Background: Tumor-related high risk human papillomaviruses (HPV) 16 and 18 have been repeatedly detected in head and neck cancers, particularly, they are well known risk factors in squamous cell carcinoma of the oropharyngeal and tonsillar region. Little is known, however, about the possible role of HPV in salivary gland tumors.
Methods: Fifty-five cases of benign and malignant salivary gland tumors were tested using p16 immunohistochemistry followed by HPV DNA polymerase chain reaction (PCR) using SPF, CPSGB, GP5+/GP6+ primers, and type specific primers for HPV 16, 18, 31, 33, 35, 45 in the cases with strong immunohistochemical expression for p16 protein (score 3+).
Results: Only 5 tumors of 55 (9 %) were completely devoid of any p16 staining, and in 10 cases (18 %), less than 25 % of tumor cells stained (score 1+). In the majority of cases (35 of 55; 64 %) there was a patchy nuclear and cytoplasmic strong staining in 26 to 50 % of tumor cells (score 2+). In five cases (9 %), strong nuclear and cytoplasmic staining in more than 51% of tumor cells was detected (score 3+). However, none of the p16-positive cases showed any evidence of high-risk HPV by PCR.
Conclusions: The results of the study indicate that HPV, in particular oncogenic types 16 and 18, are not involved in the etiology of benign and malignant epithelial tumors of salivary glands. Therefore, it is likely that salivary gland tumors belong to the category of tissues in which the p16 positive immunohistochemistry is not biologically relevant to the oncogenic role of HPV infection.