<prompt> Periodic Acid Schiff PAS stain positive intra-alveolar material is seen in?Alpha 1 antitrypsin deficiencyPulmonary Alveolar ProteinosisAbetalipoproteinemiaLipoid pneumonia  <response>: 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. 