Answer: Inverted papilloma

Histology: Lesion has a typical morphologic appearance of inverted Schneiderian papilloma, in that it is composed of thickened, nonkeratinizing squamous or intermediate type epithelium which invaginates into the stroma. The epithelium lacks significant cytologically atypia and is associated with neutrophil clusters and microabscesses. The lesion erodes into bone, which is an accepted feature of inverted papilloma. These lesions are locally aggressive and this mandates medial maxillectomy in some cases.

Discussion: Squamous cell carcinoma would show greater cytologic atypia than inverted papilloma. Fungiform Papillomas are exophytic, and typically located on the nasal septum. Inflammatory polyps lack significant epithelial thickening, and typically have seromucinous glands within their stroma.

Approximately 10% of inverted Schneiderian papillomas are associated with squamous carcinoma, so these should be entirely submitted for histologic examination.