Background: Distinguishing branchial cleft cysts (BCCs) from cystic metastases of a human papillomavirus (HPV) positive oropharyngeal squamous cell carcinoma (OPSCC) is challenging. Fine needle aspirates (FNAs) from cystic metastasis may be non-representative, while reactive squamous cells from BCC can be atypic. Based on cytology and with the support of HPV DNA positivity many centers treat cystic metastasis oncological and thus patients are spared neck dissection. To do so safely, one must investigate whether HPV DNA and p16INK4a overexpression is found exclusively in cystic metastases and not in BCC.
Patients and methods: DNA was extracted from formalin fixed paraffin embedded (FFPE) surgically resected BCCs from 112 patients diagnosed 2007-2015 at Karolinska University Hospital and amplified by PCR. A multiplex bead-based assay used to detect 27 HPV-types and p16INK4a expression was analyzed by immunohistochemistry (IHC).
Results: All 112 BCCs were HPV DNA negative, and of 105 BCCs possible to evaluate for p16INK4a, none overexpressed p16INK4a.
Conclusions: HPV DNA and p16INK4a overexpression were absent in BCCs. Lack of HPV DNA and p16 protein overexpression in BCCs is helpful to discriminate benign BCCs from HPV+ OPSCC metastasis. HPV testing definitely has a role in the diagnostics of cystic masses of the neck.
Keywords: HPV; base of tongue cancer; branchial cleft cyst; oropharyngeal cancer; prevalence; tonsillar cancer.