Particulate concentrations in pulmonary alveolar proteinosis.

Quantitative birefringent particle counts per 10 high-power fields in lung tissue were correlated with age, sex, and occupational exposure in 37 cases of pulmonary alveolar proteinosis. Counts were significantly higher in pulmonary alveolar proteinosis cases in both regions of alveolar proteinosis (47 +/- 11) and perivascular and peribronchiolar areas (dust retention areas) (275 +/- 65) than in 13 controls (5 +/- 3 and 79 +/- 23, respectively). Of a total of 8619 particles, 4817 were less than 1 micron, and 3771 were 1 to 10 microns in diameter. Fifty-nine percent were round, 19% fibrous, and 22% irregular. When analyzed individually, 20 of 37 cases (78%) had alveolar particle counts significantly higher than controls, and 10 of 26 cases had dust-retention area counts greater than controls (P less than 0.050). Known or possible occupational exposure was ascertained in 13 cases. In the remaining 24 cases insufficient occupational information was available. The mean age of the pulmonary alveolar proteinosis patients was 33 +/- 4 years, and of the controls, 40 +/- 7 years, and there was a male-to-female ratio of approximately 3:1. We propose that many cases of pulmonary alveolar proteinosis will ultimately be shown to be associated with environmental exposures to fine dusts or fumes.