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Palindromic rheumatism (PR) is a rare type of inflammatory arthritis that is closely related to rheumatoid arthritis (RA). PR causes sudden attacks of joint pain and swelling of the joints and surrounding tissues, usually in the hands and feet. These attacks typically recur.
The name comes from the root word “palindromic,” which means “to come and come again.” When you’re not having a palindromic rheumatism episode, your joints will feel and appear normal on an X-ray. Episodes may last for days or just a few hours, and symptom-free periods can last weeks or months. Although PR can recur over many years, unlike RA, it rarely causes permanent joint damage. When it does occur, PR usually affects just two or three joints.
Palindromic rheumatism affects men and women equally, typically between the ages of 20 and 50. Half the people who have it eventually go on to develop RA. Due to the “on and off” nature of the disease and lack of visible joint damage, diagnosis of PR can be challenging. It is typically diagnosed when all other potential causes of the person’s symptoms have been ruled out.
Researchers do not know what causes Palindromic rheumatism. To date, no common thread has been found among people with the disease, so it’s impossible to determine who will and won’t develop it. However, a few risk factors have been identified, such as age (most often occurring in people aged 20 to 70); gender (men and women are equally affected); and rheumatoid factor protein (people with this protein are more likely to develop PR).
Researchers believe PR is strongly connected to RA because people with Palindromic rheumatism often have many of the same protein markers as people with RA. It is believed, therefore, that PR may be one of several rheumatic diseases related to RA. Some research suggests a link with antiphospholipid syndrome, in which the immune symptom mistakenly produces antibodies against normal proteins in the body. Studies show that during a PR attack, inflammatory cells move into the lining of the joint similar to what happens with wounds.