Contribution of Cell Block Obtained by Thoracentesis in the Diagnosis of Malignant Pleural Effusion.

Aim: The aim of this study wass to compare the cytological features of pleural exudative fluids by conventional smear (CS) method and cell block (CB) method and also to assess the utility of the combined approach for cytodiagnosis of these effusions.

Materials And Methods: In all, 113 pleural exudative fluid samples were subjected to evaluation by both CS and CB methods over a period of 2 years. Cellularity, architecture patterns, morphological features, and yield for malignancy were compared, using the two methods. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for diagnosis of malignancy were calculated for both the methods, using histology as a gold standard.

Results: CB method provided higher cellularity, better architectural patterns, and additional yield for malignancy when compared with CS method. For 22 (40%) patients, histologic subtype was determined with CB especially for adenocarcinoma. The sensitivity, specificity, positive, and negative predictive values of cytology and CB were 48%, 100%, 100%, 67.8% and 59.2%, 100%, 100%, 72.8%, respectively.

Conclusion: CB technique definitively increased detection of malignancy in pleural fluid effusion when used as an adjunct to CSs. Also, CB provides material suitable for molecular genetic analysis for targeted therapies especially in the treatment of adenocarcinoma.