SYNOVIAL CHONDROMATOSIS AND CHONDROSARCOM A - RELATIONSHIP BETWEEN THESE 2 DISEASES

Purpose of the study This retrospective study concerns six patients in whom chondrosarcoma was suspected to develop in synovial chondromatos is. We discuss for these cases different diagnosis. The authors expose the clinical signs and radiological aspects which suggest malignant t ransformation. We report the indispensable criteria for established di agnosis of malignant transformation of synovial chondromatosis and app ropriated forms of therapeutic management were suggested. Materials an d methods Six patients, 3 males and 3 females from 36 to 58 years of a ge were included in this study. Three patients presented 6 months, 3 y ears and 25 years history of synovial chondromatosis of the knee joint . When the malignant transformation appeared, a surgical biopsy was pe rformed and the pathologist diagnosed a chondrosarcoma in all cases. F or the other three patients, the chondrosarcoma and synovial chondroma tosis were diagnosed at the same time. The localization was shoulder, hip and knee. A surgical biopsy was performed and the pathologist diag nosed chondrosarcoma. Synovial chondromatosis was diagnosed by histolo gic examination of the resection or amputation specimen. Treatment and results Four patients had thigh amputation, one patient had ''en bloc resection'' of the hip-joint and the last patient had resection of th e shoulder joint. In all cases, the histologic examination diagnosed c hondrosarcoma and synovial chondromatosis. All patients were free of d isease. Discussion The malignant transformation of synovial chondromat osis is rare but this diagnosis must be established to perform appropr iate treatment. Other possible diagnosis are : - low grade synovial ch ondrosarcoma initially diagnosed as a synovial chondromatosis. Bertoni believes that all cases of malignant transformation of synovial chond romatosis are initially low grade chondrosarcoma. We believe that his criteria are too strict for diagnosed chondrosarcoma. - coexistence of synovial chondromatosis and synovial chondrosarcoma. These 2 diagnosi s are extremely rare and their coexistence are unlikely. - secondary s ynovial chondromatosis developed into chondrosarcoma. We don't have hi stologic criteria to confirm this diagnosis in all our cases. The symp toms that should suggest a malignant transformation of synovial chondr omatosis were: - rapid late deterioration of clinical conditions, - bo ne invasion diagnosed by X-ray films and medullar invasion discovered by MRI. According to us, the indispensable criteria to diagnose malign ant transformation were: 1 degrees) histologic diagnosis of synovial c hondromatosis established before diagnosis of chondrosarcoma, 2 degree s) histologic diagnosis of chondrosarcoma on the same anatomic site as the synovial chondromatosis, 3 degrees) diagnosis of chondrosarcoma a nd synovial chondromatosis on the same resection specimen. Only the th ree first cases were in accordance with these criteria. The treatment must be a ''en bloc resection'' of the joint or an amputation. Conclus ion Malignant transformation is rare, but this diagnosis should be est ablished to perform adequat treatment, This diagnosis should be suspec ted when a rapid deterioration of the clinical status appeared and whe n bone involvement was detected by MRI. However, the danger still lies in the misinterpretation of the synovial chondromatosis as chondrosar coma. This diagnosis can be made with clinical, radiological and patho logical criteria. The treatment must be a wide resection or an amputat ion.