Intrapelvic Retroperitoneal Synovial Sarcoma in a 15-Year-Old Adolescent Girl: A Case Report and Review of the Literature.

Synovial sarcomas are a rare subtype of soft tissue sarcomas mostly located in the lower extremities. The authors report a case of synovial sarcoma in a 15-year-old adolescent girl with several unusual features including age, intrapelvic retroperitoneal location of the primary tumor, and presentation with right abdominal tenderness and compression of the iliac vessels with thrombosis of the right iliac and femoral vein.