Musculoskeletal #29

30-year-old male:

· Persistent pain in his right ankle, for a year long, a synovial mass was demonstrated on ultrasound. · Ankle MRI was performed

What do you see?

Pigmented villonodular synovitis (diffuse articular form)

* Benign proliferative condition affecting the synovial membrane. Most commonly monoarticular
* MRI: Mass-like synovial proliferation with lobulated margins and articular erosions
– Signal -> T1: low-intermediate ; DPFS/STIR: heterogeneous with areas of high signal ; GE: blooming artifact ; T1GD: variable enhancement.

What is the differential diagnosis?

Differential diagnosis includes:
* Scarring – capsulitis
* Siderotic synovitis
* Synovial sarcoma