Evaluation of Effusion Fluid (Pleural and Peritoneal) with Special Reference To Cell Block Preparation and Immunohistochemistry for Differentiating Between Reactive Mesothelial and Malignant Effusion

ABSTRACT

Background: The serous cavities are lined by a single layer offlat mesothelial cells called the serosa. Normally these cavitiesare collapsed and contain only a small amount of fluid, enoughto lubricate the adjacent surfaces. Cytological examination ofserous fluid is of paramount importance. It reveals informationabout inflammatory conditions of serous membrane, infectionby bacteria, fungi, virus and presence of malignant cells.Differentiation of population of reactive mesothelial cells fromthose of malignant cells remains a diagnostic challenge inconventional cytological smear. To overcome this challenge,cell block technique along with immunocytochemistry gives abetter histoarchitectural pattern and support immensely forcategorising the effusion to be reactive or malignant.Aims and Objectives: To evaluate utility of cell blocktechnique in effusion fluid (pleural and peritoneal) using limitedimmunohistochemistry markers for differentiating betweenreactive mesothelial and malignant mesothelial cells.Materials and Methods: The present study was carried out inDepartment of Pathology at M.K.C.G MCH, Berhampur,Odisha over a time period from July 2016- July 2018. A total of90 cases were evaluated. The fluids were stained with routinecytological stains. Cases on evaluation of cytomorphology ifsuspicious for malignancy, cell block was prepared. Cell blockwere stained both for routine hematoxylin and eosin andimmunohistochemistry with EMA (Epithelial marker antigen) forepithelial cells and Calretinin for mesothelial cells.Results: A total of 90 cases were evaluated cytologically. 40cases showed benign features and 24 cases showedmalignant features on cytomorphology alone. 26 cases weresuspicious for malignancy which on cell block preparation andimmunocytochemistry were differentiated as benign (10 cases)or malignant (16 cases). EMA showed 97.5 % sensitivity and98% specificity. Calretinin showed 100 % sensitivity and 97.5%specificity.Conclusion: The use of cytopathology of pleural andperitoneal effusion is helpful for early diagnosis and treatment.The technique is cheap, easy to perform and produces speedydiagnosis. In the identification of malignant cells in effusion andits differentiation from cells showing reactive and degenerativechanges there were diagnostic difficulties in some of the cases.Immunocytochemistry is an important diagnostic tool ineffusion cytology.