This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bone Tumour, Subject name: Orthopaedics
[{'content': 'Simple bone cyst is most commonly seen in - \nSelect and explain. \nA. Proximal humerus, B. Proximal tibia, C. Distal tibia, D. Distal humerus', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Proximal humerus Simple Bone Cyst* This lesion is also known as a solitary cyst or unicameral bone cyst.* It appears during childhood, typically in the metaphysis of one of the long bones and most commonly in the proximal humerus or femur.* It is not a tumor, it tends to heal spontaneously and it is seldom seen in adults. The condition is usually discovered after a pathological fracture or as an incidental finding on x-ray.* X-rays show a well-demarcated radiolucent area in the metaphysis, often extending up to the physeal plate; the cortex may be thinned and the bone expanded. Fallen fragment sign is seen if pathological fracture develops. After pathological fracture a cortical fragment is seen in the most dependent portion of cyst, like a fallen fragment.", 'role': 'assistant'}]