Proliferating patterns of salivary gland adenocarcinomas with the use of PCNA labeling

Cellular proliferation activity in a series of salivary gland malignant tumors was evaluated using the index of proliferation cellular nuclear antigen (PCNA) immunoreactivity. A streptavidin-biotin immunoperoxidase method (ABC) using a monoclonal antibody PC10 demonstrated nuclear staining with varying intensity and distribution in all tumor specimens. Acinic cell carcinoma (n = 5) and polymorphous low-grade adenocarcinoma (n = 1) showed relatively low proliferation fractions. In adenoid cystic carcinoma (n = 13), PCNA-positive nuclei were mainly distributed in neoplastic myoepithelial cells which were the predominant cells in tumor growth. No statistically significant difference was found between cribriformtubular and solid subtypes. In adenocarcinoma (n = 6), a well differentiated papillary-cystic pattern expressed a significantly higher PCNA index than poorly differentiated solid pattern, showing the loss of the relationship between PCNA expression and differentiation. Tumor cell differentiation appears to be more important than proliferation in determining biological behavior and prognosis.