Background: Recurrent respiratory papillomatosis (RRP) is caused by human papilloma virus (HPV) and is the most common benign laryngeal neoplasm in children. Although RRP is rarely fatal, the disease requires prolonged, extensive medical and surgical treatment, leading to physical and emotional suffering in affected children and their families. Previous studies show HPV type 11 and type 6 in the lesion of Thai subjects with RRP. There is currently no published data available from Thailand that compares staging and severity with RRP genotypes.
Objective: To identify the genotypes of human papilloma virus (HPV) isolated from patients with RRP and compare the staging and severity with human papilloma virus genotype.
Material and Method: This prospective study was designed to assess population characteristics and follow the clinical course of RRP from January 2011 to January 2013. At each endoscopic evaluation or debridement, all surgeons to stage each patient’s disease severity used a consistent scoring system. The samples were analyzed for HPV genotype.
Results: Fifteen Thai children (7 female, 8 male) with respiratory papillomatosis were enrolled. Results showed that HPV type 6 and HPV type 11 caused RRP in 6 (40%) and 9 (60%) of the children, respectively. No co-infection between HPV type 6 and type 11 was found. Overall mean age at diagnosis of patients with RRP was 2.65+0.82 years. The age at diagnosis was significantly different between both HPV genotypes (p = 0.008). The mean disease severity score for HPV type 6 infection was 13.83+9.94, and that of HPV type 11 infection was 27.44+8.24. The mean disease severity score of HPV type 11 infection was significantly higher than that of HPV type 6 infection (p = 0.013).
Conclusion: HPV type 6 and type 11 caused RRP in Thai children. RRP attributable to infection with HPV type 11 is more aggressive in disease severity and has a shorter life time than HPV type 6 at time of first diagnosis. RRP is an incurable disease that requires long-term medical management. Improved awareness and understanding amongst the Thai population should be promoted to limit the spread of the disease. In addition, further research on the treatment of RRP would benefit patients.

Keywords: Recurrent respiratory papillomatosis, Human papilloma virus, Human papilloma virus genotype