pulmonary disorders
Pulmonary Alveolar Proteinosis
Diagnosis of Pulmonary Alveolar Proteinosis
Bronchoalveolar lavage Sometimes biopsy Pulmonary alveolar proteinosis is usually first suspected when a chest x-ray is taken for nonspecific respiratory symptoms. The x-ray shows bilateral mid- and lower-lung field opacities in a butterfly distribution with normal hila. Bronchoalveolar lavage is done. Lavage fluid is milky or opaque and stains positive with periodic acid–Schiff (PAS) staining. Lavage fluid is characterized by scattered surfactant-engorged macrophages, an increase in T cells, and high levels of surfactant apoprotein-A. Thoracoscopic or open lung biopsy is done when bronchoscopy is contraindicated or when specimens from lavage fluid are nondiagnostic. Tests typically done before treatment begins include Arterial blood gas measurements (ABGs) High-resolution CT (HRCT) Laboratory tests Pulmonary function tests ABGs may show hypoxemia with mild to moderate exercise or at rest if disease is more severe. HRCT shows ground-glass opacification, thickened intralobular structures, and interlobular septa in typical polygonal shapes (crazy-paving). This finding is not specific, however, as it may also occur in patients with acute respiratory distress syndrome (ARDS), viral pneumonia, lipoid pneumonia, bronchoalveolar cell carcinoma, andPneumocystis jiroveciipneumonia. Overview of Tests of Pulmonary Function show reduction in diffusing capacity for carbon monoxide (DLCO) that is disproportionate to the decreases in vital capacity, residual volume, functional residual capacity, and total lung capacity. Laboratory test abnormalities include polycythemia, hypergammaglobulinemia, increased serum lactate dehydrogenase levels, and increased serum surfactant proteins A and D. Abnormalities are suggestive but nondiagnostic. Laboratory tests for antibodies to granulocyte-macrophage colony-stimulating factor (GM-CSF) and GM-CSF serum levels can help support a diagnosis of pulmonary alveolar proteinosis. 