Diagnostic utility of the cell block method versus the conventional smear study in pleural fluid cytology

The cytological examinations of serous effusions have been well-accepted, and a positive diagnosis is often considered as a definitive diagnosis. It helps in staging, prognosis and management of the patients in malignancies and also gives information about various inflammatory and non-inflammatory lesions. Diagnostic problems arise in everyday practice to differentiate reactive atypical mesothelial cells and malignant cells by the routine conventional smear (CS) method.

To compare the morphological features of the CS method with those of the cell block (CB) method and also to assess the utility and sensitivity of the CB method in the cytodiagnosis of pleural effusions.

The study was conducted in the cytology section of the Department of Pathology. Sixty pleural fluid samples were subjected to diagnostic evaluation for over a period of 20 months. Along with the conventional smears, cell blocks were prepared by using 10% alcohol-formalin as a fixative agent. Statistical analysis with the 'z test' was performed to identify the cellularity, using the CS and CB methods. Mc. Naemer's χ(2)test was used to identify the additional yield for malignancy by the CB method.

Cellularity and additional yield for malignancy was 15% more by the CB method.

The CB method provides high cellularity, better architectural patterns, morphological features and an additional yield of malignant cells, and thereby, increases the sensitivity of the cytodiagnosis when compared with the CS method.