Synovial hemangioma of the knee joint--a case report.

At arthroscopy, a 22-year-old woman with repeated spontaneous hemarthrosis of the knee was found to have a synovial hemangioma, which was removed by arthrotomy. In cases of spontaneous hemarthrosis without abnormal bleeding tendency, arthroscopy is recommended to identify and, if possible, treat the cause of bleeding, as repeated bleedings may damage the joint.