CASE 64
By: Dr. Amna Kashgari MD,SSC-Rad
HISTORY: A 7-year-old girl complaining of right knee pain and swelling for 2 months.
What are your findings?
What is your differential diagnosis?
What is your most likely diagnosis?
FINDINGS:
Frontal and lateral plain radiographs (A) of the knees show mild enlargement of the epiphysis of the right knee with periarticular osteopenia and joint effusion.
Sagittal fat-suppressed T2-weighted (B) and sagittal contrast enhanced fat-supressed T1 weighted (C) MR images of the right knee demonstrate a large joint effusion with hypointense debris layering dependently within the effusion. There is enhancing synovitis but no enhancement of the layering debris (rice bodies secondary to chronic inflammation).
DIFFERENTIAL DIAGNOSIS:
Juvenile idiopathic arthritis.
Reactive arthritis.
Hemophilia.
Psoriatic arthritis.
Septic arthritis.
DIAGNOSIS:
Juvenile idiopathic arthritis.
Types of the disease:
Oligoarthritis.
Polyarthritis.
PEARLS AND DISCUSSION:
Juvenile idiopathic arthritis is the most common rheumatological disease in children.
Age of presentation: below 16 years.
Female to male ratio is 2:1
It is idiopathic autoimmune process; however, genetic and environmental factors may influence the disease.
Types:
Oligoarthritis: It affects 1-4 to joints within 6 months of onset (most common subtype) classically involves the knees or ankles.
Polyarthritis: it involves > 5 joints within 6 months of onset.
Subtypes:
Rheumatoid factor positive: symmetric involvement of the small joints of the hands.
Rheumatoid factor negative: there is no characteristic pattern of joint involvement.
Radiology findings:
Plain radiograph
Early: Soft-tissue swelling, joint effusion, and periarticular osteopenia.
Late: generalized disuse osteopenia.
Erosion is uncommon usually at the sites of synovial reflection and ligament insertion (less overlying protective cartilage).
Joint space narrowing occurs due to thinning and gradual loss of the articular cartilage.
Advance disease may lead to ankylosis, growth disturbances, and joint malalignment.
In the hands, premature ossification of the carpal bones can result in a bone age greater than the chronologic age and early closure of the growth plate in the affected joint.
MRI
Contrast enhanced MR is the most sensitive modality to diagnose synovitis.
Assessment of articular cartilage, erosion and bone marrow edema.
Unresolved joint inflammation can result in irreversible cartilage degradation and destruction. It shows “spoke-wheel” pattern of enhancement may be seen in growing articular cartilage at MR imaging secondary to hyperemia caused by long-standing inflammation (resulting in epiphyseal overgrowth and chronic inflammation).
DIFFERENTIAL DIAGNOSIS:
JIA.
Reactive arthritis.
Hemophilia.
Psoriatic arthritis.
Septic arthritis.
Treatment:
The goal of JIA treatment is complete suppression of synovitis before the development of irreversible joint abnormalities.
It includes immobilization of the joint and NSAID.
FURTHER READING:
Elizabeth F. Sheybani, MD Geetika Khanna, MD et al. Imaging of Juvenile Idiopathic Arthritis: A Multimodality Approach. RadioGraphics 2013; 33:1253–1273
Sohaib Munir, Kedar Patil, Elka Miller et al. Juvenile Idiopathic Arthritis of the Axial Joints: A Systematic Review of the Diagnostic Accuracy and Predictive Value of Conventional MRI. American journal of Roentgenology January 2014, Volume 202, Number 1
Marcdante K, Kliegman RM. Nelson essentials of pediatrics. Saunders. ISBN: B00J
