An algorithm for the judgment of high-risk HPV association with oropharyngeal carcinoma. Cases positive for both p16 IHC and ISH were judged as high-risk HPV-associated oropharyngeal carcinoma (HPV-OPC). ISH specific for type 16/18 HPV was conducted for all cases. Cases discordantly p16 positive by IHC but HPV16/18 negative by ISH were further evaluated for wide-spectrum HPV types (types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, and 68). Number of cases corresponding to each is shown in parentheses.