Pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis
Other names	alveolar proteinosis
Micrograph of pulmonary alveolar proteinosis, showing the characteristic airspace filling with focally dense globs referred to as chatter or dense bodies. H&E stain.
Specialty	Pulmonology

Pulmonary alveolar proteinosis (PAP) is a rare lung disorder characterized by an abnormal accumulation of surfactant-derived lipoprotein compounds within the alveoli of the lung. The accumulated substances interfere with the normal gas exchange and expansion of the lungs, ultimately leading to difficulty breathing and a predisposition to developing lung infections. The causes of PAP may be grouped into primary (autoimmune PAP, hereditary PAP), secondary (multiple diseases), and congenital (multiple diseases, usually genetic) causes, although the most common cause is a primary autoimmune condition in an individual.