Immunohistochemical expression of monoclonal antibody against epithelial membrane antigen in salivary gland tumors.

Abstract

A total of 154 cases of salivary gland tumors were studied by an indirect method with the use of monoclonal antibody to epithelial membrane antigen (EMA) from human milk fat globule membrane. Normal salivary glands displayed positive reaction of EMA staining in the luminal and lateral borders of serous acinar cells, and in the luminal border of ducts. Immunohistochemical expression of EMA in salivary gland tumors was chiefly classified into two types: one is the luminal surface-positive type and the other is the whole cellpositive type. Pleomorphic adenoma was usually positive for EMA staining in luminal borders of tubular, duct-like and cystic structures, and occasionally positive in the cytoplasm of the cells comprising these structures. Warthin's tumor was positive for EMA staining on the luminal surface of eosinophilic tumor epithelial cells, or EMA-positive reaction was evident in various areas scattered throughout the epithelial structures. Acinic cell tumor, carcinoma in pleomorphic adenoma (carcinoma cell), and mucoepidermoid tumor showed positive reaction of EMA staining throughout their cytoplasm depending on histological malignancy. No positive reaction to EMA staining was given by either normal myoepithelial cells, and transformed or neoplastic myoepithelial cells.