Role of pleural fluid “Cell Block” in malignant pleural effusion: Underutilized, sensitive, and superior over conventional fluid cytology; Does it will decrease need for thoracoscopy guided procedures?

Background: Malignant pleural effusion missed routinely because of less diagnostic yield of conventional fluid cytology. Materials and Methods: Prospective multicentric study conducted during January 2014 to June 2016 in Venkatesh chest hospital, and Pulmonary Medicine, MIMSR medical college Latur, to find diagnostic yield of conventional pleural fluid cytology and pleural fluid “cell block” in malignant pleural effusion and compare yield of pleural fluid cell block with conventional cytology technique. The study included 200 cases of unexplained, exudative pleural effusion with Adenosine deaminase (ADA) ≤30/IU/l and pleural fluid cytology is either positive for malignant cell with or without cell type differentiation, or cytology suspicious for malignant cell. All cases were subjected to cell block preparation. Statistical analysis was done by using Chi-test. Observation and Analysis: In study of 200 cases, mean age of group was 68 ± 9.5 years and adenocarcinoma was predominant malignancy in 72% cases, mesothelioma in 10% cases, squamous cell carcinoma in 7% cases and 9% cases were having primary tumor outside the thoracic cavity. In study cases, pleural fluid cytology was positive in 42% cases (84/200), and pleural fluid cell block was positive in 96% cases (192/200) in detecting malignant pleural effusion (P < 0.0001). Remaining six and two cases were diagnosed by using image-guided and thoracoscopy-guided pleural biopsies, respectively. Immunohistochemistry (IHC) was done in all pleural fluid cell block preparation for calretinin, cytokeratin, and epidermal growth factor receptor. Conclusion: Pleural fluid cell block is sensitive, superior, cost-effective, and specific diagnostic method over conventional pleural fluid cytology. “Cell block” specimens are enough for primary diagnosis and IHC analysis necessary for cell typing. It will decrease the need for more invasive and costlier diagnostic methods like thoracoscopy and image-guided pleural biopsies. We recommend cell block for every exudative pleural fluid samples with ADA <30 IU/l.