Significance of Epstein-Barr virus and Human papillomavirus type 16 in the development of pleomorphic adenomas of the salivary glands

Abstract

Aim: The aim of the study was to determine the role of Epstein-Barr virus and human papillomavirus (HPV) type 16 in the development of pleomorphic adenoma of the salivary gland by identifying the viruses in tumor tissue, oral mucosal epithelium, oral fluid, and blood. Materials and Methods: The study included 30 patients with a morphologically confirmed diagnosis of pleomorphic adenoma of the parotid salivary glands, who were assigned to group 1. The control group (group 2) consisted of 10 patients who had no tumor or non-tumor salivary gland pathology either during life or at autopsy examination. To identify Epstein-Barr virus and HPV type 16, an immunohistochemical examination of tumor tissue fragments in group 1 and salivary gland tissue fragments in group 2 was performed, as well as polymerase chain reaction (PCR) analysis of blood, buccal scraping, and oral fluid. Statistical analysis of the obtained data was performed using the PAST software (version 4.15, Natural History Museum, University of Oslo, Norway). Mean values of indicators were compared using the Mann-Whitney U test. Results: The immunohistochemical reaction with mouse monoclonal antibody (MMA) to HPV type 16 was positive in a significantly greater (p<0.05) number of cases in group 1 (26 cases, 86.7%) compared with group 2 (3 cases, 42.9%). The number of cases with a positive immunohistochemical reaction with MMA to anti-Epstein-Barr virus was significantly higher (p<0.05) in group 1 (8 cases, 26.7%) compared with group 2 (1 case, 14.3%). PCR study of buccal scraping, blood and oral fluid samples from patients in group 1 revealed a lower number of cases with a positive reaction compared with the immunohistochemical examination of tumor tissue. In group 2, this analysis did not detect any positive cases at all. In group 1 PCR enabled the detection of Epstein-Barr virus DNA in buccal scraping in 2 cases, accounting for 6.7%; in oral fluid samples in 4 patients (13.3%); in blood samples in 4 patients (13.3%). The study of buccal scraping, oral fluid and blood by PCR in patients from group 1 enabled the detection of HPV type 16 DNA, respectively, in 1 case (3.3%), 2 cases (6.7%), 2 cases (6.7%). Conclusions: HPV type 16 appears to play a greater role in the genesis of pleomorphic adenomas of the parotid salivary glands compared with Epstein-Barr virus. Immunohistochemical examination of tumor tissue is an effective method for demonstrating the role of HPV type 16 and Epstein-Barr virus in the development of pleomorphic adenomas of the salivary glands. PCR analysis of oral fluid, blood, and buccal scraping is not a sufficiently sensitive or reliable method for identifying the investigated viruses in patients with pleomorphic adenomas.