Expression of MUC1, MUC2 and MUC5AC in salivary gland mucoepidermoid carcinoma: A case series with diagnostic implications

CONTEXT: Mucoepidermoid Carcinoma (MEC) accounts for 10–15% of all salivary gland neoplasms and its management is related to tumour grading. The expression of mucin in the tumour cells presumably affects and predicts tumour behaviour. AIMS: To analyse the expression of MUC1 (membrane bound mucin), MUC2 and MUC5AC (secreted mucins) in mucoepidermoid carcinoma and correlate with tumour grade and patient outcome. SETTINGS AND DESIGN: In this retrospective correlation study the expression of MUC1, MUC2 and MUC5AC were investigated using immunohistochemistry in confirmed cases of MEC. METHODS AND MATERIAL: The staining patterns of MUC1, MUC2 and MUC5AC were analysed in 10 confirmed cases from the year 2013 to 2020. STATISTICAL ANALYSIS USED: SPSS 23 was used for bivariate correlations. RESULTS: All of the tumours expressed MUC1, showing strong membranous to focal cytoplasmic localization in all cells. The goblet cell component expressed a strong apical membranous pattern. MUC2 expression was moderate, showed cytoplasmic localisation in 40% of mucinous cells and was minimal in intermediate cells and epidermoid cells. MUC 5AC expression was strong apical membranous in goblet cells and mainly negative in intermediate cells and epidermoid cells. CONCLUSIONS: Although MUC1 is a reliable marker for all cell types of MEC but has no significant correlation with the tumour grade. MUC 2 has not been found to be a reliable diagnostic marker and has no significant correlation with the tumour grade. MUC 5AC has been found to have a significant expression in tumours with lymphoid infiltrate. There was no statistically significant correlation of MUC expression with the site, tumour grade and patient outcome.