A 20-year-old male presented with pain in the right shoulder region which aggravated with activity. On examination, a mass was felt in the right shoulder region which was warm and tender, had increased surface vascularity and a bruit was discernable over the mass. There was decreased range of motion of the right shoulder joint. X-ray of the concerned area was done. Radionuclide scan was also carried out. The tumour was resected and sent for HPE examination. Which is the most likely diagnosis in the above scenario: -

This is a case of osteosarcoma. 1ST image shows impressive swelling throughout the deltoid region, as well as the disuse atrophy of the pectoral musculature. Radiographic appearance of a proximal humeral osteosarcoma with the radiodense matrix of the intramedullary poion of the lesion, as well as the soft-tissue extension and aggressive periosteal reaction. Intense radionuclide uptake of the proximal humerus is noted on a bone scan. The tumor cells vary in size and shape and frequently have large hyperchromatic nuclei. Bizarre tumor giant cells are common, as are mitoses, some of them abnormal (e.g. tripolar). Vascular invasion is usually conspicuous, and some tumors also exhibit extensive necrosis. The formation of bone by the tumor cells is diagnostic. X-RAY FEATURES: - Medullary and coical bone destruction Wide zone of transition, permeative or moth-eaten appearance Aggressive periosteal reaction Sunburst type Codman triangle Lamellated (onion skin) reaction: less frequently seen Soft-tissue mass