Diagnostic Utility of Epithelial Membrane Antigen in Distinguishing Between Reactive Mesothelial and Metastatic Adenocarcinoma Cells in Serous Cavity Fluid



Moghaddam NA¹ ; Mahzouni P¹ ; Rahmani A² ; Khaledi A³ Show Affiliations
Source: Journal of Isfahan Medical School Published:2012

Abstract

Background: The cytological diagnoses of serous effusions are usually made by routine cytomorphology with certainty. However, overlapping cases sometimes exist between reactive mesothelial and adenocarcinoma cells. We tried to evaluate the diagnostic utility of epithelial membrane antigen (EMA) monoclonal antibody in distinguishing between reactive mesothelial cells and adenocarcinoma in serous effusions. Methods: Paraffin blocks and hematoxylin and eosin stained slides of peritoneal and pleural fluid cell blocks were retrieved from cytology archive of Alzahra Hospital, Isfahan University of Medical Sciences, Isfahan, Iran, during 2006-2010. From among 1025 slides which were screened to ascertain their appropriate diagnoses, 90 paraffin embedded cell blocks, 30 cases for adenocarcinoma and 60 cases for reactive mesothelial groups were selected for immunocytochemistry staining. Cellular reactivity, intensity, and pattern of staining for EMA were evaluated by anti-human EMA “clone E29”. Statistical analyses and tests of significance were performed using SPSS. Findings: Mean age of the patients in the reactive mesothelial and adenocarcinoma groups were 50.28 and 55.16 years, respectively. The malignant group included 22 (73.33%) female and 8 (26.66%) male cases. In the reactive group however, 16 (26.66%) females and 44 (73.33%) males were studied. The mean numbers of immunoreactive cells for EMA in adenocarcinomatous and reactive mesothelial cells were 97.5 ± 7.62 and 21.6 ± 30.43, respectively (P = 0.001). In addition, 30 (100%) and 8 (13.33%) severe immunoreactive cases were observed in the metastatic adenocarcinoma and reactive mesothelial groups, respectively (P = 0.001). Conclusion: Immunocytochemical staining for EMA is a useful diagnostic tool for distinguishing effusions containing malignant cells from those with benign cells. We particularly suggest the precise evaluation of pattern and intensity of immunoreactive cells for EMA. © 2012, Isfahan University of Medical Sciences(IUMS). All rights reserved.