This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': "Which of the following is a 'Pulsating tumor' of the bone? \nSelect and explain. \nA. Osteosarcoma, B. Chondrosarcoma, C. Ewing's sarcoma, D. Eosinophilic Granuloma", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Telengiectatic osteosarcoma may present as a pulsatile tumor of bone. Telengiectatic osteosarcoma is an aggressive lytic form of osteosarcoma that occurs as a soft cystic tumor containing aneurysmalty dilated blood filled spaces. Ref: Paediatric and adolescent osteosarcoma by Norman Jaffe, Page 105; Annals of Surgery : Pulsating Tumors Of Bone; Pulsating, Benign Giant Cell Tumors Of Bone; Pulsating Tumors Of The Sternum; Other references.', 'role': 'assistant'}]