Introduction: Effusion of serous cavities is commonly encountered in clinical practice. If we know the primary site, it is possible to avoid the unnecessary exploratory surgery. Diagnostic paracentesis should be a part of the routine evaluation of the patient with effusion. In many cases, a definitive diagnosis cannot be reached based on morphology alone; thus, the diagnostic yield and its accuracy in effusion cytology can be enhanced though the utilization of ancillary techniques. Many previous studies have shown the role of immunocytochemical (ICC) in diagnosis in malignant cells. Material and Method: 55 cases of serous effusions were included in this study. Routine examination of specimen was done after proper patient identifications. For Immunocytochemistry Polymeric technique was performed on cell smear preparation, prepared earlier. Results: in the present study cytological evaluation along with immunocytochemical analysis of 55 cases, presenting with serous effusion was done. The patients were of the age range from 19 to 77 years. We studied 55 effusion fluids in which 23 (41.81%) effusions were found to be of inflammatory etiology because of predominance of inflammatory cells and reactive mesothelial cells in them, followed by 21 (38.18%) fluids showing malignant metastatic deposits. All prepared smears were then subjected for immunocytochemical staining utilizing antibody for CEA, and cytokeratin. Positive immunostaining for CEA was obtained in 11 out of 21 cytological malignant effusions. All the epithelial origin tumors including squamous cell carcinoma and mesothelioma are positive for cytokeratin. Adenocarcinoma are negative for cytokeratin Unequivocal cytoplasmic staining observed in >20–30% tumor cells was considered positive. Positive immunostaining for cytokeratin was obtained in three cases out of 21 cytologically malignant effusions. Cytokeratin was consistently absent in all the cytologically benign effusions. Discussion: ICC is an established important adjunct diagnostic tool for differentiate among various tumors. This study was designed to study the immunocytochemical reactivity patterns of various antibodies with cells of malignant and benign effusions and to evaluate their potential role in routine diagnostic cytology. Conclusions: CEA was found to be 64.28% sensitive in cytologically positive cases of adenocarcinoma similarly Cytokeratin has 75% sensitivity as a tumor marker in cytologically positive cases of squamous cell carcinoma.

Keywords: Immunocytochemistry; Effusion; CEA; Cytokeratin; Malignancy; Adenocarcinoma; Squamous cell carcinoma.