Low Epstein-Barr virus count in sinonasal inverted papilloma.

Sinonasal inverted papilloma (SIP) is a benign tumour originating from the sinonasal mucosa showing an extensive growth pattern, a high risk of recurrence and a 5-10% risk to malignify. Epstein-Barr virus (EBV) is an oncogenic herpesvirus which infects most individuals the saliva eliciting a latent infection. Previous studies have been reporting variable data on EBV in SIP, and there is no present appreciation regarding the association between these. The aims were to investigate the presence and count of EBV in SIP and map the viral distribution in the epithelium versus the connective tissue. Fifty-three SIP patients were identified in the Pathology Department register at the University Hospital of Umeå. The biopsies were analysed with Epstein-Barr Encoded Region (EBER) hybridization. EBER-positive cells were counted in the epithelium and connective tissue. We found EBER-stained cells in 30% of the cases, where 19% of these had an abundance of stained cells, and the rest showed a low count. These findings demonstrate a low EBV count in SIP. EBV is less likely to be a causative agent in the formation of SIP, or its malignant transformation.