Conventional Osteosarcoma, Distal Left Femur

18-year-old female with new onset distal right thigh pain. There is an infiltrative T1 hypointense, STIR hyperintense, heterogeneously enhancing mass centered within the distal right femoral diametaphysis with centrally necrotic components and a marked periosteal reaction. On the coronal T1 weighted images, the lesion is poorly circumscribed with infiltrative margins replacing the marrow fat of the distal right femoral diametaphysis. The fluid sensitive sagittal images demonstrate no significant perilesional edema. Conventional osteosarcoma was favored with a differential including Ewing sarcoma. On resection, a conventional osteosarcoma was found. Osteosarcomas are malignant bone forming tumors and are the second most common primary bone tumor after multiple myeloma. They occur in both primary and secondary forms. Primary osteosarcomas typically arise in young patients 10-20 years of age. Patients typically present with bone pain, with or without an associated soft tissue mass or swelling. MRI is used for local staging to assess intraosseous extent as well as soft tissue involvement. For metastatic disease assessment, noncontrast CT of the chest and/or nuclear medicine bone scan may be of value.