Idiopathic synovial chondromatosis in two unusual sites: inferior radioulnar joint and ischial bursa

Synovial chondromatosis is a rare disorder of unknown cause characterized by multiple calcific bodies in the vicinity of the affected joint. It is most commonly seen in the knee, hip, elbow, and shoulder. We describe three cases of synovial chondromatosis in two extremely uncommon sites, the inferior radioulnar joint and the ischial bursa, and review the literature on the subject. The characteristic radiographic appearance, even if in an uncommon location, should prompt the radiologist to suggest the correct diagnosis preoperatively.