Psoriasis and Ankylosing Spondylitis

Reviewed by: HU Medical Review Board | Last reviewed: February 2019 | Last updated: June 2019

One of the extra-articular (beyond the joint) manifestations of ankylosing spondylitis (AS) and other spondylarthroses are conditions that affect the skin. The most common skin condition affecting people with spondyloarthroses is plaque psoriasis.1

What is psoriasis?

Plaque psoriasis is a chronic condition causing raised, red, scaly patches on the skin. The plaques may be itchy, painful, and can crack and bleed. Psoriasis most commonly affects the outside of the elbows, knees, or scalp, but it can occur anywhere on the skin or nails.2 Some people with psoriasis just have plaques in one area of the body, while other people may develop plaques in multiple locations.

Psoriasis is not infectious and cannot be spread from one person to another.2 As a chronic condition, psoriasis can cycle through periods of flares and remission. During flares, the plaques may increase in size, number, or intensity. During periods of remission, the plaques may improve or go away completely for a time. Many people find that certain conditions trigger flares, such as stress, injury, or certain medications. Not everyone has the same triggers, but identifying and avoiding individual triggers is important to managing the condition.3

Psoriasis can vary in severity. In mild cases, it affects less than 3 percent of the body. Moderate psoriasis is characterized by covering between 3 and 10 percent of the body, and severe psoriasis covers more than 10 percent of the body. The severity of psoriasis is also determined by how much it affects a person's quality of life. The location of the plaques may impact how a person engages in daily activity. For example, people with psoriasis on their hands and feet may find it difficult to do daily chores or activities.2 Living with a chronic skin condition can have both physical and emotional effects on an individual, and the psychosocial impact of psoriasis can also be significant.

How common is psoriasis in people with AS?

It's estimated that 9% of people with AS have psoriasis.4,5 In some people, psoriasis may occur before symptoms of AS develop. Other people may develop psoriasis after their diagnosis of AS.1 It's possible that these patients may actually have Psoriatic Arthritis, another spondyloarthritis closely related to AS. Their doctor may or may not change their diagnosis, however, these diseases are managed very similarly.

How is psoriasis diagnosed?

Psoriasis is generally diagnosed by a physical examination of the skin, as well as a medical and family history. The doctor may also take a biopsy (a sample of the affected skin) to examine under a microscope. While a general practitioner may diagnose psoriasis, people with skin conditions may wish to consult with a dermatologist, a specialist on skin disorders.2

How is psoriasis treated?

Mild psoriasis is treated with topical treatments, including moisturizers and over-the-counter and prescription creams and shampoos. Moderate to severe psoriasis is usually treated with a combination of approaches, including topical treatments, phototherapy (light therapy), and systemic medications like biologic therapy.2 Some of the biologic therapies used to treat psoriasis are the same medications that are used to treat AS.

In addition to medications, many people with psoriasis incorporate lifestyle changes to help control their symptoms. Identifying and avoiding triggers can help reduce flares, and some people find that dietary changes, regular exercise, and stress management techniques help manage their condition.

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