Background/Purpose: Musculoskeletal (MSK) involvement occurs in up to 70% of childhood-onset systemic lupus erythematosus (cSLE). MSK ultrasound (US) has emerged as a tool with greater sensitivity than clinical examination for detecting MSK abnormalities in adult SLE. To date, rare case reports and case series have assessed MSK US in cSLE populations, including small sample sizes, limited anatomical scope or restricted to nondominant side evaluations. Therefore, the objectives of this study were to assess MSK US findings in cSLE patients and healthy controls, focusing on joints, tendons, and entheses sites. We also evaluate demographic, clinical, laboratory and treatment parameters in MKS clinically symptomatic compared to asymptomatic cSLE patients.

Methods: A cross-sectional study was performed in a tertiary and university center, evaluating 63 consecutive cSLE patients(ACR1997 and SLICC 2012 criteria) and 20 healthy controls. US evaluations were performed by two experienced sonographers, assessing 36 MSK structures/participant, including 20 joints, 8 tendons, and 8 entheses (Logic 7-GE- Milwaukee, Wisconsin, USA). ML6-15 MHz and hockey stick L8-18i-D MHz linear array probes were used for images on dominant and nondominant subject sides. MSK US abnormalities were defined according to OMERACT criteria. Patients’ records were reviewed for demographic, clinical, laboratory, and therapeutic data.

Results: Median age[14.6(13-16) vs. 13(11-16)years, p=0.099] and female sex(73% vs. 55%, p=0.902) were similar in cSLE patients and heathy controls. MKS US abnormalities were significantly higher in cSLE compared to controls(79.4% vs. 5%, p < 0.001), likewise synovitis(34.9% vs. 5%, p=0.009), tenosynovitis(66.7% vs. 0%, p < 0.001) and enthesitis(28.6% vs. 0%, p=0.004). The most frequent MKS US findings in cSLE patients were knee synovitis(14.3%), wrist extensor tenosynovitis(17.4%), fibular tenosynovitis (20.6%) and quadriceps enthesitis(18.2%). Further analyses of MSK US findings showed significantly higher frequency of enthesitis(50% vs. 15.4%, p=0.003) in clinically symptomatic compared to asymptomatic cSLE. The frequencies of any MSK US abnormalities(87.5% vs. 74.4%, p=0.337), synovitis(41.7% vs. 30.8%, p=0.378), and tenosynovitis(75% vs. 61.5%, p=0.271) were alike in clinically symptomatic compared to asymptomatic cSLE patients. No differences were observed between the groups regarding demographic data, SLEDAI-2K, antiphospholipid antibodies, cumulative dose of glucocorticoid and immunosuppressive use (p >0.05).

Conclusion: Our findings demonstrate a high frequency of MSK US abnormalities in cSLE, particularly involving periarticular soft tissues. Subclinical involvement highlights the utility of ultrasound in the early detection of silent abnormalities, which may be important for the diagnosis of both inflammation and structural damage, monitoring and management of cSLE. Further longitudinal studies are necessary to assess the potential of MSK US in predicting disease progression and its impact on treatment decisions.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/synovitis-and-periarticular-soft-tissues-abnormalities-in-childhood-onset-systemic-lupus-erythematosus-an-ultrasonography-study/