Synovial osteochondromatosis of the distal radio-ulnar joint.

Synovial osteochondromatosis is an uncommon lesion characterized by cartilagenous and osseous metaplasia of joint synovium. It is typically monarticular, affecting large joints such as the knee and hip, although it has also been described in the ankle, elbow and shoulder. It is exceptionally rare in the hand, but has been reported involving the tenosynovium of the digits and the wrist. We report a rare case of synovial osteochondromatosis involving the distal radio-ulnar joint in a 16-year-old man.