Immunohistochemical expression of epithelial cell adhesion molecule (EpCAM) in mucoepidermoid carcinoma compared to normal salivary gland tissues

- EpCAM is an epithelial cell adhesion molecule that is highly expressed on majority of carcinomas and therefore may be of diagnostic and prognostic significance as well as a promising target molecule in immunotherapeutic approaches for a variety of carcinomas.
- EpCAM expression was detected in different grades of MEC, and its overexpression correlated with increasing the histological grade which may be associated with proliferation and progression.
- EpCAM could be of diagnostic value in MEC due to the diffuse expression of HG-MEC in relation to the patchy expression in both IMG-MEC and LG-MEC.

ObjectivesMucoepidermoid carcinoma (MEC) is the most common malignant salivary gland tumor which displays biological, histological and clinical diversity thus representing a challenge for its diagnosis and management. Epithelial cell adhesion molecule (EpCAM) is a transmembrane glycoprotein identified as a tumor specific antigen due to its frequent overexpression in the majority of epithelial carcinomas and its correlation with prognosis. It is considered to be a promising biomarker used as a therapeutic target already in ongoing clinical trials. The purpose of this study was to investigate the pattern, cellular characterization and level of EpCAM expression in MEC and demonstrate its correlation with histologic grading which may benefit future clinical trials using EpCAM targeted therapy.Materials and methods48 specimens (12 normal salivary gland tissue and 36 MEC) were collected and EpCAM membranous expression was evaluated by immunohistochemistry. Total immunoscore (TIS) was evaluated, the term 'EpCAM overexpression' was given for tissues showing a total immunoscore >4.ResultsA highly significant difference was observed between TIS percent values in control and different grades of MEC (p < 0.001). High grade MEC (HG-MEC) was the highest EpCAM expressor. In addition, EpCAM expression pattern differed among the different grades.ConclusionEpCAM expression was detected in MEC, and its overexpression correlated with increasing the histological grade. The diffuse membranous expression in HG-MEC could be of diagnostic value in relation to the patchy expression observed in both low grade and intermediate grade MEC.