Pigmented villonodular synovitis
 Discussion of Pigmented villonodular synovitis
- Pigmented Villonodular Synovitis (PVNS) is a benign proliferative disorder of the synovium that may affect the joints, bursae, or tendon sheaths.
- It can appear in either a diffuse or, less commonly, a focal form within the joint.
- PVNS most often occurs in young to middle-aged adults.
- The knee is the most frequently involved joint, followed by the hip, ankle, and shoulder.
- Polyarticular involvement is extremely rare.
- Local recurrence following surgical or arthroscopic synovectomy occurs in almost 50% of case.
 Imaging Findings for Pigmented villonodular synovitis
- Conventional radiographs of joints affected by PVNS may appear normal or may demonstrate periarticular soft-tissue swelling. Joint spaces and bone mineralization are characteristically preserved until late in the disease. Bone erosions are common in joints with a tight capsule, such as the hip and ankle.
- On MR images, the masslike proliferative synovium has a lobulated margin, and it may be extensive in diffuse PVNS or limited to a single nodule in the focal form.
- The lesions tend to bleed, causing hemosiderin deposition and a characteristic blooming on gradient echo imaging.
- Areas of high signal intensity on T2-weighted images may be present and are likely caused by inflamed synovium or joint effusions.
Patient #1: MR images demonstrate PVNS
Patient #2: Right shoulder radiographs demonstrate erosions from PVNS
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 References for Pigmented villonodular synovitis
- Patrick J. Sheldon, Deborah M. Forrester, and Thomas J. Learch. Imaging of Intraarticular Masses. RadioGraphics 2005 25: 105-119.