Clinical and histological aspects of malignant inverted sinonasal papilloma. Two case reports.

The inverted sino-nasal papilloma is a benign epithelial lesion, ranging from 1% to 5% of the tumors that reside in this area. It is characterized by a tendency towards local bone destruction, recurrence and malignant transformation. This is a presentation of two cases diagnosed and surgically treated for malignant inverted papiloma, which started in the epithelium of the maxillary sinuses.