Anterior abdominal wall synovial sarcoma: a rare presentation.

Synovial sarcoma usually arises in the extremities and in close proximity to large joints. Primary synovial sarcoma of the anterior abdominal wall is rare. A 17-year-old girl was admitted to the hospital with a palpable abdominal mass, and there was a 9.5 cm x 7.5 cm x 6-cm lobulated, cystic, and semisolid lesion of in the external oblique abdominal muscle shown on the abdominal magnetic resonance image. She was then operated and pathology was consistent with synovial sarcoma. The presence of synovial sarcoma in extraarticular sites such as the abdominal wall argues against an origin from arthrogenous mesenchyme.