Synovial chondromatosis of the hip: a case report and clinicopathologic study

Primary synovial chondromatosis (PSC) is a rare, usually monoarticular disorder of synovial joints. PSC is characterised by the formation of osteocartilaginous nodules in the synovial connective tissue. We report the case of a 32-year-old male with PSC of the left hip. At clinical examination abduction of the left hip was limited and rotation was painful. Ultrasound examination of the hip revealed joint effusion and multiple hyperechogenic foci due to distal acoustic shadowing. Plain radiographs showed a slight soft tissue swelling around the femoral neck and multiple round or ovoid calcifications of a uniform size. MRI revealed a large joint effusion with multiple small filling defects. Open total synovectomy was performed after dislocation of the femoral head. The diagnosis of PSC was confirmed by histological examination of the excised material. The majority of cells failed to exhibit any staining for cerb B-2 and ki-67. None of the sections showed more than 5% labelling for DNA-fragmentation proven by terminal deoxytransferase-mediated dUTD nick-end labeling (TUNEL), and all were completely non-reactive for p53 as well. In conclusion, immunohistochemical analysis suggests that in this case PSC originated from metaplasia and not from a proliferative process. After two years, the patient was free of symptoms and radiological control did not show evidence of recurrence or femoral head necrosis. Physical findings, diagnosis, histological features and management of PSC are discussed.