Fractional analysis of the 120-ml bronchoalveolar lavage. Determination of the best specimen for diagnosis of sarcoidosis

Abstract

Study design: Bronchoalveolar lavage with seven 20-ml aliquots was performed on 9 patients with sarcoidosis and 11 patients with idiopathic pulmonary fibrosis (IPF). The returns from the first 20-ml aliquot (volume 1), the next 100 ml of bronchoalveolar lavage fluid (volume 2), and the last 20 ml of lavage fluid (volume 3) were analyzed separately for cell content and differential cell counts. The cell content was calculated four different ways, including absolute number of cells per milliliter of return and as a differential cell count using three different denominators. The denominators used were (1) neutrophils, lymphocytes, eosinophils, macrophages, and epithelial cells; (2) neutrophils, lymphocytes, eosinophils, and macrophages; and (3) neutrophils, lymphocytes and eosinophils. The data were analyzed to see what volume and arithmetic expression of cell content provided the best means of distinguishing sarcoidosis from IPF.

Results: The results confirmed a proximal distribution of the first 20-ml aliquot with more bronchial epithelial cells and neutrophils than volumes 2 and 3. There were more macrophages and lymphocytes in volumes 2 and 3 than in volume 1. Volumes 2 and 3 had similar cell content. Sequential fractional analysis showed that the cells in volume 2 and 3 more clearly distinguished sarcoidosis from IPF than the cell content of volume 1.

Conclusion: The presence of lymphocytes, and especially a predominance of lymphocytes with the relative absence of neutrophils, correlated best with sarcoidosis. The percentages of differential cell counts proved superior to both the absolute number of neutrophils and of lymphocytes per milliliter of return in distinguishing sarcoidosis from IPF. A percentage differential cell count with a denominator of neutrophils+lymphocytes+eosinophils provided the best means of distinguishing between sarcoidosis and IPF.