Malignant Transformation in HPV-Negative Sinonasal Inverted Papilloma: A 14-Year Single-Center Review

Abstract

Sinonasal inverted papillomas (SNIPs) are rare benign tumors of the epithelial cells that have the potential to recur and undergo malignant transformation. Although human papillomavirus (HPV) infection is always considered the first event favoring development of SNIP, it is not established as an eventual connection between viral pathogen and malignant transformation. Our aim was to document malignant transformation in HPV-negative (HPV wide-spectrum, HPV 16, HPV 18) SNIPs. A total of 29 cases from the Department of Pathology at Icahn School of Medicine at Mount Sinai Hospital from January 1998 to January 2012 were retrospectively reviewed. There were 24 males and 5 females, and the median age of surgical diagnosis was 55 years. Tumor sites included maxillary sinus (9), frontal sinus (4), nasal cavity (12, including turbinates/polyp, septum), sphenoid (2), ethmoid (1), and palate (1); 4 were bilateral (10 = left, 11 = right). IPs ranged from 0.3 to 4.0 cm in overall dimensions. Rate of recurrence was very high (18/27); >10 SNIPs recurred over two times or more. Most of the patients were white (17/29), 1 was African American, and 3 of 29 were designated as other (ethnicity not known for 8). Smoking history was positive for only 3 patients, and 3 patients reported some sort of allergies to seafood, grass pollen, and antibiotics. On histology, 1 patient showed SNIP with mild dysplasia, 1 showed squamous cell carcinoma in situ (SCCIS), and 1 showed invasive SCC into the septal bone and cartilage, poorly differentiated, arising from SNIP (2.3 cm in size) with metastasis to local lymph node. In our compilation of HPV-negative SNIPs, 3 cases (10%) showed carcinomatous foci (dysplasia, carcinoma in situ to invasive carcinoma). Although multiple previous studies have detected an association of HPV with both recurrent and malignant transformation, SNIPs have been known to spontaneously convert into malignancy without any HPV coinfection.