Human papillomavirus testing in diagnostic head and neck histopathology

Assessment of human papillomavirus (HPV) status is a requirement for the diagnosis of HPV-associated oropharyngeal squamous cell carcinoma (OPSCC) and metastatic squamous cell carcinoma in cervical lymph nodes where the location of the primary neoplasm is unknown. Within the diagnostic histopathology laboratory, there should be a validated and reproducible HPV testing strategy that can provide HPV status within a reasonable timeframe to inform patient care. Although these requirements are recognized by the head and neck oncology community, there is no internationally accepted standard for HPV testing. A two-tiered approach incorporating p16 immunohistochemistry with specific HPV testing by DNA in situ hybridization is a pragmatic way of providing HPV testing in clinical practice. A novel RNA in situ hybridization methodology targeting E6 and E7 mRNA has been validated and is likely to be available as an in vitro diagnostic device soon. This review will outline the current concepts around the diagnosis of HPV-associated head and neck SCC and suggest a diagnostic algorithm that can be instituted in most diagnostic cellular pathology laboratories.