Presentation
Pain and swelling at the medial and lateral ankle for several months. X-rays inconspicuous.
Patient Data
Intrasynovial well-defined soft tissue lesions are noted at the ankle joint with low signal intensity on T1 and T2 and heterogeneous postcontrast enhancement with associated underlying bone erosions notably in the body of talus in keeping with diffuse pigmented villonodular synovitis.
Flexor hallucis longus tendon shows a tenosynovial well-defined lesion with lobulated outline exhibiting same signal characteristics as the ankle joint lesions in keeping with tenosynovial giant cell tumour.
Case Discussion
Radiological features are in favour of pigmented villonodular synovitis of the ankle joint and giant cell tumour of the flexor hallucis longus tendon sheath.
Editor's note: Per the 2020 WHO Soft Tissue and Bone Tumours Classification (5th ed.), the recommended terminology is tenosynovial giant cell tumour with pigmented villonodular synovitis no longer recommended (although remains in common use).