Expression of Ki-67 antigen and proliferative cell nuclear antigen in benign and malignant epithelial lesions of the larynx.

In an attempt to analyse the proliferative activity in benign and malignant laryngeal epithelial lesions, and to determine the relationship to their histologic grade, we studied the expression of proliferative cell nuclear antigen (PCNA) and Ki-67 antigen on 20 squamous carcinomas, and on 30 biopsies of epithelial hyperplasia categorized according to the Kambic-Lenart classification into simple, abnormal, and atypical hyperplasias. In simple hyperplasia, both antibodies stained the nuclei of the occasional cells in the basal layer. In abnormal hyperplasia (mild dyplasia), positive cells occupied up to a third, and in atypical hyperplasia (moderate and severe dysplasia) they occupied from two-thirds to the entire epithelial thickness. In squamous carcinoma, we have found a statistically significant correlation between its grade and the percentage of Ki-67-(p < 0.01) and PCNA-(p < 0.00001) positive cells. Our results suggest that the proliferative fraction progressively increases with the degree of epithelial hyperplasia and the grade of carcinoma. We conclude that the patterns of immunoreactivity to PCNA and Ki-67 antigen correspond to the histologic grade of both benign and malignant epithelial lesions of the larynx. This method should be regarded as a useful adjunct to traditional histological techniques allowing more objective grading of benign and malignant epithelial lesions.