis, significantly improving the patient's condition and inhibiting disease progression.

TYPES OF PSORIASIS

Psoriasis may be one of several types: plaque, guttate, pustular, inverse, or erythrodermic.

-- Plaque psoriasis - This is the most common form of psoriasis, occurring in more than 80 percent of psoriasis patients, and is characterized by skin lesions. These lesions appear red at the base and are covered by silvery scales.

--Guttate psoriasis - This type of psoriasis is characterized by small, drop-shaped lesions and affects about 10 percent of patients with psoriasis. Guttate psoriasis is often triggered by certain types of infection.

--Pustular psoriasis - Pustular psoriasis can be generalized and can include fever, malaise, and superficial pustulation; or it can be localized and have pustules on the palms and soles. Occurring in less than three percent of patients, pustular psoriasis is often triggered by the withdrawal of systemic steroid therapy.

--Inverse psoriasis - Inverse (also known as intertriginous) psoriasis manifests as smooth, red patches that may occur in the folds of the skin near the genitals, under the breasts, or in the armpits.

--Erythrodermic psoriasis - The widespread reddening and scaling of the skin that occurs in patients with erythrodermic psoriasis may be a reaction to the withdrawal of the use of systemic corticosteroids or other medications. This type of psoriasis is potentially serious or life threatening. Erythrodermic psoriasis affects fewer than three percent of patients.

REFERENCES

- Greaves MW, Weinstein GD. Treatment of psoriasis. Drug Therapy. 2004;32:581-588.
- Christophers E. Psoriasis-epidemiology and clinical spectrum. Clin Exper Derm. 2001;26:314-320.
- Mease P. TNF therapy in psoriatic arthritis and psoriasis. Ann Rheum Dis. 2004;63:755-758.
- Lebwohl M. Psoriasis. Lancet. 2003;361:1197-1204.
- Stern RS. Psoriasis. Lancet. 1997;350:349-353.
- Rapp SR, Feldman SR, et al. Psoriasis causes as much disability as other major medical diseases. J Am ACAD Dermatol. 1999:361:401-407.
- Fredriksson T, Pettersson U. Severe psoriasis - oral therapy with a new retinoid. Dermatologica. 1978;157:238-244.
- Finlay AY, Khan GK. Dermatology life quality index (DLQI) - a simple practical measure for routine clinical use. Clin Exper Dermatol. 1994;19:210-216.
- Nickoloff BJ, Nestle FO. Recent insights into the immunopathogenesis of psoriasis provide new therapeutic opportunities. J Clin Invest. 2004;113:1664-1675.
- Psoriasis Association of Singapore. "About Psoriasis". Available at www.psoriasis.org.sg/whatis.htm. Accessed Oct. 17, 2005.

1 National Psoriasis Foundation "About Psoriasis - Statistics" Available at
www.psoriasis.org/about/stats
Accessed 6 October 2006

2 National Skin Centre "About Psoriasis". Available at
www.nsc.gov.sg/cgi-bin/WB_ContentGen.pl?id=171
Accessed 4 October 2006.

3 www.medicinenet.com/psoriatic_arthritis/article.htm
author: William C. Shiel Jr., MD, FACP, FACR Accessed 4 October 2005.

National Psoriasis Foundation

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