Objective: This investigation describes the CT features of pulmonary alveolar proteinosis in a large group of patients.
Materials and methods: A retrospective review of 139 chest CT scans (79 thick-section scans and 60 thin-section scans) from 27 patients with pathologically proven pulmonary alveolar proteinosis was performed. Two independent observers assessed the intraslice patterns and zonal distribution of disease on three CT images of each lung. The observers also graded the percentage of ground-glass opacities, air-space opacities, fibrosis, interlobular opacities, intralobular opacities, and emphysema in each slice. CT scans obtained before and after lavage related to 12 whole-lung lavage treatments on nine patients were evaluated.
Results: The dominant intraslice pattern was geographic, but a diffuse pattern was sometimes seen. The most common zonal pattern was uniform; a lower zone predominance was next most frequent. Ground-glass, air-space, and fibrotic opacities had a generally homogeneous craniocaudal distribution, but there was a trend toward more interlobular opacities at the lung bases (p < 0.002). Ground-glass opacities were seen on at least one scan in 100% of the patients. Interlobular opacities (85%), air-space opacities (78%), substantial fibrosis (7%), and intralobular opacities (7%) occurred less frequently. Compared with thick-section images, thin-section images showed more interlobular opacities, but no difference in ground-glass, air-space, or fibrotic disease. The proportion of lung affected by ground-glass and interlobular opacities decreased significantly (p < 0.05) after lavage.
Conclusion: Pulmonary alveolar proteinosis does not present only with alveolar disease. The CT appearance typically combines different types of opacities with a geographic pattern and a uniform zonal distribution with variation over time.