Intraalveolar phospholipid accumulation Pulmonary alveolar proteinosis Alveolar proteinosis Accumulation of amorphous PAS-positive material in the space between alveolar macrophages, sometimes as condensed form (oval bodies) are typically found in alveolar proteinosis. HP:0006517 HP:0032982 Detection of PAS-positive extracellular material in broncho-alveolar lavage UMLS:C0034050 SNOMEDCT_US:10501004 The periodic acid Schiff (PAS) staining is a staining method that detects polysaccharidese and mucosubstances, for example: glycogen, glyolipids, glyoproteins and mucins. It is one of the commonly used procedures in the histophathology laboratory and is easy to perform. It may help in discriminating different forms of interstitial lung disease (ILD), especially pulmonary alveolar proteinosis (PAP). Abnormal bronchoalveolar lavage fluid morphology