Tumor Thrombus Associated With Locally Recurrent Osteosarcoma on [18F] FDG PET/CT

Tumor thrombus arising from osteosarcoma is rare, with only a few cases documented in the literature. Herein, we report a case of locally recurrent osteosarcoma complicated by tumor thrombus in a patient who had undergone prior neoadjuvant chemotherapy, surgical resection, and rotationplasty for a distal left femoral osteosarcoma. An [18F] FDG PET/CT scan revealed an FDG-avid locally recurrent tumor in the soft tissues of the left thigh contiguous with FDG-avid tumor thrombus extending from the mid-left femoral vein to the left external iliac vein. This case illustrates that, although rare, osteosarcoma can cause tumor thrombus, and [18F] FDG PET/CT can be a useful diagnostic tool in such cases.