[1129] Clinical HPV Testing in Oral Cavity/Oropharyngeal Squamous Carcinomas of the Head and Neck: Analysis of Site Distribution, Morphology, and Staining Patterns

KA Guggisberg, J Scharpf, D Adelstein, J Saxton, JL Hunt. Calgary Lab Services, Calgary, AB, Canada; Cleveland Clinic, Cleveland, OH

Background: HPV is an important pathogen in head and neck squamous carcinomas (SCC). The relative distribution varies by subsite, with the tonsil/tongue base being more frequently positive. Some studies have suggested basaloid (BSCC) and nonkeratinizing (NKSCC) have higher rates of HPV positivity than keratinizing (KSCC). We perform HPV testing on all oral SCCs. It is not well understood whether HPV is uniformly present in tumors, and whether biopsies are adequate samples for assessing viral presence. Furthermore, the copy number within unique tumor cells has not been studied, particularly with reference to the morphologic subtype of carcinoma.
Design: The surgical pathology files were searched for all reported clinical HPV results for an 18 month period. The site of tumor was recorded (oropharynx vs. oral cavity). The slides were reviewed to assess the relative percentage of KSCC, NKSCC, and BSCC components in the tumors. The HPV ISH was examined for signal (positive vs. negative), distribution of staining (focal vs. diffuse), and staining density (copy number estimation as compared to copy specific positive controls, low vs. high copy number).
Results: 56 cases were reviewed (47 male; 9 female). 46 were from the oropharynx (tonsil/tongue base) and 10 were from oral cavity (oral tongue/floor of mouth). 30/56 cases had mixed morphologies; KSCC predominated in 10, NKSCC in 17, and BSCC in 3 cases. 26 had pure morphology: 12 KSCC, 10 NKSCC, 3 BSCC and 1 LEC. HPV was positive in 29/56 cases (28/46 oropharynx, 1/10 oral cavity). 10/26 histologically pure tumors were HPV positive (1/12 KSCC, 5/10 NKSCC, 3/3 BSCC). 19/30 morphologically mixed tumors were HPV positive (3/11 KSCC predominant, 13/17 NKSCC predominant, and 2/3 BSCC predominant). 19/29 HPV positive cases had diffuse staining while 7 showed focal staining. 5/26 had low HPV copy number in the tumor cells (0/4 KSCC predominant tumors, 2/19 NKSCC predominant, and 3/5 BSCC predominant).
Conclusions: Our clinical experience with HPV assessment in oral SCCs supports prior literature suggesting that HPV is predominantly found in oropharyngeal locations and in BSCC and NKSCC subtypes, whether pure or predominant in mixed tumors. However, we also found HPV in at least 4 tumors that were predominantly keratininizing. Most tumors had high copy number HPV. But, 3/5 of the BSCC predominant tumors had low copy number.
Category: Head & Neck

Monday, March 9, 2009 1:00 PM

Poster Session II # 165, Monday Afternoon