Proliferative activity as detected by immunostaining with Ki-67 and proliferating cell nuclear antigen in benign and malignant epithelial lesions of the human parotid gland

OBJECTIVE: A retrospective immunohistochemical study of parotid gland lesions was designed to evaluate the diagnostic and prognostic value of the proliferating cell nuclear antigen (PCNA) and Ki-67 with monoclonal antibodies PC 10 and MIB-1, respectively. STUDY DESIGN: Tissue samples comprised normal parotid gland (N, n=10), chronic sialadenitis (CS, n=8), Warthin's tumor (W, n=10), benign pleomorphic adenoma (BPA, n=8), mucoepidermoid carcinoma (MEC, n=13), carcinoma in pleomorphic adenoma (CPA, n=8) and adenoid cystic carcinoma (ACC, n=12). The morphometric parameters for PCNA and MIB-1 comprised the PI and MI labelling indices (the numerical percentage of positive nuclei), N-AP and N-AM (the numerical density of positive nuclei), and NPI and NMI (volume corrected index). RESULTS: The values of MIB-1 parameters increased progressively in benign lesions in comparison with the N group and in malignant neoplasms in comparison with nonneoplastic groups and benign lesions. Values for all parameters in BPA were significantly lower than those in malignant groups. Spearman rank correlation analysis showed a highly positive correlation between the morphometric parameters and severity of the lesions. The mean values of MI and NMI were significantly higher in patients who died of the malignant tumors than in those mho survived. The same quantitative parameters for PCNA did not differ significantly from those obtained for MIB-1 and showed similar trends. CONCLUSION: PCNA and MIB-1 indices are reliable markers for discriminating between benign and malignant tumors of the parotid gland, and the parameters PI, MI, NPI and NMI may have prognostic applications.