MSK for Thursday, April 10th, 2025
Contributed by
The Queensland Children's Hospital
Kieran Frawley.
History
10 year old with knee swelling.
Images (Click any image to enlarge)
Horizontal beam lateral xray
Sagittal T2 fat sat
Coronal T2 fat sat
Axial T1
Axial gradient echo.
Axial post contrast T1
Sagittal T1
Question
What is the cause of the knee swelling?
Your answer
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Correct answer
Suprapatellar vascular malformation.
Discussion
Diagnosis is a vascular malformation. Subtle fluid fluid levels on the axial gradient echo and post contrast images. This is potentially walled off by a superior synovial plica as it appears confined to the suprapatellar pouch. There was mild synovitis but no substantial arthropathy.
Differential diagnosis
Pigmented villonodular synovitis.
No calcification to suggest synovial osteochondromatosis.
Additional images
Ultrasound image shows partially compressible fluid with septations in the suprapatellar pouch.
References
- Jans, L., Ditchfield, M., Jaremko, J.L. et al. MRI demonstrates the extension of juxta-articular venous malformation of the knee and correlates with joint changes. Eur Radiol 20, 1792–1798 (2010). https://doi.org/10.1007/s00330-010-1733-7