Acute oligoarthritis with bilateral ankle involvement was the most common clinical presentation of sarcoid arthropathy, according to data derived from an inception cohort of patients.1

Although joint involvement is a known component of sarcoidosis, the clinical characteristics of the resulting inflammatory arthopathy have not been evaluated in a regional population, as most studies have used patients from single referral centers or specialty arthritis clinics.  To describe the clinical characteristics associated with sarcoid arthropathy in a well-defined population, researchers analyzed data from an inception cohort of patients from the Rochester Epidemiology Project, which included the population of Olmsted County, Minnesota.

A standardized data form was used to collate deidentified patient data, including age at diagnosis, sex, ethnicity, smoking status, duration of followup, the presence of intrathoracic disease, radiographic findings, the pattern and duration of joint pain, the presence of objective evidence of synovitis (swelling), the presence of fever, associated cutaneous manifestations, angiotensin converting enzyme level, serum calcium, and erythrocyte sedimentation rate at time of diagnosis.


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Sarcoidosis cases were identified by diagnosis codes related to sarcoid, sarcoidosis, and contextual noncaseating granuloma.  Individual medical records were then reviewed to verify the sarcoidosis diagnosis, including histopathologic evidence.  An exception to the need for biopsy-proven sarcoidosis histopathology was made for patients diagnosed with stage I pulmonary sarcoidosis, where radiographic evidence of symmetric bilateral hilar adenopathy was accepted.

In this population, 345 incident cases of sarcoidosis were diagnosed between 1976 and 2014. Joint pain was seen in 12% of these patients, with 35 of these patients presenting with overtly swollen joints. The majority of patients had onset of arthralgia prior to the confirmed diagnosis of sarcoidosis, with average lag time to diagnosis of 21 days. 

In the 35 patients with swollen joint(s) on physical examination, the most common arthritic pattern identified was oligoarthritis involving 2 to 4 joints (88% of cases), with monoarthritis and polyarthritis representing another 6% of these cases, respectively.   Involvement of the ankles were noted in 91% of cases.  Most cases of sarcoid arthropathy resolved within 6 weeks, demonstrating a relatively favorable prognosis.

Summary and Clinical Applicability

When inflammatory arthritis occurs in patients with sarcoidosis, it is most likely to be an acute oligoarthritis presenting with bilateral ankle involvement.

Limitations and Disclosures

Limitations inherent to retrospective data analysis and reliance on accurate recording of joint examination by the treating physician exist. Generalizability to populations outside this single county, which was notably predominantly Northern European in ancestry, has yet to be evaluated. 

“The clinical presentation of sarcoidosis varies among different ethnic groups; the results of the current study might not be generalizable to other populations, particularly those with a greater proportion of African Americans,” the authors cautioned.

Reference

1.  Ungprasert P, Crowson CS, Matteson EL. Clinical Characteristics of Sarcoid Arthropathy: A Population-Based Study. Arthritis Care Res (Hoboken). 2016;68(5):695-9.