Does pleural fluid cell block is an alternative to Thoracoscopy guided diagnostic techniques in malignant pleural effusion? Study of 500 cases in tertiary care setting in India

Abstract

Background: Malignant pleural effusion missed routinely because of less diagnostic yield of conventional fluid cytology like fluid cytology. Fluid cell block is underutilsed techniques routinely and less utilized in diagnostic panel due to lack of expertise in filed of cytopathology. Materials and methods: Prospective multicentric study conducted during Jan 2014 to June 2020 in Venkatesh chest hospital, and Pulmonary Medicine, MIMSR medical college Latur, to find out diagnostic yield of conventional pleural fluid cytology& pleural fluid ‘cell block’ in malignant pleural effusion and compare yield of pleural fluid cell block with conventional cytology technique. The study included 500 cases of unexplained, exudative pleural effusion with ADA<30/IU/liter 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 500 cases, mean age of group was 68±9.5 years and adenocarcinoma were predominant malignancy in 79% cases, mesothelioma in 6% cases, squamous cell carcinoma in 7% cases & 8% cases were having primary tumor outside the thoracic cavity. In study cases pleural fluid cytology was positive in 42% cases (210/500), and pleural fluid cell block was positive in 96% cases (480/200) 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. IHC was done in all pleural fluid cell block preparation for calretinin, cytokeratin and EGFR. 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 need for more invasive and costlier diagnostic methods like thoracoscopy and image guided pleural biopsies. We recommend cell block for every exudative pleural fluid sample with ADA<30 IU/liter.