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': 'In a young boy, x-ray of the upper end of the tibia shows a lytic lesion. The least likely diagnosis is- \nSelect and explain. \nA. Giant cell tumor, B. Osteosarcoma, C. Solitary bone cyst, D. Tuberculosis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Giant cell tumour occurs between 20-40 years (not in a young child)\nTelangiectatic type of osteosarcoma, solitary bone cyst and tuberculosis can cause an osteolytic lesion in a child.', 'role': 'assistant'}]