9-23: Pulmonary Alveolar Proteinosis

Pulmonary alveolar proteinosis is a rare disease in which periodic acid-Schiff (PAS)-positive phospholipids accumulate 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, and chest radiograph shows bilateral alveolar infiltrates suggestive of pulmonary edema (eFigure 9–16). The diagnosis is based on demonstration of characteristic findings on BAL (milky appearance and PAS-positive lipoproteinaceous material) in association with typical 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. In some cases, transbronchial or surgical lung biopsy (revealing amorphous intra-alveolar phospholipid) is necessary.

The course of the disease varies. Some patients experience spontaneous remission; others develop progressive respiratory insufficiency. Pulmonary infection with Nocardia (eFigure 9–17) or fungi may occur. 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.