Unresectable retrovesical synovial sarcoma treated by chemotherapy and radiotherapy: A rare case report

Background: Synovial sarcoma is a rare type of soft tissue sarcoma.It usually arises from areas where synovial tissue exists and can be found in almost any part of the body, especially at the extremities.Retrovesicall synovial sarcoma is a very rare tumor and represents about 1% of retrovesical tumors.Clinical case: we report a case of a 55-year-old woman, hospitalized for acute urinary retention.Imaging of the pelvis showed a right-lateralized retrovescical mass, measuring 140x130x116 mm exerting mass effect on the bladder and the rectum.Transrectal biopsy showed a poorly differentiated tumor.Immunohistology was positive for Pancytokeratin, CD99, and BCL2, and negative for CDX2, Desmine, myogenine, and CD117, concluding to the diagnosis of synovial sarcoma.A neoadjuvant chemotherapy followed by exclusive radiotherapy was performed with good clinical response.6 months after treatment, patient still free of recurrence.Conclusion: Retrovesical synovial sarcoma is very rare and its management is controversial.Surgery remains the mainstay of treatment whenever possible.In case of unresectable disease, neoadjuvant chemotherapy and radiotherapy can be used with good outcomes.