Immunohistochemical evaluation of superficial and invasive front of oral squamous cell carcinoma using epithelial membrane antigen as a marker

Background: Epithelial membrane antigen (EMA) has been used as a marker for the expression of tumour margins in various glandular neoplastic lesions. Histopathologically, oral squamous cell carcinoma (OSCC) may exhibit several features within the same tumour cells, portraying that these cells at the invasive margins commonly display certain features that differ from those of the superficial part of the tumour. Aim: To identify and study the invasive tumour front and also to recognise any micrometastases in an OSCC lesion. Materials and Method: A retrospective study of 30 OSCC cases with superficial and most invasive parts were sectioned at 4 μm. Routine H&E staining and immunohistochemical staining with mouse antihuman EMA were done. The OSCC cases were graded into well differentiated squamous cell carcinoma (WDSCC), moderately differentiated squamous cell carcinoma (MDSCC) and poorly differentiated squamous cell carcinoma (PDSCC). The EMA-stained slides were observed and analysed under higher magnification to identify the individual EMA-stained cells. Results: Analysis of Variance (ANOVA) analysis revealed that when comparing the superficial and invasive fronts of OSCC, it was evident that the P values were significant across the groups. In WDSCC, positive predictive value was 70.6% and sensitivity was 100% when the same slide was analysed for large and small islands to individual cells in an EMA-stained section, while MDSCC and PDSCC showed both sensitivity and positive predictive value to be 100%. Conclusion: EMA could be considered a useful prognostic marker for describing the nature of the neoplastic epithelium as well as recognising the typical anaplastic cells in cases of OSCC.