Uncommon synovial pathologies

The synovium is a specialized tissue lining the synovial joints, bursae, and tendon sheaths of the body. It is affected by various localized and systemic disorders. Synovial diseases can be broadly classified as inflammatory, infectious, degenerative, proliferative, hemorrhagic, and neoplastic. Injuries to other structures within the joint, such as cartilage, may also be caused by pathological processes that affect the synovium. Early detection of synovial diseases is critical to avoid irreversible joint damage. Understanding the typical imaging features of synovial diseases can help in accurate diagnosis and prompt treatment. Therefore, imaging plays a crucial role in detecting synovial diseases at an early stage. This pictorial review highlights the unusual synovial pathologies, such as synovial chondromatosis, pigmented villonodular synovitis (PVNS), giant cell tumor of tendon sheath (GCTT), hemophilic arthropathy, lipoma arborescens, and synovial sarcoma.