The cytologic evaluation of lipid-laden alveolar macrophages as an indicator of aspiration pneumonia in young children.

Gastroesophageal reflux with aspiration of feedings in infants and young children may be involved in the development of chronic lung damage. Our laboratory has utilized tracheal aspirates stained with oil red O to identify and quantitate lipid-laden alveolar macrophages as a marker of such aspiration. During the last 10 years, we have evaluated 244 tracheal aspiration smears in children. Although a few patients were up to 3 years old, the vast majority were infants. The cytologist looked for the presence of and the number of oil red O-positive macrophages on tracheal aspirate smears. The specimens were easily assigned grades of absent (grade = 0), low positive (grade 1: 1-25 lipid-laden macrophages), moderate positive (grade 2: 26-50 lipid-laden macrophages), and high positive (grade 3: > 50 lipid-laden macrophages). The grade was then correlated with the positive or negative clinical diagnosis of gastroesophageal reflux with aspiration. We believe the cytologic evaluation and grading of oil red O-stained tracheal aspirates for lipid-laden macrophages is valuable in identifying these patients with gastroesophageal reflux and aspiration.