Immunocytochemical panel for distinguishing carcinoma cells from reactive mesothelial cells in pleural effusions

Objective:  The aim of this study was to evaluate the individual and combined diagnostic utility of carcinoembryonic antigen (CEA), cytokeratin 19 fragments (CK19) and HBME-1 in pleural effusions of patients with lung cancer.
Study design:  CEA, CK19 and HBME-1 were detected by immunocytochemistry in pleural effusions from patients with lung cancer (86 cases) and without lung cancer (40 cases).
Results:  CEA and CK19 expression were significantly higher in the carcinoma cell group and in three subgrouped as adenocarcinoma (AC), squamous cell carcinoma (SCC) and small cell lung cancer than in the mesothelial cell group, whereas HBME-1 expression was lower in the former group ( P <  0.01). In the subgrouped tumours, CEA expression was higher in AC than in SCC ( P <  0.05), whereas HBME-1 expression was higher in SCC than in AC ( P <  0.01). Used alone, CK19 had the highest sensitivity (95.3%) and accuracy (93.7%), whereas CEA had the highest specificity (97.5%). When combinations of antibodies were evaluated together and membrane staining with HBME-1 taken as a negative outcome, CK19 and HBME-1 gave a high diagnostic performance: sensitivity of 100.0% and accuracy of 95.2% respectively.
Conclusion:  A panel of CEA, CK19 and HBME-1 monoclonal antibodies proved to be suitable for distinguishing carcinoma cells from reactive mesothelial cells in pleural effusions.