Psoriasis

by Jill Shuman, MS, RD, ELS

Definition

Psoriasis is a chronic, inflammatory skin disease. It speeds up the life cycle of skin cells and cause scales and red patches. Psoriasis can come and go over time. There are several types of psoriasis:

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

Psoriasis

Causes

The cause of psoriasis is unclear. Signals from the immune system may cause the change in skin cells. The cells grow faster than they can be shed and pile up on the skin's surface. This pile up causes the patches.

Risk Factors

Psoriasis may be more likely in those with one or more of the following:

Family history of psoriasis
Cold climates
Certain bacterial infections
Certain medications such as beta blockers, tumor necrosis factor-alpha inhibitors, and lithium
Smoking
Skin injury
Suppression of the immune system

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 or rashes in folds of skin
Joint pain suggesting arthritis

The skin may also be sore, burning, or itchy depending on the type of psoriasis.

The rashes and lesions may come and go.

Diagnosis

You will be asked about your symptoms and past health. A physical exam will be done. It will include an exam of skin and nails. The doctor may make a diagnosis based on the appearance of the skin. There are no specific blood tests or diagnostic procedures for psoriasis. A skin biopsy may be done to confirm the diagnosis.

Treatment

Treatment will be based on how severe it is and how much skin in involved. Choices may include:

Topical Treatment

Topical medicine is applied directly to the area. It may help to slow growth of patches or manage irritation. Other treatment may help eases itchiness or irritation. Choices include:

Corticosteroid creams and ointments (most common treatment)
Synthetic forms of vitamin D
Retinoids
Coal tar preparations
Bath solutions and moisturizers
Tacrolimus and pimecrolimus (especially for inverse psoriasis)

Photo (Light) Therapy

Psoriasis over large areas can be hard to treat with lotions or creams. Sunlight can help to clear or improve skin patches. The time in the sun should be managed to prevent sunburn.

Phototherapy can provide same benefits in a more controlled way. A form of phototherapy called PUVA uses a special light and a medicine that makes the body more sensitive to light. Phototherapy requires many treatments. It may cause side effects such as nausea, headache, and fatigue, burning, and itching. It can also increase the risk for skin cancer.

Systemic Treatment

More severe psoriasis may need medicine that has a wider impact on the body. Choices include:

Methotrexate—A affects the whole immune system. It should not be taken by pregnant women, women planning to become pregnant, or by their male partners.
Cyclosporine—Another type of systemic medication that suppresses the immune system to slow the turnover of skin cells. It should not be taken by pregnant or breastfeeding women.
Hydroxyurea—Less toxic than methotrexate or cyclosporine, but may be less effective.
Systemic retinoids—Compounds with vitamin A-like properties taken internally may be prescribed in severe cases. Retinoids can cause birth defects, and women must protect themselves from pregnancy for several years after completing treatment. Systemic retinoids are often combined with phototherapy for increased effectiveness and for their property of being protective against squamous skin cancer.
Newer medications include biologic agents such as adalimumab, etanercept, and infliximab, which affect a part of the body's immune response by targeting certain cells in the immune system that cause inflammation.

Prevention

Avoiding physical trauma to the skin, infections, and cold, dry temperatures may help reduce flare-ups in people with the condition.

RESOURCES:

American Academy of Dermatology
https://www.aad.org

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

CANADIAN RESOURCES:

Canadian Dermatology Association
https://www.dermatology.ca

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

References:

Moderate to severe psoriasis and psoriatic arthritis: biologic drugs. National Psoriasis Foundation website. Available at: https://www.psoriasis.org/about-psoriasis/treatments/biologics. Accessed January 26, 2021.

Psoriasis. American Academy of Dermatology website. Available at: https://www.aad.org/public/diseases/scaly-skin/psoriasis. Accessed January 26, 2021.

Psoriasis. DynaMed Plus website. Available at:
...(Click grey area to select URL)
Accessed January 26, 2021.

Systemic medications—methotrexate. National Psoriasis Foundation website. Available at: https://www.psoriasis.org/about-psoriasis/treatments/systemics/methotrexate. Accessed January 26, 2021.

Last reviewed November 2020 by EBSCO Medical Review BoardNicole S. Meregian, PA
Last Updated: 1/26/2021

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