A comparative study of conventional cytology and cell block method in the diagnosis of pleural effusion

Abstract

Introduction: In a patient with pleural effusion, cytological analysis is one of the most useful investigations, especially in suspicion of malignancy. Instead of submission only the cytological analysis, the pleural fluid can be further processed with the cell block technique, which may augment the diagnostic utility. Objective: To compare diagnostic yields of the cytological analysis, the cell block technique and the combination of both, regardless of the etiologies of pleural effusion. Methods: A cross-sectional study was conducted on patients with pleural effusion who underwent thoracocentesis. All samples were submitted for biochemical analysis, cytology, and cell block histology. The results of cytopathological studies were compared to the final diagnoses. Results: Of the total 185 samples, the final diagnoses included 148 (80%) malignancies, 17 (9.2%) infections, 3 (1.6%) specific inflammatory diseases, 11 (5.9%) transudative pleural effusions, and 6 (3.2%) non-diagnoses. The Kappa-statistic showed a substantial agreement between cytology and cell block histology (k=0.75). The cytological study and the cell block technique equally provided a diagnostic yield of 52%, while the combination of both gave a higher yield (58%) than each technique (p=0.002). Among 148 malignant pleural effusions, the diagnostic yields of cytology and cell block histology were 64.2% and 62.8%, respectively. Combined cytology and cell block histology improved a diagnostic yield to 71.4% (p=0.004). Conclusions: The cell block method provides a similar diagnostic performance to the conventional cytological analysis. Submission of both techniques can significantly increase the diagnostic yield.