Sinonasal papillomas are tumors of the nasal cavity and paranasal sinuses. They are treated through complete resection under oncologic conditions. Two characteristics complicate follow-up: 1) frequent tumor recurrences (even many years after initial diagnosis), 2) possibility for malignant progression. This review elucidates risk factors for these two characteristics to depict “high-risk patients” for whom a closer follow-up is mandatory.
 Literature was searched in Pubmed (NCBI).
 The most important risk factor for recurrence is incomplete tumor resection. This comprises several more factors: inappropriate surgical procedure, large tumors, difficult surgical conditions due to tumor localization or to prior surgery. Young age and tobacco smoking are risk factors for frequent recurrences. In regard to malignant progression, extended tumors, smoking, senior age, female sex, bone invasion, and lack of inflammatory polyps have been identified as risk factors. Histopathological factors for both – recurrences and malignant progression – are epithelial dysplasia, hyperkeratosis, squamous hyperplasia, as well as (if known) increased proliferation, aneuploidy, and infection with human papillomaviruses.
 Complete resection of sinunasal papillomas under oncologic conditions is of utmost importance. A careful postoperative follow-up is mandatory. Most authors suggest at least a five-year, some a lifelong follow-up. Patients with one or more risk factors should be monitored more closely.

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