College of Medicine, University of Basrah discussed Board's research on the role of cell mass in immunohistochemistry of epithelial membrane antigen staining and Carleton in the diagnosis of pleural and peritoneal effusion by the postgraduate student, Mrs. Sora Tariq Abd Al-Saied. The research aimed at comparing the shape and diagnostic cuff of the cellular block technique with traditional cytological smears and using of immunohistochemistry to distinguish between reactive epithelial cells and malignant epithelial cells. The research concluded that the importance of cytological examination of serous effusion is well known, the primary role of cytology is to detect malignant tumors and its primary role in the case of malignant metastatic deposition and cytological diagnosis of traditional cytological smears has some defects due to overcrowd and loss of cells, which leads to less cellularity to overcome these defects.