Background: A considerably large portion of the cases of cancer, particularly squamous cell carcinoma (SCC) involving the head and the neck may be due to consumption of tobacco and alcohol. However, its increase in occurrence at specific sites of the head and neck may indicate the possibility of other etiological factors. One of which is infection by certain high-risk human papillomavirus (HPV). P16 immunochemistry serves as a very good surrogate marker of active HPV in these tumors. The detection of HPV-related head and neck cancers have relevance in clinical practice because of its prognostic implications. Objectives: The general objective of this study is to determine the prevalence of p16-positive squamous cell carcinoma in the oral cavity, oropharynx, and larynx in Rizal Medical Center from January 2019 to December 2019. The specific objective is to compare the Hematoxylin and Eosin (H&E) stain histomorphology (keratinization and mitotic activity) of p16-positive versus p16-negative specimens. Methodology: This is a cross-sectional study which included all routine histopathology specimens coming from the oral cavity, oropharynx and larynx in Rizal Medical Center for the year 2019 with a diagnosis of squamous cell carcinoma. The tissue specimens considered were those that measured at least 1 cm in diameter, or aggregate diameter if tissue is fragmented. The slides of all eligible cases were reviewed and immunohistochemically stained for p16. The p16 IHC slides were read as either positive or negative, while the mitotic activity and keratinization were observed in the H&E-stained slides. The interpretation of the diplomate pathologists for each of the slides were documented and corresponding statistical analyses were performed. Results: P16 IHC showed twenty-one (88%) p16 negative cases and three (12%) p16 positive cases. In terms of mitosis, ten cases have mitosis falling within the 1-10 per high power field (HPF) range (42%), six within 11-20 per HPF (25%), and 8 cases have ≥21 mitosis per HPF (33%). In terms of keratinization, three cases are non-keratinizing (12%) and twenty-one cases are keratinizing (88%). There is significant difference in the keratinization histology (p<0.05) of the p16-positive versus the P16-negative cases. On the other hand, no significant difference in the mitotic activity (p>0.05) was noted. Conclusion There is a low prevalence of HPV-related SCC of the oral cavity, oropharynx, and larynx in Rizal Medical Center. The histomorphologic findings confirm that keratinization, significantly predicts HPV status in oropharyngeal SCC. Mitotic activity may not be reliable in predicting the HPV status or p16 IHC reactivity of a case. Keratinization in oropharyngeal SCCs may provide valuable information in certain instances, particularly when HPV testing is not immediately available, although the combined tumor morphology and p16 IHC is more ideal.
Papillomavirus Infections ; Squamous Cell Carcinoma of Head and Neck ; Mouth ; Larynx