Focal uptake of Tc-99m MDP in soft tissues has been described, usually in areas of dystrophic calcification. Osteosarcoma, a childhood bone tumor, directly forms osteoid, both in the primary and metastatic lesions. Tc- 99m MDP is incorporated in tumor osteoid on delayed images and is seen as areas of increased uptake. Although extraosseous activity in metastatic deposits has been reported, this unusual case demonstrates an osteosarcoma with pericardial metastases seen on Tc-99m bone scan and confirmed by CT.
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