Coinfection of HPV-11 and HPV-16 in a case of laryngeal squamous papillomas with severe dysplasia

Human papillomavirus (HPV) types 6 and 11 have been associated with benign laryngeal papilloma, while HPV-16 is occasionally associated with laryngeal carcinoma. In this study, a case of laryngeal squamous papillomas with severe dysplasia was evaluated for the presence of HPV infection. The biopsy specimens were taken from a 58-year-old female patient at two different time points 3 months apart. Architecturally, the tumor showed papillary configuration reminiscent of squamous papilloma. Cytologically, the lesion showed morphologic features characteristic of severe squamous epithelial dysplasia. HPV infection was determined by DNA in situ hybridization using type-specific HPV-DNA probes. HPV-11 probes demonstrated homogeneous nuclear staining, suggesting productive viral replication. In contrast, HPV-16 probe produced a speckled pattern, suggesting HPV-16 DNA integration. Normal laryngeal epithelium did not yield specific hybridization. The presence of HPV-11 and HPV-16 was confirmed by PCR using HPV type-specific primers. Immunocytochemical staining was performed to detect Ki-67, a proliferation marker, and p53. Ki-67 expression was demonstrated throughout the whole thickness of epithelium. Staining for p53 was negative. This study suggests that multiple HPV infections can occur in the same lesion and that HPV-16 infection and its DNA integration may contribute to the occurrence of severe dysplasia in the lesion described.