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: Orthopaedics
[{'content': "Which of the following is a pulsatile tumour? \nSelect and explain. \nA. Osteosarcoma, B. Chondrosarcoma, C. Ewing's sarcoma, D. Osteoclastoma", 'role': 'user'}, {'content': 'Answer: D \nExplanation: Both osteoclastoma and telangiectatic osteosarcoma can present as pulsatile tumours. However, the best answer here is osteoclastoma, because, telangiectatic osteosarcoma is a less common variant of osteogenic sarcoma. Further, telangiectatic osteosarcoma can be pulsatile in very rare cases. So, the overall frequency is very less.\n\nPulsatile bone tumors\n\nGiant cell tumor (osteoclastoma)\nTelengiectatic osteosarcoma\nAngiosarcoma/angioendothelioma of bone\nAneurysmal bone cyst\nSecondaries from thyroid carcinoma and hypernephroma (renal cell carcinoma).', 'role': 'assistant'}]