Background/Purpose:  The epidemiology and clinical characteristics of sarcoid arthropathy are not well-described as only referral-based studies have been reported. This study aimed to use the data from a geographically well-defined population to characterize the clinical characteristics of sarcoid arthropathy.

Methods: An inception cohort of patients with incident sarcoidosis in 1976-2013 in a geographically well-defined population was identified based on comprehensive individual medical record review. Inclusion required physician diagnosis supported by histopathology and radiologic features of intrathoracic sarcoidosis, compatible clinical presentation, and exclusion of other granulomatous diseases.  Tissue samples were considered positive if they demonstrate non-caseating granuloma without evidence of acid-fast bacilli or fungi. The only exception to the requirement of histopathological confirmation was stage I pulmonary sarcoidosis that required only radiographic evidence of symmetric bilateral hilar adenopathy. Patients with joint pain were then identified from this cohort. Data were collected on pattern of joint involvement, associated cutaneous and systemic symptoms, physical examinations and inflammatory markers.

Results: In 1976-2013, 345 incident cases of sarcoidosis were identified (mean age 45.6 years and 50.4% female). Symptoms of joint pain occurred in 42 patients (mean age 41.2 years and 57.1% female), and 35 patients had swollen joint(s) on physical examination. Most patients had arthralgia prior to the diagnosis of sarcoidosis with an average time to diagnosis of 21 days. Approximately half of patients had fever and elevated sedimentation rate at diagnosis (48% and 46%, respectively).

Of the 35 cases with objective evidence of synovitis, oligoarthritis (two to four joints) was the most common pattern (88%) followed by monoarthritis (6%) and polyarthritis (6%). Ankles were involved in 91% of cases (14% one ankle and 77% both ankles). In the majority of patients (88%), the arthritis resolved within 6 weeks.    

The most common associated cutaneous manifestation was erythema nodosum followed by subcutaneous nodule/plaque (31% and 5%, respectively). The classic Lofgren syndrome (arthritis, erythema nodosum and hilar adenopathy) was observed in 11 patients (26%).

Conclusion: Inflammatory arthritis occurred in a minority of patients with sarcoidosis. Acute oligoarthritis with bilateral ankles involvement was the most common pattern of sarcoid arthropathy. A significant portion of patients also had systemic symptoms as well as erythema nodosum.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-characteristics-of-sarcoid-arthropathy-a-population-based-study/