Fig. 2.

Presentation at 5 month mark:

(A, B) AP and lateral plain radiographs showing cortical erosion, soft tissue extension and minimally displaced pathological fracture (arrow); (C) Coronal STIR weighted MR image showing cortical destruction and medullary soft tissue expansion with associated internal fluid-fluid level (arrow); (D) Thallium scan demonstrates peripheral thallium avidity within the proximal right tibia; (E) Open biopsy showing mulitnucleated giant cells (red arrow) together with smaller mononuclear cells, haemorrhage, fibrin and granulation tissue. Also an area of fibrous stroma is seen (green arrow). These features are consistent with aneurysmal bone cyst in the setting of fibrous dysplasia.