Presenting shortly after birth (congenital PAP) u Gradually progressive form -->           Presenting in older infants and children Pathology Although the mechanisms that lead to alveolar proteinosis are undefined, histological findings suggests that they result in a disruption of pulmonary surfactant metabolism. The main surface tension lowering agent in surfactant is phospholipids le. primary dipalmitol phosphatidyl choline. However DPCC needs surfactant protein (in endogenous and natural surfactants) for efficient dispersion which enables the formation of a phospholipid monolayer on the alveolar surface. There are two surfactant proteins present in the body i.e., protein A and protein B. In pulmonary alveolar proteinosis, there is absence of protein B. In the absence of protein B, the rapid spread and absorption of the phospholipid (DPCC) does not take place so they cannot form a phospholipid monolayer on the alveolar surface. This in turn leads to failure of expansion of alveoli leading to poor cardiorespiratory adaptation at birth. Clinical manifestation - This disorder is immediately apparent in the newborn period and rapidly leads to respiratory failure. Congenital pulmonary alveolar proteinosis is clinically and radiographically indistinguishable from more common disorders of the newborn that lead to respiratory failure including pneumonia, generalized bacterial infection, respiratory distress syndrome and total anomalous pulmonary venous return with obstruction. Diagnosis Histopathological examination of lung biopsy specimen is the gold standard for diagnosis. On histopathological examination distal air spaces are filled with a granular, eosinophillic material that stains positively with periodic - acid schiff reagent and is diastase resistant. Treatment Untreated, alveolar proteinosis in newborns is rapidly fatal and no successful medical therapy has been developed. Repeated bronchoalveolar lavage is a temporizing measure. Lung transplantation is the only therapeutic option but its use is limited by concerns about disease recurrence.">