[11-year-old male patient with bone lesion in distal left tibia.] [There is a well-defined eccentrically positioned lesion within the lateral aspect of the left distal tibial metaphysis. The lesion appears multiloculated with predominantly low T1 signal though with areas of high T1 signal suggesting blood products. The lesion is heterogeneously hyperintense on T2-weighted images with multiple fluid-fluid levels. Edema type signal is also noted within the bone surrounding the lesion and extending up the diaphysis. There is nodular and septal enhancement of the lesion following contrast administration. The superior and lateral metaphyseal cortex surrounding the lesion is indistinct, appearing similar to the prior radiograph. Furthermore there is circumferential abnormal T2 signal surrounding the metaphysis with enhancement of these soft tissues on postcontrast imaging. The lesion extends up to, but not across the distal tibial physis. Bone marrow signal within the distal left tibial epiphysis and left fibula are within normal limits. The remaining visualized soft tissue structures are unremarkable.
[Enhancing lesion within the distal tibial metaphysis with fluid-fluid levels, cortical erosion, and surrounding soft tissue enhancement; these findings are concerning for a primary bone sarcoma, particularly a telangiectatic osteosarcoma. A benign, but aggressive aneurysmal bone cyst is considered less likely given surrounding soft tissue findings. 