Original paper ASSESSMENT OF BONE INVOLVEMENT AND MALIGNANCY IN SINONASAL INVERTED PAPILLOMAS

Introduction - Sinonasal inverted papilloma (IP) is a rare benign epithelial neoplasm of unknown etiology characterized by destructive pattern of local growth, tendency to recur after surgery and associated squamous cell carcinoma. The aim of this study was to evaluate the bone erosions and the malignant transformation in sinonasal inverted papilloma. Material and methods - The presence of bone erosions and the association to squamos cell carcinoma, were analysed in 43 patients with histologically proven inverted sinonasal papilloma. All patient data were retrospectively staged using the staging system for inverted papilloma proposed by Krouse. Results - The study group consisted of 28 men and 15 women, confirming the male predominance. 25 patients (58.2%) were admitted with a stage II inverted papilloma. Eight patients (18.6%) were admitted with extranasal inverted papilloma, extension beyond the sinuses or even malignant transformation, representing stage IV inverted papillomas. In ten cases (23.2%) localized bone defects were found on the preoperative CT scans as well as intraoperatively. Histological examination revealed inverted papilloma with focal transformation to squamous cell carcinoma in five cases (11.6%). Discussion and Conclusions - Although benign, inverted papilloma has an aggressive clinical behavior. Even in the absence of malignancy, the adjacent bone destructions are not uncommon. Close follow-up after surgical removal is necessary and extremely important to detect early recurrence or possible transformation to malignancy.