Screening for HPV in Clinically Benign Tonsillectomy Specimens
Jessica B Bekker, Mark F Evans, Kirsten J Threlkeld, Vanitha Rajendran, Christine S Adamson, Kumarasen Cooper. University of Vermont, Burlington, VT
Background: The incidence of oropharyngeal squamous cell carcinoma is rising, as is the proportion of these tumors with detectable human papillomavirus (HPV). Viral etiology confers an improved prognosis as these tumors respond better to standard treatment when compared to HPV negative tumors. Many studies have evaluated the prevalence of HPV in tonsillar carcinomas, but few have investigated the prevalence of HPV in benign tonsils. We report our experience measuring the prevalence of HPV in non-neoplastic tonsillar tissue of patients 30 years and older.
Design: Two hundred tonsillectomy cases from adults aged 30 years and older were retrospectively reviewed from 2008 - 2010, each with a benign clinical indication for surgery. A review of patient medical records showed no preoperative suspicion of malignancy in any case. Immunohistochemical staining for p16INK4a was performed on all cases as a marker for HPV infection. Confirmatory PCR and in-situ hybridization (ISH) for HPV was performed on all cases with positive p16 staining as well as cases with incidental dysplasia or carcinoma.
Results: Three specimens contained incidental squamous cell carcinoma and/or high grade dysplasia (1.5%). Two of these tested positive for HPV, exhibiting strong, diffuse, nuclear and cytoplasmic p16 staining, confirmed by PCR and ISH. Of 197 cases with benign histology, all were negative for p16.
Conclusions: The prevalence of incidental malignancies and pre-malignancies in this study is much higher than previously reported, supporting the role of routine histological examination of tonsillectomy specimens in adults. Conversely, the presence of positive p16 staining in the absence of malignancy is much lower than previously reported; therefore testing should be reserved for cases with dysplastic or neoplastic epithelial changes.
Category: Head & Neck
Wednesday, March 21, 2012 9:30 AM
Poster Session V # 187, Wednesday Morning