• Journal of the Korean Arthroscopy Society
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• v.13 no.3
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• pp.272-275
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• 2009

Extraarticular synovial chondromatosis is a very rare disease which affects the hands, feet, and wrists most commonly. In cases of involvement around large joints, the tissues around knee are usually involved. It arises from tendon sheath, capsular tissue and bursae. It is an idiopathic process in which the synovial cells undergo the metaplasia into cartilage cells. Chondroid matrix of the cartilaginous nodules calcify and ossify to be the osteochondroma. On simple radiograms before calcification and/or ossification of the chondroid tissues the cartilaginous nodules look normal on radiograms. Therefore MRI is needed to establish the diagnosis. We report a case of extraarticular pan-peri-meniscal synovial chondroma around right knee, initially suspected as a ganglion cyst which clinically mimicked a large rounded lesion or a cystic lesion on MRI.