WOS: 000264851900041Inverted papilloma (IP) is a benign tumor characterized with basal cell hyperplasia and epithelial invasion into the stroma. IP frequently originates from lateral nasal wall, middle turbinate and middle meatus, and rarely from paranasal sinuses. IP can histologically be with different degrees of atypia, dysplasia, carcinoma in situ and carcinoma. Mucoceles are chronic and cystic lesions of the paranasal sinuses formed by chronic obstruction of the sinus ostia due to inflammation, scar formation, osteoma and tumor. Frontal mucoceles are formed by the obstruction of the nasofrontal canal. In this article, two cases of inverted papillomas were presented. In the first case, IP caused mucocele, which had invaded into the orbita leading to proptosis by obstruction of the nasofrontal recess, and had eroded the inferior wall of the frontal sinus. In the other case, squamous cell carcinoma had developed. This article discussed the two cases in the light of the literature
