Radiological features are in favor of pigmented villonodular synovitis of the ankle joint and giant cell tumor of the flexor hallucis longus tendon sheath.

Editor's note: Per the 2020 WHO Soft Tissue and Bone Tumors Classification (5th ed.), the recommended terminology is tenosynovial giant cell tumor with pigmented villonodular synovitis no longer recommended (although remains in common use).