Synovial neoformations and tumours.

An important group of soft tissue tumours and tumour-like lesions originates from the synovium of the joints, bursae and tendon sheaths. These include synovial chondromatosis, diffuse articular lipomatosis (lipoma arborescens), villonodular synovitis, synovial haemangioma, synovial chondroma and fibroma (intracapsular and peri-articular), primary chondrosarcoma originating from the synovium and synovial sarcoma. The main clinical symptoms of these tumours, such as pain, swelling, effusion and joint locking, are not specific, so the diagnosis can easily be missed in clinical practice. The most important clinical characteristics and the differential diagnostic clues for synovial tumours and tumour-like lesions are described in this chapter. In addition, the new results of genetic and histological studies are discussed, together with a summary of the available evidence-base for therapy.