Epidemiology, pathogenesis, and imaging of arthritis in children

Pediatric hand ultrasound: common indications, injury, inflammation and masses

Ultrasound is a uniquely valuable tool for evaluating musculoskeletal problems in the pediatric hand. Acute and chronic injuries involving tendons and ligaments of the hand can be quickly assessed and can guide surgical decision-making. Using ultrasound, palpable lesions and masses can be evaluated for cystic and solid components aiding in differential diagnosis. Additionally, ultrasound provides evaluation of acute versus chronic changes of inflammatory arthritis, assessing disease severity and subclinical synovitis and serving as an adjunct to medical management. This review will cover common indications and ultrasound findings of the pediatric hand, focusing on common injuries, inflammatory arthritis and masses. Important anatomical features of the hand will be discussed as well as imaging technique and evaluation in the pediatric patient.

Ultrasonography in the diagnosis and management of patients with inflammatory arthritides

In primary care and internal medicine settings clinicians are often reluctant to take advantage of the resources that ultrasonography (US) offers as a diagnostic tool in the initial management of patients with inflammatory arthritis, despite the recognised importance of an accurate and timely diagnosis of rheumatoid arthritis (RA) and of early referral to ensure optimal patient management. Both grey-scale (GS) and power Doppler (PD) imaging have been extensively used in early detection of synovitis and bone erosions in patients with inflammatory arthritides. We reviewed the main data on the clinical use of US in the initial management of patients with inflammatory arthritis, focusing on RA diagnosis in patients with undifferentiated arthritis, prediction of disease severity, differential diagnoses and assessment of synovitis in children with juvenile idiopathic arthritis (JIA). The role of US in assessing treatment response and monitoring disease activity in clinical remission was also briefly evaluated. The reliability of US as a diagnostic tool in rheumatological diseases has greatly advanced in the last years and the use of this imaging technique, in association with conventional assessments such as physical examination and serological tests, should be considered more often also in primary care settings.

Nocardia brasiliensis infection mimicking juvenile idiopathic arthritis in a 4-year-old girl

Nocardia are ubiquitous environmental saprophytes that cause pneumonia and disseminated disease in immunocompromised patients. They can also cause localized cutaneous and soft tissue infections in healthy people after direct percutaneous inoculation. Nocardia arthritis is rare in both forms of the disease. Here we present the first published case of a child with septic arthritis caused by N brasiliensis. Importantly, this otherwise well 4-year-old girl had no known history of trauma but presented with transient cutaneous lesions and a 6-week history of arthritis involving the right fourth digit proximal interphalangeal joint without accompanying fever or raised systemic inflammatory markers. She received a diagnosis of juvenile idiopathic arthritis and underwent antiinflammatory and immunosuppressant therapy. After 2 months she developed frank septic arthritis, which necessitated a surgical joint washout, from which an intraoperative swab grew N brasiliensis. The patient received 6 months of high-dose trimethoprim-sulfamethoxazole and remains well more than 4 years after treatment. This unusual case highlights the importance of considering an indolent infection from slow-growing organisms, including Nocardia, when diagnosing the oligoarthritis subtype of juvenile idiopathic arthritis. This is especially relevant when a single joint is involved and response to antiinflammatory therapy is suboptimal because antiinflammatory agents may mask evolving signs of infection.