Synovial sarcoma with lung metastases

Case contributed by Yune Kwong


Knee pain

Patient Data

Age: 20-25 years
Gender: Male

Soft tissue mass within medial suprapatellar pouch with foci of calcification (best seen on lateral).

MRI confirms a mass in the medial suprapatellar pouch. It has heterogenous signal pre-contrast and enhances heterogenously post-gadolinium.

Short of breath 2 years later.


Complete 'white-out' of the left chest with marked mediastinal deviation to the right. Multiple masses in the right lower lobe, better seen on the lateral. From the CXR, it was unclear if the left chest opacity is due to effusion or masses.

CT shows huge soft tissue mass occupying the whole of the left chest, causing impressive contra-lateral displacement of the heart. No significant effusion on this non-contrast scan. Multiple other metastases on the right lung.

Case Discussion

Biopsy of the intra-articular knee lesion showed synovial sarcoma. The finding of a soft tissue mass with calcification close to a joint in a young patient should strongly suggest this diagnosis. 5-10% are intra-articular. Pigmented villonodular synovitis (PVNS) was considered in the differential in this case, but this is not correct as PVNS does not calcify.

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