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: Pediatrics
[{'content': 'Which of the following malignancy is classified by Chang staging system? \nSelect and explain. \nA. Retinoblastoma, B. Rhabdomyosarcoma, C. Ewings sarcoma, D. Medulloblastoma', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Medulloblastoma is the most common malignant pediatric brain tumor. They are usually midline. Most occur in the cerebellum and present with symptoms of increased ICP. Histologic characteristics include densely packed small round cells with large nuclei and scant cytoplasm. The Chang staging system is currently used to stage medulloblastomas; it categorizes the tumor by size and metastatic spread. They should undergo surgical resection followed by radiation therapy and chemotherapy. Ref: Principles and Practice of Pediatric Neurosurgery edited by A. Leland Albright, P. David Adelson, Ian F. Pollack, 2008, Page 607.', 'role': 'assistant'}]