A new study investigating the frequency and characteristics of sarcoid arthropathy, in which sarcoidosis is accompanied by joint disease, revealed that a majority of patients with sarcoidosis also have sarcoid arthritis.
The study “The clinical characteristics of sarcoid arthropathy based on a prospective cohort study” was published in the journal Therapeutic Advances in Musculoskeletal Disease.
The cause of sarcoidosis is unknown, but it involves abnormal activation of the immune system causing granulomas to form (granulomas are groups of white blood cells called macrophages in tissues), which can affect different parts of the body, causing a range of symptoms in different patients. Sarcoid arthritis (arthritis is a painful inflammation of the joints) occurs in some cases of sarcoidosis.
Sarcoidosis usually is more severe in the African-American population in the U.S. than in the white population, and also is more frequent (35.5 versus 10.9 per 100,000 people).
The study included 114 patients (36 male) with sarcoidosis; 106 of these patients had joint pain. Sarcoid arthritis was diagnosed in 71 of the patients, mainly with involvement of two to four joints (oligoarthritis). Eleven patients also had other rheumatic diseases (diseases affecting the joints or connective tissue).
In the majority of the patients (78.9%), arthritis was gone within six weeks. Most of the patients were treated with non-steroidal anti-inflammatory drugs or oral steroid-based drugs, for a short period. Arthritis lasting more than six weeks was reported in 24 (21.1%) of the patients.
“Acute sarcoid arthritis was seen in 71 (62.3%) patients, while chronic arthritis occurred in 24 (21.1%) patients. Oligoarthritis was the most common pattern of joint involvement, and bilateral ankle arthritis was the prominent feature. The prognosis of sarcoid arthropathy was generally favorable, as the arthritis resolved within six weeks in the majority of patients,” the authors wrote.
Arthritis occurred more often in females. It also occurred more often in patients with erythema nodosum, another condition seen in 53 of the patients that involves red lumps on the lower legs.
“Inflammatory arthritis occurs in a majority of patients with sarcoidosis. Acute arthritis with bilateral ankle involvement is the most common pattern of sarcoid arthropathy. Sarcoidosis can mimic many primary rheumatic diseases or may coexist with them.” the team concluded, adding that a diagnosis of sarcoid arthropathy should be considered when sarcoidosis patients have complaints concerning their musculoskeletal system.