Presentation
Slowly growing painless swelling at the ankle region
Patient Data
A well-defined oval-shaped mass is seen anterior to the talus, extra articular in position and underneath the tendon of the extensor hallucis longus. The mass displays low signal on T1, lower signal on T2 likely from hemosiderine deposition, heterogeneous high signal on STIR, and avid enhancement on post contrast study with two foci of calcification seen within. No evidence of infiltration of the adjacent structures.
Case Discussion
Nodular tenosynovitis also known as a giant cell tumor of tendon sheath is a localized form of pigmented villondoular synovitis, usually extra articular in location and shows the same pathological changes. Differential diagnoses include synovial sarcoma (usually bright signal on T2 and shows infiltrative edge), hemophilia and fibromatosis. Post excision, the histopathology revealed xanthoma cells and hemosiderin laden macrophages.