Spearman's correlation coefficients obtained for the correlations between adenosine deaminase and cytokeratin 19 fragments in pleural fluids were significantly positive for adenocarcinomas and significantly negative for a heterogeneous group of other diseases, including Dressler syndrome, melanocarcinoma, chylothorax, and leukemia, as shown in Table 3. This evidence concerns the gene KRT19 and leukemia.