11-Year-Old Girl With Swollen Knees

October 15, 2014

Swelling and stiffness in both knees kept this preadolescent girl from the usual running and jumping. Xrays were normal. What do you make of the MRI images?

An 11-year-old female presents with persistent chronic swelling of the [[{"type":"media","view_mode":"media_crop","fid":"28493","attributes":{"alt":"pigmented villonodular synovitis","class":"media-image media-image-right","height":"150","id":"media_crop_1048771185061","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"2891","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"float: right; margin: 3px;","title":" ","typeof":"foaf:Image","width":"139"}}]]knees (right greater than left) and stiffness limiting mobility. Knee radiographs are unremarkable.

Representative images from bilateral knee MRI were obtained.

(Click on the image to enlarge.)

What's your diagnosis? Click here for the case report and discussion.

Answer: Pigmented villonodular synovitis (PVNS)[[{"type":"media","view_mode":"media_crop","fid":"28200","attributes":{"alt":"pigmented villonodular synovitis","class":"media-image media-image-right","id":"media_crop_4891228056616","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"2892","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"float: right; width: 146px; height: 211px; margin: 3px;","title":" ","typeof":"foaf:Image"}}]]

Comment

The MRI findings demonstrate diffuse nodular synovial thickening with extensive blooming artifact on gradient echo images and heterogeneous enhancement, in keeping with pigmented villonodular synovitis.  Synovial biopsy results confirmed the diagnosis. Despite recurrent synovectomy attempts, the nodular masses continued to persist and radiation therapy was pursued.

Related content on Rheumatology  Network, with longer discussion of PVNS:
Pigmented Villonodular Synovitis by T. Prema Sudha Rao, MD and Tammy Rochelle Spring, MD

Discussion[[{"type":"media","view_mode":"media_crop","fid":"28201","attributes":{"alt":"pigmented villonodular synovitis","class":"media-image media-image-right","id":"media_crop_4826347280221","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"2893","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"float: right; width: 140px; height: 139px; margin: 3px;","title":" ","typeof":"foaf:Image"}}]]

Pigmented villonodular synovitis (PVNS) is a rare disorder of synovial proliferation, which can be seen from adolescents to middle-aged adults. PVNS may present as a localized nodular mass or as a diffuse process, usually in the knee. Key MRI findings include low T1/T2 synovial nodularity with “blooming” artifact seen on gradient-echo images on the basis of hemosiderin contents.

Optimal treatment includes marginal excision for localized PVNS or [[{"type":"media","view_mode":"media_crop","fid":"28202","attributes":{"alt":"pigmented villonodular synovitis","class":"media-image media-image-right","id":"media_crop_2202690000814","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"2894","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"width: 137px; height: 150px; margin: 3px; float: right;","title":"","typeof":"foaf:Image"}}]]synovectomy for diffuse PVNS. Patients with high risk of recurrence may consider adjuvant radiation therapy, with few expected complications.

(Adaptedfrom an image-based quiz on Diagnostic Imaging.)

 

Reference
Mendenhall WM, Mendenhall CM, Reith JD, Scarborough MT, Gibbs CP, Mendenhall NP.  Pigmented Villonodular Synovitis. Am J Clin Oncol. (2006) 29:548–550.