Synovial sarcoma - knee

Case contributed by Ammar Haouimi
Diagnosis almost certain


Progressive painless swelling of the anterolateral aspect of the left knee.

Patient Data

Age: 20 years
Gender: Female

The MRI sequences demonstrate a relatively well-defined prepatellar soft tissue mass at the inferolateral aspect of the patella, of intermediate signal intensity on T1WI, high signal intensity on PD fat sat with a central area of low signal. The postcontrast sequences show a heterogeneous enhancement mainly peripheral with restricted diffusion on DWI/ADC. This lesion encases partially the lateral portion of the patellar tendon and lateral retinaculum with mild retro and infrapatellar extension. Menisci and ligaments are intact. No significant joint effusion.

Case Discussion

Case of synovial sarcoma (histologically proven).

Synovial sarcomas are of intermediate-to-high grade malignant soft tissue tumors, affecting mainly young patients, most commonly seen around the knees.

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