P16INK4A immunostaining is a strong indicator for high‐risk‐HPV‐associated oropharyngeal carcinomas and dysplasias, but is unreliable to predict low‐risk‐HPV‐infection in head and neck papillomas and laryngeal dysplasias

Human papillomavirus (HPV) is a risk factor for the development of benign and malignant mucosal head and neck lesions. P16 INK4A is often used as a surrogate marker for HPV‐infection, although there is still controversy with respect its reliability. Our aim was to determine if p16 INK4A overexpression can accurately predict both high‐risk and low‐risk‐HPV‐presence in (pre)malignant and benign head and neck lesions. P16 INK4A immunohistochemistry was performed on paraffin‐embedded tissue sections of 162 oropharyngeal squamous cell carcinomas (OPSCC), 14 tonsillar and 23 laryngeal dysplasias, and 20 tonsillar and 27 laryngeal papillomas. PCR, enzyme‐immunoassay and FISH analysis were used to assess HPV‐presence and type. Of the 162 OPSCC and 14 tonsillar dysplasias, 51 (31%) and 10 (71%) were HPV16‐positive, respectively. All tonsillar papillomas were HPV‐negative and four laryngeal dysplasias and 26 laryngeal papillomas were positive for HPV6 or −11. P16 INK4A immunohistochemistry revealed a strong nuclear and cytoplasmic staining in 50 out of 51 HPV16‐positive and 5 out of 111 HPV‐negative OPSCC ( p < 0.0001) and in all HPV16‐positive tonsillar dysplasias, whereas highly variable staining patterns were detected in the papillomas and laryngeal dysplasias, irrespective of the HPV‐status. In addition, the latter lesions generally showed a higher nuclear than cytoplasmic p16 INK4A immunostaining intensity. In conclusion, our data show that strong nuclear and cytoplasmic p16 INK4A overexpression is a reliable surrogate indicator for HPV16 in OPSCC and (adjacent) dysplasias. For HPV6 or −11‐positive and HPV‐negative benign and premalignant lesions of the tonsil and larynx, however, p16 INK4A immunostaining is highly variable and cannot be recommended to predict HPV‐presence.