Pulmonary alveolar proteinosis is a rare disease characterized by accumulation of lipoproteinaceous material within alveolar spaces. The condition may be primary (idiopathic) or secondary (occurring in immunodeficiency; hematologic malignancies; inhalation of mineral dusts; or following lung infections, including tuberculosis and viral infections). Progressive dyspnea is the usual presenting symptom. Chest radiograph shows bilateral alveolar infiltrates, and chest CT features a characteristic “crazy-paving” that refers to ground-glass opacities with superimposed interlobular and intralobular septal thickening. The diagnosis is based on demonstration of characteristic findings on BAL (milky appearance and periodic acid-Schiff [PAS]-positive lipoproteinaceous material) in association with clinical and radiographic features. In secondary disease, an elevated anti-GM-CSF (anti-granulocyte-macrophage colony-stimulating factor) titer in serum or BAL fluid is highly sensitive and specific.
The course of the disease varies. Some patients experience spontaneous remission; others develop progressive respiratory insufficiency. Therapy for alveolar proteinosis consists of periodic whole-lung lavage. Patients who cannot tolerate whole lung lavage or who fail to respond may benefit from inhalational or subcutaneous GM-CSF. Pulmonary infection with Nocardia or fungi may occur.
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