Pulmonary alveolar proteinosis (PAP) is a rare but potentially treatable disease, characterized by impaired surfactant metabolism that leads to accumulation in the alveoli of proteinaceous material rich in surfactant protein and its component. PAP is classified into 2 main types, congenital and acquired. The acquired form is subdivided into the autoimmune form and the secondary form. The vast majority of PAP occurs as an autoimmune PAP. In autoimmune PAP, patients generate antibodies against the granulocyte macrophage colony stimulating factor (GM-CSF) protein. Whole-lung lavage is the most widely accepted therapy for symptomatic PAP. Recent data suggest that exogenous GM-CSF therapy has potential in the treatment of autoimmune PAP. Congenital PAP is also known as pulmonary surfactant metabolism dysfunction (SMDP).
