Immunohistochemical study of neuron specific enolase expression in salivary-gland tumors

The immunoreactivity of monoclonal anti-neuron-specific enolase (MoAb NSE) on 10% formalin-fixed sections of normal human salivary glands and tumors were examined by the avidin-biotin-peroxidase complex (ABC) method. MoAb NSE staining of ductal and acinar cells of the normal salivary glands were, negative, and peripheral nerve fiber in the gland tissue showed strongly positive staining. In salivary gland tumors, pleomorphic adenoma (34 in total 68), myoepithelioma (15 in 35), monomorphic adenoma (7 in 10), adenolymphoma (15 in 23), mucoepidermoid carcinoma (3 in 16), acinic cell carcinoma (1 in 7), adenoid cystic carcinoma (12 in 20) and sialocarcinoma (4 in 15), stained focally for MoAb NSE staining. Frequency of occurrence for positive NSE activity varies among benign and malignant salivary gland tumors. In addition to MoAb NSE, S-100 protein and GFAP also demonstrated positive reactions in pleomorphic adenoma (Simpson et al Cancer 54: 1364-1369, 1984). The outer layer cells and/or peripheral cells of tubulo-ductal structure as well as modified myoepithelial cells and the cells of solid structure coexpressed with NSE, S-100 protein and GFAP. It is postulated that the salivary gland tumors particularly pleomorphic adenoma may be neuroectodermal in origin, arising from stem cells in intercalated duct segments.