There are 3 histologic subtypes:
Inverted papillomas (IP) represent the majority of SP and typically occur during the fifth decade of life. They characteristically originate from the lateral nasal wall or paranasal sinuses. Underlying human papillomavirus (HPV) infection is implicated in up to 40% of cases.
Exophytic papillomas (EP), also known as fungiform or septal papillomas, are the second most common type of SP and are usually found in men between the ages of 20 and 50. They usually originate from the anterior nasal septum and are rarely found in the paranasal sinuses. Risk factors include chronic rhinosinusitis and smoking. EP have also been linked to HPV, with one study citing evidence for underlying Epstein-Barr virus (EBV).
Oncocytic papillomas (OP) are the rarest subtype. They are found equally among the sexes and usually appear after age 50. They are only found in the lateral nasal wall and ethmoid and maxillary sinuses.
Presenting symptoms of SP include nasal obstruction, epistaxis, frontal headache, and rhinorrhea. Pain is rare and may represent secondary infection or malignant transformation. SP, especially EP, may be asymptomatic and found incidentally. SP with orbital involvement via bone erosion or invasion can cause proptosis, visual loss, and diplopia.
About 3% of SPs undergo malignant transformation, usually to squamous cell cancer. The risk of malignant transformation is very low in EP and higher (up to one-fourth of cases) in IP and OP.
D14.0 – Benign neoplasm of middle ear, nasal cavity and accessory sinuses
818956004 – Benign sinonasal papilloma
Differential Diagnosis & Pitfalls
- Inflammatory polyp
- Inverted ductal papilloma – Originates from excretory duct of salivary glands, remaining confined to ductal lumen (circumscribed lesion).
- Nasal polyp with squamous metaplasia – Histology may show hyalinized basement membrane, salivary glands, and absence of transitional epithelium with inverted pattern.
- Synchronous or metachronous invasive carcinoma (squamous cell carcinoma, adenocarcinoma, verrucous carcinoma)
- Rhinosporidiosis – Histology shows organisms in the epithelial or stromal layer.
- Low-grade papillary adenocarcinoma – Histology shows nuclear pleomorphism, invasive growth, and mitotic activity with no oncocytic pseudostratified epithelium.
- Mucoepidermoid carcinoma
- Sinonasal undifferentiated carcinoma