This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Childhood tumors, Subject name: Pediatrics
[{'content': 'Young child with mass in posterior cranial fossa showing mural nodule. Diagnosis is \nSelect and explain. \nA. Hemangiocytic pericytoma, B. Astrocytoma (Pilocytic), C. Ependymoma, D. GBM', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Pilocytic astrocytoma is a well defined glial cell tumor,presenting as a large cystic lesion with a brightly enhancing mural nodule.Calcification can be present in around one- fifth of the cases.They typically arise from the midline structures,& around 60% are in cerebellum. Associations: There is a strong association with , there is predominantly a mass effect with signs of raised intracranial pressure, especially when hydrocephalus is present. Bulbar symptoms or cerebellar symptoms may also be present. Reference: GHAI Essential pediatrics, 8th edition', 'role': 'assistant'}]