Immunohistochemical Expression of Sialyl Lewisa in Salivary Gland Tumors

Abstract

Sialyl Lewisa (CA19-9 antigen), a high molecular weight glycoprotein, was originally described as a gastrointestinal tract- and pancreas-specific tumor marker. However, the diagnostic usefulness of sialyl Lewisa expression in salivary gland tumors is not well established. Therefore, we examined the diagnostic significance of sialyl Lewisa (CA19-9 antigen) expression in salivary gland tumors. Surgical materials, consisting of 30 benign (20 pleomorphic adenomas, 5 basal cell adenomas, 5 myoepitheliomas) and 30 malignant (13 mucoepidermoid carcinomas, 13 adenoid cystic carcinomas, 4 salivary duct carcinomas) salivary gland tumors, were subjected to examination in this study. To measure expression of sialyl Lewisa in these tumors, a streptavidin-biotinyl immunoperoxidase method was performed using anti-human CA19-9 antibody. There was a tendency for malignant salivary gland tumors, to express sialyl Lewisa more intensely than benign tumor (P<0.05). As the expression pattern is generally characterized by localization in relatively highly differentiated malignant cells such as mucous-producing cells and atypical luminal duct cells, poorly differentiated tumors such as adenoid cystic carcinoma solid type and salivary duct carcinoma are consistently shown to express sialyl Lewisa less frequently. Five (tubular type 2 and cribriform type 3) of 13 (38.5%) cases were stroma positive for sialyl Lewisa in the adenoid cystic carcinoma. Sialyl Lewisa expression appears to be increased by the malignant transformation of salivary gland tumors. The clinical applications of sialyl Lewisa in patients with salivary gland tumors may be worth examining more closely in the future.