Extra-articular Extra-synovial Solitary Osteochondromatosis of the Ankle

ABSTRACT Synovial chondromatosis or osteochondromatosis is a benign neoplastic condition arising from synovial tissue of joints, tendon sheath and bursa. The commonly involved joints are the knee, hip, shoulder, elbow and ankle. According to the author's knowledge, only four cases have been reported in the English literature, describing the extra-articular synovial chondro-matosis around the ankle joint. The peculiarity of the index case lies in its subtle clinical and radiological presentations which can create a diagnostic dilemma.