Immunoreactivity of proliferating cell nuclear antigen in salivary gland tumours: an assessment of growth potential.

Immunoreactivity of proliferating cell nuclear antigen (PCNA) was assessed to evaluate growth potential in surgically resected tissue specimens from 70 cases of benign and malignant salivary gland tumours. Three stage streptavidin-biotin immunoperoxidase immunostaining using monoclonal antibody to PCNA showed a heterogeneity of PCNA index and distribution. In normal salivary gland specimens, PCNA was demonstrated in the nuclei of few ductal and acinar cells. In pleomorphic adenoma a multiple nodular growth pattern was observed with positive immunoreactivity restricted to the nuclei of tubulo-ductal structures. Warthin's tumour had positive nuclei in the outer cuboidal cells of epithelial component and germinal centres of lymphoid tissue. Myoepithelioma and acinic cell carcinoma showed slightly differing values and a statistically significant difference in the value of the index was observed in tumour cell aggregates of the cribiform type of adenoid cystic carcinoma and the solid undifferentiated type and between low/intermediate and high-grade mucoepidermoid tumours. PCNA is a useful marker of tumour cell proliferation; the index correlates with the grade of malignancy in salivary gland tumours.