Background: Inverted papillomas are primarily benign neoplasms that occur in the nasal cavity and paranasal sinuses. Many aspects of sinonasal inverted papillomas are still controversial and active fields of research. Inverted papillomas generate considerable interest because they are locally aggressive, have a propensity to recur and are associated with malignancy. However, neither the etiology and pathogenesis of these tumors nor the putative role as a precursor to carcinoma and the factors responsible for associated malignancy have been clarified. Whether carcinomas in inverted papillomas arise meta- or synchronous is also still unknown.
Patients and methods: In a retrospective study we reviewed the charts of 93 patients with sinonasal inverted papillomas who were treated at our department between 1990 and 2007. Comparison was made between the group of patients with inverted papillomas and associated squamous cell carcinomas and the group of patients with benign inverted papillomas. We undertook a critical analysis of our results compared with the international medical literature.
Results: Associated malignancy was found in 11 patients (11.8 %). In each one case a metachronous carcinoma with and without recurrent inverted papilloma was diagnosed, the remaining 9 carcinomas were determined to be synchronous malignancies. Our data suggest, that the association between carcinoma and inverted papilloma is indirect and that the gradual progression from inverted papilloma to a malignant neoplasm is if at all infrequent. Male gender, advanced age and recurrent inverted papilloma do not per se present risk factors for the development of associated malignancies.
Conclusions: Sinonasal carcinomas arise in about 10 % of patients with inverted papillomas, but the ratio of metachronous carcinomas has possibly been overrated up to now. Nevertheless, regular follow-up investigations after surgical resection of inverted papillomas are mandatory. The assumption, that carcinomas in inverted papillomas are less aggressive than carcinomas alone and the definition of high-risk groups for the development of carcinomas seems hazardous.