May 1st 2007abstract: Pulmonary alveolar proteinosis (PAP) is characterized by the accumulation of lipoproteinaceous material in the alveoli. The most common symptoms are dyspnea on exertion and nonproductive cough. Weight loss, fatigue, chest pain, and hemoptysis have also been reported. Chest radiographs typically show bilateral, symmetrical airspace disease with an ill-defined nodular or confluent pattern, which gives a "bat wing" appearance, as is seen in heart failure. Pulmonary function tests usually demonstrate mild restrictive disease. Findings on examination of sputum specimens or bronchoalveolar lavage fluid can suggest the diagnosis; however, open lung biopsy is the diagnostic gold standard. Whole lung lavage remains the standard of care for PAP and is warranted in patients with severe dyspnea and hypoxemia. Subcutaneous human recombinant granulocyte-macrophage colony-stimulating factor appears to be a promising alternative to whole lung lavage for symptomatic patients. (J Respir Dis. 2007;28(5):177-184)