A 3.5 kg male infant born at term after an uncomplicated pregnancy and delivery develops respiratory distress sholy after bih and requires mechanical ventilation. The chest radiograph reveals a normal cardiothymic silhouette but a diffuse ground glass appearance to the lung fields. Surfactant replacement fails to improve gas exchange. Over the first week life, the hypoxemia worsens. Results of routing culture and echocardiographic findings are negative. A term female sibling died at 1 month of age with respiratory distress. Which of the following is the most likely diagnosis?

Ans: A. Neonatal pulmonary alveolar proteinosis(Ref. Nelson 20/e p852, 2119)Suggestive of neonatal pulmonary alveolar proteinosis.Pulmonary alveolar proteinosis:Disorder characterized by intra-alveolar accumulation of pulmonary surfactant.Two clinically distinct forms of pulmonary alveolar proteinosis are seen:Fatal form: Presenting sholy after bih (congenital PAP)Gradually progressive form: Presenting in older infants & children.Clinical manifestation:Immediately apparent in the newborn period & rapidly leads to respiratory failure.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.