279 lnfrapatellar Pigmented Villonodular Synovitis: Arthrographic Detection Mitchell B. Lowenstein1 Jay R. V. Smith2 Solon Cole3 Received July 1 7, 1 979; accepted after revi- sion April 7, 1980. ‘Department of MedIcine, University of South Florida, and Mease Hospital and Clinic, Dunedin, FL 33528. Address reprint requests to M. B. Low- enstein at Mease Hospital. 2Department of Radlolo9y, Hartford Hospital, Hartford, CT 06115. 3Department of Patholo9y, Hartford Hospital, Hartford, CT06115. AJR 1 35:279-282, August 1980 0361 -803X/80/1 352-0279 $00.00 © American Roentgen Ray Society An ovoid density was demonstrated by arthrography In the infrapatellar fat pad region of seven patients. In three patients, the density appeared demarcated from the fat pad, and arthrotomy in two of them disclosed a localized pigmented villonodular synovitis. In four patients the density appeared contiguous with the fat pad, and in two of these patients no Infrapatellar abnormality was observed at arthrotomy. This arthro- graphic distinction may provide more specific criteria for the preoperative diagnosis of localized, infrapatellar pigmented villonodular synovitis and thereby prevent overdi- agnosis. Pigmented villonodular synovitis (PVS) is a benign histiocytosis of the lining of joints, tendon sheaths, and bursae. Involvement within joints may be localized or diffuse. Localized disease may be at any site in the joint. Disability in the diffuse form results from pain, swelling, locking [1 ], and erosion of cartilage and bone [2-5]. In localized PVS, symptoms are similar but less severe [6]. The arthrographic diagnosis of both generalized [7] and localized [8] PVS have been described. Localized infrapatellar PVS causes an arthrographic abnormality in the region of the infrapatellar fat pad [8]. Other lesions such as fat pad or localized synovial hypertrophy [9], intraarticular ganglion [1 0], uncalcified intraar- ticular bodies [1 1 ], and intraarticular tumors [1 2] produce similar arthrographic defects. We describe the arthrographic appearance of localized PVS in the region of the infrapatellar fat pad. We also present a similar but distinguishable arthro- graphic abnormality in cases where a lesion of the infrapatellar region was not found at arthrography. Materials and Methods Double-contrast knee arthrography [1 3] was performed on 1 629 knees (1 61 4 patients) during 1 975 through 1 977. Nodular defects in the region of the infrapatellar fat pad were observed in seven knees in seven patients, four male and three female, aged 1 6-57 years (mean, 23.4). The clinical history was obtained by chart review. In no case was arthrocen- tesis or arthroscopy performed. Pathologic specimens obtained at arthrotomy were avail- able in four of seven cases. They were studied grossly and microscopically stained with hematoxylin and eosin. The other three patients were not surgically treated (table 1). Downloaded from www.ajronline.org by 34.228.24.229 on 05/30/20 from IP address 34.228.24.229. Copyright ARRS. For personal use only; all rights reserved