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': 'A 4 years child presents with a history of chronic left lower lobe pneumonitis. On contrast bronchography, the area involved with the pneumonitis does not fill whereas the area around it does fill. The most likely diagnosis – \nSelect and explain. \nA. Asthma, B. Pulmonary sequestration, C. Cystic fibrosis, D. Bronchopulmonary dysplasia', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Sequestrated lung has no connection to airway, so this part does not fill on bronchography. Pulmonary sequestration \nIn this congenital anomaly, there is a discrete mass of lung tissue without any normal connection to the airway system.\nIt may be\n\n\nIntrapulmonary (intralobar) —> More common\nExtrapulmonary (extralobar)\n\n\nSequestrated tissue receives its arterial supply from the systemic arteries (most commonly aorta).\nIt returns blood to the right side of heart through IVC (extrapulmonary sequestration) or pulmonary veins (intrapuhnonary sequestration).\nThe sequestration functions as a space-occupying lesion within chest, it does not function in gas exchange, and does not contribute to a left to right shunt or dead space.\nGastric or pancreatic tissue may also be found in sequestrated segment.\nAssociated anomalies —> cystic adenomatoid malformation, congenital diaphragmatic hernia, esophageal cysts.', 'role': 'assistant'}]