Primary Synovial Chondromatosis

Primary synovial chondromatosis is a benign neoplastic process that typically affects adult men in their 20s to 40s, with the knee being the most commonly affected site. It is characterized by hyaline cartilage nodules of variable calcification in the subsynovial tissue of a joint, tendon sheath, or bursa, which may break off from the synovial surface into the joint.

Radiographs and CT reveal multiple intraarticular chondral bodies and extrinsic, well-marginated erosion of bone on both sides of the joint. The chondral bodies are usually of similar size and demonstrate variable calcification, ranging from tiny speckles to large, round, and lamellated. MRI findings are variable due to the variable calcification of these chondral bodies. However, erosions are seen in 80% of patients on MR. Post-contrast imaging reveals hyperplastic, enhancing synovium.

The extraarticular form typically affects the hands or feet, where there are calcifications in tendon sheaths or bursae with or without saucerization of adjacent bone.

Differential considerations include:

• Intraarticular or juxtacortical chondroma
• Synovial chondrosarcoma
• Pigmented villonodular synovitis
• Secondary synovial osteochondromatosis

References

Murphey MD, et al. From the Archives of the AFIP: Imaging of Synovial Chondromatosis with Radiologic-Pathologic Correlation. RadioGraphics 2007 27:1465-1488.