Presentation
Left calf swelling, for assessment.
Patient Data
Large complex cystic soft tissue mass involving the posterior medial aspect of the leg. The lesion demonstrates mixed high and intermediate signal intensity on T2 and a central hemorrhagic component of high T1 images. Intralesional fluid-fluid levels are seen giving the appearance of "bowl of grapes". The mass is located at the expected location of pes anserinus bursa. There is no bony or joint extension.
The differential diagnosis would include synovial sarcoma or angiomatoid fibrous histiocytoma (pleomorphic undifferentiated sarcoma).
Case Discussion
MRI features of synovial sarcoma are of a well-defined heterogeneous soft tissue mass around joint, more specifically, near to the tendon, bursa or around the joint capsule. The "triple sign" is classically described in synovial sarcoma which is a mixture of high, intermediate and low signal regions within the mass seen on T2 weighted images. Another helpful sign is "bowl of grapes", which describes the appearance of multiple fluid-fluid levels in the mass. Bony erosions or secondary joint space invasion can occur 1.
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