Presentation
Painful left ankle post fall. Fracture?
Patient Data
No fracture. Pressure erosion at the anterior distal tibial plafond with adjacent soft tissue density.
Anterior ankle soft tissue mass with pressure erosion of the anterior distal tibial plafond.
Increased soft tissue density at the anterior ankle with increased pressure erosion at the anterior distal tibial plafond.
Centered in the anterior ankle joint there is an enhancing intra-articular mass which is homogeneously low T1 signal, low T2 signal with regions of susceptibility artefact. There is extension through the medial and lateral gutters into the posterior ankle joint. Evidence of pressure erosion most markedly at the anterior tibial plafond. No bone marrow edema/osteitis.
Case Discussion
Typical appearances of a diffuse intra-articular tenosynovial giant cell tumor, previously (and still commonly) known as pigmented villonodular synovitis (PVNS).
The findings on the first x-ray and CT were not seen prospectively - it is easy to miss unexpected pathology when an anchoring bias of history of trauma and question of fracture is provided.