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 |
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