Pulmonary alveolar proteinosis in children.

Pulmonary alveolar proteinosis (PAP) is a rare cause of chronic interstitial lung disease in children characterised by accumulation of a lipoproteinaceous material in the alveoli. Bronchoalveolar lavage is the key diagnostic tool, revealing a milky appearance of the return fluid and a periodic acid-Schiff staining material in the alveolar macrophages. PAP is a heterogeneous disease. Immediate-onset forms leading to early and fatal respiratory failure may be related to SP-B deficiency. Postnatal-onset PAP may be associated with various diseases or may be primary. The latter has a polymorphic progression from asymptomatic to uncontrollable respiratory failure. Recent studies have implicated GM-CSF and/or its receptor but the exact underlying mechanisms are still unknown. Therapeutic lung lavages are the only effective treatment for severe cases.