Primary monophasic synovial sarcoma presenting as a benign neurogenic tumor: case review and review of the literature.

This report describes two cases of monophasic synovial sarcoma which were initially diagnosed as benign nerve sheath tumors based on imaging features. Retrospective review of the first case and re-review of the second case after initial diagnosis showed imaging features which distinguished the lesions from classical, benign neurogenic tumors. Accurate prospective diagnosis of soft tissue masses in locations in or around nerves and with morphology similar to nerve sheath tumors represent a clinical challenge. Careful review of imaging features and absence of the typical, reproducible findings should allow the benign lesion to be excluded from the diagnostic possibilities in most cases and allow for improved preoperative planning.