Probes for P16

Detection of human papilloma virus (HPV)-related head and neck squamous cell carcinoma (HNSCC) is important, as HPV-associated HNSCCs respond better to therapy. The RNAscope HPV-test is a novel RNA in situ hybridization (ISH) technique which strongly stains transcripts of E6 and E7 mRNA in formalin-fixed, paraffin-embedded tissue, with the potential to replace the indirect immunohistochemical (IHC) marker for p16 protein. A direct clinical comparison between p16 IHC and an automated RNA ISH using 18 probes has not been established. Samples from 27 formalin-fixed, paraffin-embedded HNSCC cases from the Emory University Hospital archives were stained using 18 individual RNA ISH probes for high-risk HPV (RNAscope 2.5 LS Probe ) on a Leica autostainer (Buffalo Grove, IL) and were compared with p16 IHC. Two pathologists reviewed and reached a consensus on all interpretations. The RNAscope technique was positive in 89% (24/27) and the p16 IHC was positive in 78% (21/27). The RNAscope was negative in 11.1% of samples (3/27) and the p16 IHC-negative in 22.2% (6/27). The RNA ISH detected 100% of the p16-positive IHC-stained slides and had a concordance of 88.9% (24/27). This easy to interpret automated staining method for 18 high-risk HPV genotypes is a feasible replacement for the indirect p16 IHC method.

HPV-related multiphenotypic sinonasal carcinoma (HMSC) is associated with high-risk human papillomavirus (HR-HPV) infection. Using HR-HPV mRNA in situ hybridization (ISH), we reported six new HMSC cases and compared their histopathology with that of sinonasal adenoid cystic carcinoma (ACC). Using p16 immunohistochemistry (IHC) and HR-HPV ISH, we retrospectively identified six HMSC cases. All HMSC cases were positive for HR-HPV mRNA ISH and p16 IHC. Two HMSC cases had overlying atypical squamous epithelium and one also had invasive squamous cell carcinoma (SCC). All HMSC were SOX10-positive whereas the overlying atypical squamous epithelium and the SCC were SOX10-negative. One atypical HMSC-like case was also identified which was positive for HR-HPV mRNA ISH, HR-HPV DNA ISH, SOX10 IHC, but negative for p16 IHC. This study showed that HR-HPV mRNA ISH was a useful tool to diagnose HMSC and had stronger signals than HR-HPV DNA ISH. HR-HPV E6/E7 mRNA could be identified in the overlying atypical squamous epithelium as well as the invasive SCC. A combination of p16 and SOX10 IHC will be a useful screening panel for HMSC followed by confirmatory HR-HPV mRNA ISH test.