| Discussion: |
Synovial osteochondromatosis (SOC) is a benign condition characterized by synovial membrane proliferation and metaplasia. The entity also is termed synovial chondromatosis. The synovial lining of a joint, bursa, or tendon sheath undergoes nodular proliferation, and fragments may break off from the synovial surface into the joint. In this location and nourished by synovial fluid, the fragments may grow, calcify, or ossify. The intra-articular fragment may vary in size from a few millimeters to a few centimeters.
The degree of calcification varies, and calcification may be seen as a few calcific specks or as foci of frankly ossified bodies. The fragments may be found free within the joint cavity, or they may be embedded within the proliferating synovium, which may extend into the surrounding soft tissues. The natural history of SOC entails gradual progression of disease, joint deterioration, and secondary osteoarthritis. Essentially, the disease is a benign process, and although recent studies in the literature have reported malignant transformation, this finding is decidedly unusual.