Adequacy of fine-needle aspiration specimens for human papillomavirus infection molecular testing in head and neck squamous cell carcinoma

BACKGROUND: Head and neck squamous cell carcinoma is often associated with human papillomavirus (HPV) infection. Positive HPV status has been associated with increased response to treatment and improved prognosis in terms of recurrence-free and overall survival. In certain instances, diagnosis is performed through fine-needle aspiration of lymph nodes with metastatic carcinoma, often demonstrating extensive tumor necrosis. We evaluated the effect of tumor necrosis on deoxyribonucleic acid (DNA) adequacy for HPV molecular testing. MATERIALS AND METHODS: Retrospective review of the pathology files at our institution identified cases of squamous cell carcinoma (SCC) diagnosed by fine-needle aspiration (FNA) on which HPV DNA molecular testing was performed. The cases were classified according to percent tumor necrosis into three categories (<10% necrosis, 10-70% necrosis and >70% necrosis) and the percentage of cases with adequate HPV DNA for molecular testing in each of the categories was compared. When available, p16 immunohistochemistry performed on the cases was compared with HPV status by molecular testing. RESULTS: A total of 70 cases from 67 patients were included in the study. Adequate DNA for molecular HPV testing was obtained from samples of 47 cases (67%) while samples from 23 cases (33%) were inadequate for molecular testing. Of the adequate samples, 36 (77%) were positive and 11 (23%) were negative for high-risk HPV. Adequate DNA for testing was obtained in 22 out of 33 cases showing no necrosis (67%), 10 out of 16 cases showing partial necrosis (63%) and in 13 out of 17 cases showing extensive necrosis (76%). CONCLUSION: Our study found that HPV molecular testing is not influenced by percent tumor necrosis or method by which FNA was performed. We believe that a portion of the FNA specimen obtained from head and neck lesions diagnosed as SCC during the rapid on-site evaluation should be sent for HPV DNA testing, independent of the amount of tumor necrosis, thus guaranteeing availability of specimen for HPV testing.