Diagnostic Utility of Epithelial Membrane Antigen (EMA) and Calretinin (CAL) in Effusion Cytology

Introduction: Fluid cytology and subsequent utilization of immunocytology on cell block is being used commonly for increasing the diagnostic accuracy in effusion cytology. Aim: To do cytological analysis of fluids and evaluate the role of Epithelial Membrane Antigen (EMA) and Calretinin (CAL) to differentiate between reactive and malignant cell in pleural and peritoneal fluids. Materials and Methods: This was a prospective study carried out in Department of Pathology, Shri Guru Ram Rai Institue of Medical and Health Science, for a period of 18 months from January 2014 to June 2015. A total of 253 samples of pleural and peritoneal fluid were studied by May-Gruenwald-Giemsa (MGG) stain and Papanicolaou (Pap) staining. In 73 cases which were suspicious for malignancy, cell blocks were prepared and IHC was done using two immunomarkers- EMA and CAL. Results: A total of 253 cases of effusion cytology were studied out of which 73 were found positive for malignant cells. Maximum cases of malignant cells or atypical cells were seen in peritoneal fluid. A total of 34 cases were histologically positive for malignancy. All these cases showed strong membranous and cytoplasmic positivity for EMA. Most of cases also showed 2%-5% positivity for CAL. There were 38 cases categorized as atypical or reactive mesothelial cell hyperplasia. These cases showed nuclear and cytoplasmic staining for calretinin and none of these were positive for EMA, although 5 cases showed score 2-3, which was considered as negative. Conclusion: The distinction between reactive and malignant mesothelial cells in cytological specimens can be problematic. A combination of CAL and EMA may help in accurate diagnosis.