Ciliated HPV-Related Carcinoma: A Diagnostic Challenge on Frozen Section.

Oropharyngeal squamous cell carcinomas associated with high risk HPV show a wide morphological spectrum, including papillary, adenosquamous, lymphoepithelioma-like and sarcomatoid. We report an interesting case of ciliated HPV-related carcinoma arising from tonsillar tissue in a 55-year-old man which was associated with HPV33. This rare variant has been described in only a handful of cases in the literature, and to our knowledge this is the first case specifically associated with HPV33. The presence of cilia is a potential diagnostic problem as it has been traditionally considered a feature of benignancy, and could pose a particular challenge on frozen section. The diagnostic challenges, differential diagnosis of this tumor and the association with HPV33 are discussed.