As you probably know by now, synovial sarcoma is a malignant soft-tissue tumor that occurs most often in the extremities (arms and legs). A regular X-ray will not show soft tissue malignancies. It was unusual that the more advanced imaging (MRI) did not at least show some change in intensity to indicate a mass of this type.
MRI with contrast is not typically the next step in diagnosis when there has been no indication of a problem. It is a more expensive test and exposes the patient to a type of dye that is injected into the bloodstream just before (or sometimes during) the procedure. Certain abnormalities, such as tumors, will absorb the dye and show up very clearly on the MRI with contrast.
There have been reported cases where repeated MRIs did NOT reveal a malignant soft-tissue tumor later diagnosed as synovial sarcoma. As a result, an accurate diagnosis and appropriate treatment were delayed by a full year for the patients in question. This has led to a recent recommendation for physicians to consider synovial sarcoma when a patient presents with what looks like turf toe but has unusual patient history and lack of response to treatment.
Synovial sarcomas are rare but occur most often in young, healthy adults. They are often overlooked and/or mistaken for other problems. There have been 26 other cases reported of synovial sarcoma of the forefoot, so it is rare but may occur more often than anyone previously realized.