Table 1: Comparing IP to other Schneiderian papilloma.

Papilloma Fungiform Inverted Oncocytic Schneiderian Former name/synonyms Septal Ringertz Cylindrical, columnar Prevalence % 50 47 3–5 Origin Nasal septum Lateral nasal wall and paranasal sinuses Lateral nasal wall and paranasal sinuses Epithelium pattern of growth Everted, exophytic Infolded, endophytic   Microscopy Thick squamous epithelium and, less frequently, respiratory epithelium arranged in papillary fronds Thickened squamous epithelium admixed with mucocytes and intraepithelial mucous cysts Multilayered epithelium with an eosinophilic cytoplasm among which intraepithelial mucin cysts Age group Younger 50~60 30~80 Malignancy 35% have invasive squamous cell carcinoma Locally aggressive, extending into the sinuses, the orbit, nasopharynx [20], or meninges. Three to 24% (mean 13%) may have an invasive focus of squamous cell carcinoma 14%~19% Malignant change potential   25% multifocal   Mixed with typical inverted papilloma