A 46-year-old male with right flank pain after a fall was diagnosed with monophasic synovial sarcoma after surgery. Despite radical nephrectomy, wide local excision, and radiotherapy, the tumor recurred. Further resection with right hemicolectomy, followed by chemotherapy, resulted in complete remission at 26 months. This case highlights the diagnostic challenge of synovial sarcoma, which can mimic a hematoma, and the importance of a multidisciplinary approach for effective management and successful outcomes.