Concordance between conventional cytology and cell block of suspected malignant pleural effusion: A record-based study in a tertiary care center of eastern India

Abstract

Background: Cytological study of pleural fluid helps establishing the underlying cause of pleural effusion. It is considered the most important tool in diagnosing malignancy in effusions. However, accurate identification of cellular morphology can be a problem in conventional cytology. Cell block preparation from pleural effusion aids in this diagnosis due to the preservation of tissue architecture, and multiple sections can be obtained for further studies. Aims and Objectives: The objectives of this study were to compare the diagnostic results of conventional cytology and cell block studies of suspected malignant pleural effusions and find out the diagnostic agreement or concordance between the two methods. Materials and Methods: A record-based study was conducted at the Department of Pathology on conventional cytology and cell block study reports of 150 suspected malignant pleural effusion cases over 35 months. The diagnoses were expressed in five categories – non-diagnostic, negative for malignancy, atypia of undetermined significance, suspicious for malignancy, and malignant. χ2 test was used to identify the percentage of malignancy reported. Agreement of both methods was assessed through Kappa statistics. Results: About 4.67% of cases were reported as malignant by conventional cytology, whereas cell block study diagnosed malignancy in 19.33% of cases. Relative diagnostic agreement between the two methods was 0.73 and concordance by Cohen’s Kappa was 0.34, which signifies fair concordance. Conclusion: Cell block study, though having a fair concordance, is much superior to conventional cytology smears in detecting malignant cells and diagnosing a pleural effusion as malignant.