Pharyngeal squamous cell papilloma in adult Japanese: comparison with laryngeal papilloma in clinical manifestations and HPV infection

A number of reports have investigated the relationship between laryngeal papilloma and human papilloma virus (HPV) infection. On the other hand, it is unclear whether the HPV infection is involved in the occurrence of pharyngeal papilloma. We hypothesized that HPV infection was involved in the occurrence of pharyngeal papilloma similarly to laryngeal papilloma. To verify this hypothesis, we investigated the presence of HPV infection. Furthermore, clinical manifestations of pharyngeal papilloma, which had rarely been reported, were discussed. A male-to-female ratio, solitary or multiple occurrences, and koilocytosis were examined in cases with pharyngeal papilloma. HPV DNA was examined with unfixed surgically resected specimens of pharyngeal papilloma. A screening test by the liquid-phase hybridization method was carried out for the HPV high-risk group (16, 18, 31, 33, 35, 39, 45, 51, 56, 58, 59, and 68) and HPV low-risk group (6, 11, 42, 43, 44). As a control, 15 cases with laryngeal papilloma for which the same screening test was carried out were employed. Pharyngeal papilloma occurred as a solitary lesion more often, whereas laryngeal papilloma occurred as multiple tumors more frequently. The HPV infection rate was 0% in pharyngeal papilloma cases, which was in stark contrast with 66.7% in the HPV low-risk group in laryngeal papilloma cases. Pharyngeal papilloma occurred as a solitary lesion in females more frequently. Contrary to our hypothesis, the involvement of HPV infection was unlikely in the occurrence of pharyngeal papilloma.