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BACKGROUND: All malignant tumors may spread throughout the pleural, peritoneal, and pericardial cavities. The presence of tumor cells in serosal fluid is a poor prognostic indicator. It may be difficult to differentiate nuclear atypia of mesothelial cells due to injury of serosal surfaces from mesothelioma or malignant epithelial tumor cells. Epithelial and mesothelial immunohistochemical markers can be used in such conditions. The aim of this study was to evaluate the expression of two immunohistochemical markers (MOC-31 and EZH2) in serosal effusions. METHODS: The study included a total of 142 patients diagnosed with benign or malignant cytology between January 2012 and April 2014. MOC-31 and EZH2 were applied to the cell blocks of 53 patients with benign cytology and 89 patients with malignant cytology determined based on the clinical, radiological data, histopathology diagnosis, and clinical follow-up in the absence of any surgical material of the patient in the hospital archive system. RESULTS: None of the benign cases showed MOC-31 and EZH2 expression, although these markers were positive in 96 and 93% respectively of the malignant cases. CONCLUSION: In conclusion, it could be considered cost-effective to use a double immunohistochemical antibody kit for these two markers, MOC-31 membranous and EZH2 nuclear staining, in the diagnosis of malignant effusions. Diagn. Cytopathol. 2017;45:118-124. © 2016 Wiley Periodicals, Inc.

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OBJECTIVES: To identify useful biomarkers for differentiating between malignant mesothelioma (MM) and reactive mesothelial cells (RMCs). METHODS: Formalin-fixed, paraffin-embedded (FFPE) tissues from 34 MM and 40 RMC samples were analyzed using immunohistochemistry, and the findings were compared. RESULTS: Positive markers for MM included insulin-like growth factor 2 messenger RNA binding protein 3 (IMP3), glucose transporter 1 (GLUT1), epithelial membrane antigen (EMA), and CD146, which showed sensitivities of 94%, 85%, 79%, and 71% and specificities of 78%, 100%, 88%, and 98%, respectively. In sarcomatoid MM, EMA had significantly lower expression than did IMP3, GLUT1, and CD146 (P < .001). The areas under receiver operating characteristic curves were the highest for IMP3 (0.95), followed by GLUT1 (0.93). When the optimal cutoff points for IMP3 (30%) and GLUT1 (10%) were used, the sensitivity of IMP3 and GLUT1 for MM was 100%, and the specificity of both for MM was 95%. CONCLUSIONS: The combination of IMP3 and GLUT1 is most appropriate for distinguishing MM from RMC using FFPE sections.

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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 proliferative index using a Ki-67 monoclonal antibody in distinguishing between reactive mesothelial cells and adenocarcinoma in serous effusions. MATERIALS AND METHODS: Paraffin blocks and H and E stained slides of peritoneal and pleural fluid cell blocks were retrieved from cytology archive of Alzahra Hospital, Medical University of Isfahan, between 2006 and 2010, from among 1025 slides which were screened to ascertain their appropriate diagnoses. Among of these 80 paraffin-embedded cell blocks, 40 cases for each reactive and adenocarcinoma groups were selected. The proliferative index was calculated by using the Ki 67 monoclonal antibody against nuclear proteins. RESULTS: The mean ages of the patients in the reactive mesothelial and adenocarcinoma groups were 60.58 and 58.45 years, respectively. The gender distribution for the malignant group included 23 cases (%57.5) of females and 17 cases (42.5%) of males. This ratio for reactive group included 14 cases (35%) and 26 cases (65%). The mean of Ki-67 index in adenocarcinomatous cells was 17.15 (SD=15.11) and in reactive mesothelial cells was 3.58 (SD= 3.59) (P=0.001). We consider to using the proliferative marker of Ki-67 on benign and malignant lesions revealed 12% as cut off level. The means of Ki-67 index according to serousal spaces were included: Pleura: 10.56 (SD= 13.06) and peritoneum: 10.03 (SD= 12.78), (P=0.9). CONCLUSION: Ki-67 index is useful immunostaining panel for differentiation of mesothelial and adenocarcinoma cells in malignancy like ovarian carcinoma that sometimes mimics mesothelial morphology.

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BACKGROUND: One of the problems in studying serous effusion cytological samples is differentiation of reactive mesothelial cells from metastatic adenocarcinoma cells. MATERIALS AND METHODS: In this study, the immunohistochemical diagnostic value of E-cadherin and fibronectin markers for differentiation of these 2 groups of cells was studied. 50 cell block samples prepared from serous effusions were examined. Based on clinical and histological studies, 25 cases had primary carcinoma, and the other 25 were proved to be benign effusion cases. All the cases were studied for E-cadherin and fibronectin immunostaining using an envision technique. Statistical analyzes were performed employing Chi-square and exact Fisher tests, using SPSS software (version 16). RESULTS: 24 of the 25 benign cases were stained with fibronectin and 2 with E-cadherin, whereas from among the 25 metastatic cases, 2 reacted to fibronectin and 22 to E-cadherin. Considering the staining of the 2 markers under conditions that the cells were stained with fibronectin but not with E-cadherin, positive predictive value (PPV) and negative predictive value (NPV) to identify reactive mesothelial cells were 100% and 92.5% while under conditions that had not been stained with fibronectin but with E-cadherin, PPV and NPV to detect adenocarcinoma cells were 95.2% and 82.1%, respectively. CONCLUSION: Employing this short panel can be helpful for better differentiation of adenocarcinoma and reactive mesothelial cells in serous fluids.