PAS positive

Alveolar proteinosis (PAP), also known as Rosen-Castle-man-Liebow syndrome. It is characterized by PAS staining in the alveolar and bronchiolar lumen, and phospholipid-rich protein material from the lungs. Occurs in young and middle-aged men, about three times as often as men. The etiology is unknown and may be related to immune dysfunction (such as thymic atrophy, immune deficiency, lymphopenia, etc.). Dust, especially animals exposed to silica dust, can cause PAP, so it is thought that it may be a non-specific response to certain irritants, causing alveolar macrophages to break down and produce PAS positive proteins.