Figure 14: Inverted papilloma of the left maxillary sinus (Krouse stage III). a) Complete opacification of the maxillary sinus by exophytic tumor mass with typical hyperostosis at the small-sized origin at the base of the maxillary sinus (white arrow). b) After resection of the exophytic tumor mass the region of origin is exposed via a prelacrimal approach. Removal of mucosa with 1–1.5 cm safety margins and removal of the bone lying under the tumorattachment. Additional coagulation of an artery of the underlying mucosa of the hard palate. 1 = anterior wall of the maxillary sinus, 2 = region of the removed tumor-affected bone with coagulation after arterial bleeding, 3 = medialized inferior turbinate with nasolacrimal duct. c) Condition after repositioning and fixation of the inferior turbinate. The maxillary sinus can be well accessed via medial maxillectomy for endoscopic control.