INTRODUCTION
Inverted papilloma (IP) is a benign epithelial tumour composes of well-differentiated columnar or ciliated respiratory epithelium having variable squamous differentiation. The incidence of IP approximately 0.2 to 0.6 per 100,000 population per year.1 They most commonly arise from the lateral nasal wall (90%) with frequent extension into the maxillary, anterior, and posterior ethmoid sinuses.2 They are typically unilateral (95%). There are three main clinical characteristics that attribute the tumours which have a tendency to recur (16-60%), their destructive capacity to surrounding structures and their propensity to be associated with malignancy (5-13%).3 IP occurs predominantly in male patients, with a male to female ratio of 3:1. The age range of presentations extends from the second to the seventh decade of life. The mean age at the time of clinical presentation is nearly 50 years.4
HPV is a small double stranded DNA virus which is approximately 8Kbp in size. They are associated with specific mucosal and epithelial lesions ranging from benign proliferative lesions to invasive carcinomas. Approximately 120 genetically distinct types of human papillomaviruses have been identified, and the genomes of more than 80 have been completely sequenced.5  Benign lesions are usually associated with low risk types of HPV which are the Type 6 and 11.6 HPV types 16 and 18 are classified as the high-risk types and are commonly associated with malignant lesions. All the identified types of HPV have appeared to be only epitheliotropic and infect the mucosal or cutaneous epithelium of the anogenital tract or upper respiratory tract.7. PCR-based detection of HPV E6 oncogene expression in frozen tissue samples is generally regarded as the gold standard for establishing the presence of HPV.8
The recurrence and malignant transformation of nasal inverted papillomas were related to HPV infection.9 The presence of this virus may play a role in the biological behaviour of these epithelial proliferations. In a meta-analysis of 1041 sinonasal papilloma analysed for HPV, 347 (33.3%) cases were positive.10 However, the association between HPV infection and IP is still not universally acceptable due to the high disparate rates of HPV detection of between 0–79%.2 Due to this great variance, it was our aim to determine the prevalence of HPV in sinonasal inverted papilloma, to correlate the HPV genotypes with recurrence of disease and to correlate the HPV genotypes with malignant transformation.