Figure 7.

Aneurysmal bone cyst (stage 3) in an 18-year-old male. (A) X-ray appearance showing a large lytic lesion involving the proximal and middle foot. (B) Sagittal T1-weighted MRI shows deformity in the involved bone with a multiseptated lesion; (C) MRI T2-STIR in axial projection shows the typical fluid-fluid levels (white asterisk). (D) Histological view of the cellular septa containing fibroblasts, giant cells, and woven bone. There are typical cavernous spaces filled with blood, lacking endothelial lining.