Reasons why a second radiological opinion is advisable: a case report of a misreported crural synovial cell sarcoma

Synovial sarcoma (SS) is a rare condition that accounts for 5–10% of all soft-tissue sarcomas (STS). SS locates most frequently near the joints, in particular at the lower extremities, but it can also occur in other locations. We report a case of a 42-year-old male complaining of a slow-growth mass on his right thigh, reported as a femoral nerve shwannoma on the basis of the preoperative radiological investigations, which revealed to be a monophasic SS on the histological examination. During the surgical procedure, the assistance of vascular surgeons was required to reconstruct the wall of the femoral vein underlying the tumor, that was pathologically thickened, and communicated with the tumoral capsule. Although extremely rare, SS should be considered in the differential diagnosis of peripheral nerve sheath tumors, in particular if next to a large vein at the lower extremities.