Use of in situ hybridization for HPV in head and neck tumors: experience from a national reference laboratory

The human papillomavirus (HPV) status of head and neck squamous cell carcinomas (SCCs) is a frequent request for Anatomic Pathology labs. However, prognostic value of HPV status is limited to identification of high risk HPV in oropharyngeal SCCs. The purpose of this study is to investigate the ordering practices of in situ hybridization (ISH) for HPV in head and neck tissues at our national reference laboratory. All testing orders for low risk, high risk, and combined low and high risk HPV-ISH tests requested at ARUP Laboratories between January 2010 and November 2013 had their results reviewed and were grouped by anatomic location of the tested tissue. The H&E and HPV-ISH slides from a sample of the most recent 123 tests were reviewed by two pathologists. A total of 1,128 HPV-ISH tests were ordered during the study period. Testing for combined low and high risk HPV was the most commonly ordered test. The positivity rate for high risk HPV was highest in oropharyngeal tissues. 49 of 123 reviewed cases had testing requested on non-malignant tissue, 11 of which were non-neoplastic. Unnecessary HPV-ISH ordering is prevalent in head and neck tissues. Dual testing for low and high risk HPV, frequent testing outside of the oropharynx, and testing non-neoplastic tissues appear to be common practices.