The papillomas of the sinonasal tract. A comprehensive review.

Papillomas are uncommon tumors of the sinonasal tract histologically derived from the Schneiderian membrane. Three distinctive variants are described, the exophytic, the inverting and the oncocytic types. On physical examination, their appearance varies from exophytic-fungiform seen in the exophytic variant, to polypoid-papillary in both the inverting and oncocytic variant. The presence of an asymptomatic mass or epistaxis and unilateral nasal obstruction are the typical presenting symptoms. Clinically they tend to recur and, although benign, they may erode the bone laminas by pressure, especially the inverting type, causing proptosis and other co-morbidities. Malignant transformation is seen both synchronously, on a pre-existing papilloma, and metachronously after several recurrences of papilloma. Schneiderian papillomas are at a date a topic of controversy regarding their etiology, pathogenesis and biological behavior. Furthermore, histologic criteria to assess dysplasia and malignant transformation are ill-defined. The present study aims to comparatively review the histologic types of papillomas, their etiology, the currently available criteria for malignant transformation, their treatment and prognosis.