Synovial chondromatosis is an uncommon, usually monoarticular condition that is characterized by chondrometaplasia of the synovial membrane and the formation of highly cellular cartilagenous nodules.1,2 These nodules of proliferative cartilage may remain attached to the synovial membrane or dislodge into the joint space to form "loose bodies." Synovial chondromatosis may progress through 3 distinct histopathologic phases: (1) metaplasia within the synovial membrane without detached nodules in the joint space; (2) coexistence of active chondrometaplasia within the synovium and detached cartilaginous nodules in the joint space; and (3) presence of numerous loose bodies within the joint space in the absence of active chondrometaplasia of the synovial membrane.1 Although synovial chondromatosis may occur as a result of trauma or infection, the cause is unknown in many cases.
Quiz Case 4. Arch Otolaryngol Head Neck Surg. 2000;126(7):903-908. doi: