Current advances in the basic research and clinical management of sinonasal inverted papilloma (review).

Inverted papilloma (IP) is a benign sinonasal lesion that has a known propensity for recurrence, local aggressiveness and an association with transformation to squamous cell carcinoma. Due to the high rate of recurrence, association with malignancy and a tendency of multicentricity, the surgical approaches to treatment are controversial. Over the years there has been a slow evolution from aggressive (en bloc) resection by lateral rhinotomy to endoscopic techniques. This progress corresponds to the advances that have been made in endoscopic sinus surgery over the past 15 years. Technological advances have allowed the detection of sinonasal IP before its extension beyond the sinonasal region, thus enabling minimally invasive techniques to be used in the treatment of selected cases of IP. Differences in recurrence rates were not observed for endoscopic management as compared with lateral rhinotomy or sublabial degloving approaches. In terms of aetiology there is certain evidence that the presence of HPV in IP could be predictive of malignant transformation. Although IPs are monoclonal proliferations, they do not fit the profile of a prototypic precursor lesion. In contrast, an increased EGFR and TGF-alpha expression is associated with early events in IP carcinogenesis. Parameters such as hyperkeratosis, squamous epithelial hyperplasia and a high mitotic index are negative prognostic indicators, which could be useful in the future follow-up of patients with IP. Present literature should encourage us to recommend the use of a uniformly accepted staging system. The propensity for delayed recurrences and the maximal 13% incidence of malignant transformation mandates careful, long-term follow-up.