Synovial chondromatosis is a benign condition characterized by synovial proliferation and metaplasia, with development of cartilaginous or osteocartilaginous nodules within a joint, bursa or tendon sheath.

The differential diagnosis of primary synovial chondromatosis includes:

• pigmented villonodular synovitis (PVNS)
  • more confluent masses
  • diffuse characteristic low intensity on MRI
• synovial hemangioma
• lipoma arborescens
  • characteristic fat signal/density
• synovial chondrosarcoma
  • soft tissue mass
  • extension beyond the joint
  • presence of metastases
• siderotic synovitis