PMC4486103_01
Initial presentation of right tibial diaphyseal lesion:. Radiolucent lesion with medullary expansion and endosteal scalloping shown in: (A) AP radiograph; (B) Coronal CT scan showing a well circumscribed lesion with endosteal scalloping; (C) Coronal T1 with fat saturation MRI; (D) Thallium scan showing moderate heterogeneous uptake in the right proximal tibia on delayed 4 h planar imaging; (E) Core biopsy showing spindle cell proliferation (red arrow) and fibrous stroma with immature bone formation (green arrow), consistent with fibrous dysplasia.
gr1.jpg
PMC4486103_01_gr1.jpg
fig0005
Imaging was consistent with fibrous dysplasia in the proximal tibia; the lesion measured 15 cm in length and demonstrated endosteal scalloping, ground-glass opacity and medullary expansion without periosteal reaction (Fig. 1). Core biopsy was performed under CT guidance targeting the area of thallium avidity, and pathology showed spindle cell proliferation and fibrous stroma with immature bone formation (Fig. 1).
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.
gr2.jpg
PMC4486103_01_gr2.jpg
fig0010
Plain radiographs showed cortical thinning associated with a pathological fracture of the anterior cortex of the tibia and an increase in lesion size (Fig. 2). Fluid-fluid levels were also noted (Fig. 2). This showed a cellular lesion with numerous mulitnucleated giant cells together with smaller mononuclear cells, haemorrhage, fibrin and granulation tissue (Fig. 2).
Presentation at 8 month mark:. (A, B) AP and lateral plain radiographs showing large radiolucent lesion with cortical erosion and soft tissue extension; (C) Coronal STIR weighted MR image demonstrates marrow replacement by soft tissue lesion with soft tissue extension; (D) Thallium scan demonstrates peripheral thallium avidity of the proximal right tibia on 4 h planar images; (E) Histology confirms aneurysmal bone cyst; (F) Clinical photo of resection specimen showing bony replacement and soft tissue expansion.
gr3.jpg
PMC4486103_01_gr3.jpg
fig0015
Repeat imaging showed extensive disease progression with increased lesion size, cortical destruction, soft tissue extension into all compartments of the leg and encapsulation of the neurovascular bundle (Fig. 3). Histology on the whole specimen confirmed extensive aneurysmal bone cyst in association with fibrous dysplasia extending into soft tissue, again with no features of malignancy (Fig. 3).