Presentation
Two months of pain and mild swelling of the distal femur
Patient Data
On the scanogram, there is a permeative lytic lesion at the medial meta-diaphysis of the femur with some soft tissue swelling medially. Periosteal reaction forms the Codman triangle. No calcification or ossification was identified.
CT demonstrates a soft tissue mass replacing the marrow of the distal diaphysis and the metaphysis of right femur. There is cortical destruction medially and anteriorly with extension of this mass into the medial soft tissues elevating the overlying muscles. There are ill-defined areas of mineralization in this soft tissue mass within the medullary canal and within the extraosseous component. No extension into the epiphysis is seen.
The knee joint is unremarkable. There is no skip lesion.
Case Discussion
Based on imaging, the most likely diagnosis was felt to be osteosarcoma with a differential of Ewing sarcoma.
The diagnosis was proven to be osteosarcoma on histopathology.
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