This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Interstitial Lung Disease, Subject name: Medicine
[{'content': 'Periodic Acid Schiff (PAS) stain positive intra-alveolar material is seen in? \nSelect and explain. \nA. Alpha 1 antitrypsin deficiency, B. Pulmonary Alveolar Proteinosis, C. Abetalipoproteinemia, D. Lipoid pneumonia', 'role': 'user'}, {'content': 'Answer: B \nExplanation: PAS material in alveoli is accumulated surfactant due to decreased turnover in pulmonary alveolar proteinosis. Characterized by dysfunction of alveolar macrophages which results in decreased surfactant clearance The same material may be coughed up by patients and described as chunky gelatinous plugs. Lipoid pneumonia will show fat globules in macrophages.', 'role': 'assistant'}]