A1 - The most likely diagnosis is primary synovial chondroma | Figure 1

Pomeranz

Radiology

Diagnosis

A1 - Primary synovial chondromatosis

Synovial chondromatosis is a rare monoarticular process characterized by cartilaginous bodies. Primary synovial chondromatosis has a predilection for the large joints, including the knee, hip, elbow, and shoulder, although it can be identified in any joint or tendon. It affects males more frequently than females, and it is most common in the third to fifth decades. The MRI signal characteristics of the intraarticular bodies varies depending on the amount of calcification and/or ossification (images 5 and 6, arrows). Rarely, primary synovial chondromatosis can undergo malignant degeneration.

A2 - Secondary synovial chondromatosis

Secondary synovial chondromatosis is more common than primary synovial chondromatosis. It usually presents in the setting of longstanding osteoarthritis. In this patient, note that the medial and lateral compartments of the joint space are preserved. Only a small marginal erosion of the medial tibial plateau is noted (image 4, green arrow). Secondary synovial chondromatosis does not undergo malignant degeneration.

Similar Cases

Sagittal PD FS MR image in the same patient shows an osteochondral lesion (osteochondritis dissecans or OCD) of the mid capitellum. This is the donor site for the osteochondral body visualized in the olecranon fossa on the prior image. The intra-articular body on the prior image is likely larger than this donor site due to nourishment of the fragment by the synovial fluid. These fragments can become synovialized and hidden from the arthroscopist at surgery. Capitellar OCD classically occurs in little league pitchers due to the repetitive valgus stresses of overhead throwing.

A1 – Primary synovial chondromatosis. A2 – Differential diagnosis includes secondary synovial chondromatosis as a manifestation of osteoarthritis; donated chondral bodies from osteochondral defects; osseous bodies; and synovial hyperplasia. Secondary synovial chondromatosis is usually associated with osteoarthritis. It is important to distinguish primary from secondary synovial chondromatosis as the primary form can be associated with malignant degeneration while the secondary form has no association with increased incidence of malignancy.

A1 - (d) Synovial cyst Synovial cysts are associated with arthropathic facet joints, and rise near the joint articulation. They are most common in the lumbar region but can occur in cervical occasionally and thoracic rarely. L4-5 and L3-4 are the most common sites. Percutaneous drainage has a high recurrence rate. Surgical resection is usually required. Synovial cysts often contribute to compressive radiculopathy.

AP, oblique, and lateral radiographs of the foot in a patient with pain insensitivity show destruction of the medial cuneiform and dorsal and distal talus consistent with a Charcot or neuropathic joint. Radiographs can show destructive changes of the joint with bone fragmentation and debris. They most commonly affect the foot and ankle.