Prominent heterogeneity with predominant high signal intensity is also a feature of these lesions on T2-weighted MR images
This signal heterogeneity has been described as the triple sign by Jones and co-workers,
represented by intermixed areas of low,
intermediate,
and high signal intensity on long repetition time images).
This marked heterogeneity and triple sign on T2-weighted MR images is presumably the result of the mixture of solid cellular elements (intermediate signal intensity),
hemorrhage or necrosis (high signal intensity),
and calcified or fibrotic collagenized regions (low signal intensity).
The triple sign has been described as occurring in 30 percent of synovial sarcomas.
the pathologic diagnosis is based on the histologic exam with the aid of special staining techniques.
Vimentin stains intermediate filaments and is typically positive in synovial sarcoma.
BCL-2 is an apoptosis gene and is positive in many neoplasms.
EMA and Cytokeratin 5/6 are epithelial markers and are usually positive in synovial sarcoma.
S-100 is a marker of neural differentiation and can be positive or negative in synovial sarcoma.on for the lower extremity.
Monophasic fibrous synovial sarcoma (SS) is the most common variant of SS.
Only a few cytological studies are available on this entity.
Bcl-2 protein expression has been described as a characteristic marker of SS and is useful for its differentiation from other sarcomas.
Cytokeratin and CD99 are also used in detecting SS.
Synovial sarcomas have two main histologic types,
monophasic fibrous and biphasic.
The monophasic type has a fibrous appearance on the histologic exam with spindle-shaped cells and is commonly positive for S-100.
The biphasic type is composed of more cuboidal or columnar epithelial cells and is usually negative for S-100
MRI is useful for evaluating the extent of the tumor and its involvement with adjacent soft-tissue structures.
For instance,
MRI is helpful in the differentiation of tumor from muscle tissue and in depicting the involvement of neurovascular structures,
tendons,
fascial/fat planes,
and bone marrow.
MRI is also helpful for the differentiation of recurrent soft-tissue tumors from postsurgical or post-irradiation changes.