Automated and manual human papilloma virus in situ hybridization and p16 immunohistochemistry: comparison in metastatic oropharyngeal carcinoma.

OBJECTIVES We compared the efficacy of automated and manual human papilloma virus (HPV) in situ hybridization (ISH) and p16 immunohistochemical staining (IHC) in fine needle aspiration (FNA) of metastatic oropharyngeal carcinoma. STUDY DESIGN A total of 41 FNA cell blocks (CB) were evaluated. HPV ISH was interpreted as positive if a minimum of one tumor cell showed punctate dot-like nuclear positivity. p16 was interpreted as positive if ≥70% of tumor cells showed brown nuclear and cytoplasmic staining. RESULTS Thirty of 41 CB (73%) were positive by automated HPV ISH, 25 of 41 CB (60%) with manual HPV ISH. Eighteen of 41 CB (43%) were positive for p16 IHC. Twelve of 41 CB (29%) with automated HPV ISH and 2 of 41 CB (4%) with the manual method were positive at 10× magnification. Three of 41 CB (7%) with automated HPV ISH and 14 of 41 CB (34%) with the manual method were positive at 20× magnification. Fifteen of 41 CB (36%) with automated HPV ISH and 9 of 41 CB (21%) with the manual method were positive at 40-60× magnification. CONCLUSION Automated HPV ISH plays a more significant role in determining the HPV status in CB. However, the failure to use high magnification in the evaluation can give false-negative results.