Psoriatic Arthritis and Rheumatoid Arthritis

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psoriasisWhat is Psoriatic Arthritis?

Psoriasis is an autoimmune disease which causes a red, itchy, scaly rash. Most frequently, the rash, called plaque, appears on elbows and knees. Some people with psoriasis also develop symptoms which are similar to Rheumatoid Arthritis. This is classified as a separate disease called Psoriatic Arthritis (PA).

According to the National Psoriasis Foundation, up to 30 percent of people with psoriasis develop Psoriatic Arthritis. I found several other sources which say it is as low as 5%. There are 5 distinct classifications of Psoriatic Arthritis based upon which joints are affected and type of joint destruction involved. Some types of PA cause severe deformity and disability.

Last month, we introduced you to Ankylosing Spondylitis, which is in a branch of the rheumatic disease family called seronegative spondarthropathies. If we call AS a cousin of RA, then Psoriatic Arthritis would be a sibling to Ankylosing Spondylitis. Genetic markers are used rather than apparent symptoms to determine how closely the conditions are related.

Is There a Typical Psoriatic Arthritis?

Eighty-percent of the time, psoriasis symptoms appear first. However, in some patients, the psoriasis is barely even perceptible. Or only the nail tissues may be affected.

Like RA, PA symptoms can vary greatly between patients. Psoriatic Arthritis may be symmetrical or asymmetrical. The spine and sacroiliac joints may or may not be involved. Fingers and toes may swell into a sausage-shaped deformity called dactylitis. A very destructive hand deformity called arthritis mutilans is caused by destruction of joint tissue. (Mutilans can also be caused by Rheumatoid Arthritis.)

How is Psoriatic Arthritis like Rheumatoid Arthritis?

  • Usually consists of a pattern of alternating flares and remissions
  • Runs in families, showing a probable genetic cause
  • Specific causes or triggers are unknown
  • Can result in joint destruction and severe disability
  • Can also be found in a kids’ size called Juvenile Psoriatic Arthritis / JPA
  • TNF plays a significant role in destruction of tissue
  • Treatments for PA include a traditional pyramid of medications consisting of NSAIDs, corticosteroids, DMARDs, and immunosuppressant drugs including the modern class of medications called Biologics

How is Psoriatic Arthritis different from Rheumatoid Arthritis?

  • Rheumatoid factor is negative 95% of the time with PA
  • Psoriatic Arthritis affects genders more equally than RA
  • Most RA patients eventually get rheumatoid nodules; Most PA patients get painful rashes and 80% of the time that includes nail damage
  • Rheumatoid Arthritis rarely affects the DIP joints close to the fingernail, but Psoriatic Arthritis does more frequently.

Fascinating facts about Psoriatic Arthritis

  • Smoking and drinking alcohol are believed to make psoriasis or Psoriatic Arthritis worse.
  • The arthritis symptoms and the psoriasis symptoms of PA frequently flare on separate schedules.
  • Juvenile Psoriatic Arthritis affects girls more than boys, although the adult version of PA is less discriminating.
  • DIP joints and spondarthropathy (spine-related) symptoms are more common in men with PA than women with PA.
  • Women are more likely to have symmetrical arthritis, similar to Rheumatoid Arthritis.


Personal note: one of my first RA friends does not actually have Rheumatoid Arthritis, but Psoriatic Arthritis. Have you noticed that those of us who have an illness which is part of a family of autoimmune diseases often feel like we are connected to one another in a special way? It is not only the diseases which are similar; we have similar concerns and experiences. I have been ever more grateful for people who “get it”.

More psoriasis info:

Easy to read PA explanation for laymen: Mayo clinic PA article

Although psoriasis on the elbow and knee may be typical, I knew there are more severe cases. So I found a page with some photos, but be warned: they are a bit shocking. Shocking psoriasis images    

Related posts:

Another seronegative spondylarthropathy: Ankylosing Spondylitis and Rheumatoid Arthritis

Precautions for living on DMARDs: Preventative First Aid for Rheumatoid Arthritis

Modern view of treatment for autoimmune diseases Pyramid Approach to Rheumatoid Arthritis Trashed

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Kelly Young. All rights reserved.

This entry was posted on Thursday, October 8th, 2009 at 8:19 am and is filed under RA Research, Resources, and Rheumatology. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.


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