Spindle cell carcinomas of the head and neck rarely harbor transcriptionally-active human papillomavirus

Spindle cell carcinoma is an uncommon variant of squamous cell carcinoma characterized by spindled or pleomorphic cells which appear to be a true sarcoma but are actually epithelial. Some head and neck squamous cell carcinoma variants can be human papillomavirus (HPV)-related and have improved outcomes. We sought to determine if spindle cell carcinomas are associated with transcriptionally-active HPV. Cases of spindle cell carcinoma were retrieved from department files. Transcriptionally-active HPV was determined by mRNA in situ hybridization for high risk HPV E6 and E7 transcripts and by a surrogate marker, p16 immunohistochemistry, with a 50% staining cutoff. RT-PCR for high risk HPV mRNA was performed on the cases that were technical failures by in situ hybridization. Medical records and follow up information were retrieved for all patients. Of 31 cases, 5 were from the oropharynx, 12 from the oral cavity, and 14 from the larynx or hypopharynx. One purely spindled oral cavity spindle cell carcinoma was HPV positive. It was also diffusely positive for p16. Another laryngeal spindle cell carcinoma was HPV positive in both the squamous and spindle cell components, but was negative for p16. None of the five oropharyngeal spindle cell carcinomas were positive for p16 or HPV RNA. The HPV positive patients both presented at high stage (IV) and died with disease within 2 years of diagnosis. The majority of spindle cell carcinomas of the head and neck, including those arising in the oropharynx, are not related to transcriptionally active HPV. Although the number of cases is too small for any definitive conclusions, for the rare HPV positive spindle cell carcinoma cases, positive viral status does not appear to confer any prognostic benefit.