Immunohistochemical detection of E-cadherin in certain types of salivary gland tumours

Abstract

To investigate the topography of E-cadherin and its possible correlation with the histological phenotype of salivary gland tumours. Archival formalin-fixed, paraffin-embedded sections of 54 benign and 56 malignant tumours and 24 samples of normal and inflamed salivary gland tissue were studied immunohistochemically using an Envision/horseraddish peroxidase (HRP) technique. In normal and inflamed salivary gland samples, E-cadherin was expressed at the membrane of acinar, myoepithelial and ductal cells located at cell-cell contact points. Reduction and/or absence of E-cadherin was only observed in pleomorphic adenoma at the peripheral cells of the duct-like or island structures, or in the cells exhibiting plasmacytoid or stromal differentiation. Neoplastic epithelium in Warthin's tumours and in myoepithelial and oncocytic adenomas was strongly positive. Furthermore, a weak to moderate loss of expression which was related to tissue tumour subtype was seen in malignant tumours such as: adenoid cystic carcinomas; polymorphous low-grade adenocarcinomas; acinic cell carcinomas; and mucoepidermoid low-grade, epithelial-myoepithelial, lymphoepithelial and squamous low-grade carcinomas. Moderate to extreme loss or alternative cytoplasmic non-functional expression were observed in cases of salivary ductal carcinoma, carcinosarcoma, myoepithelial carcinoma, oncocytic adenocarcinoma, unspecified adenocarcinoma and squamous high-grade carcinomas. This study suggests a direct association of E-cadherin expression with neoplastic histologic phenotype, which is lost in the more undifferentiated and invasive epithelial salivary gland tumours.