Objectives To investigate the prevalence of sinonasal lymphoepithelial carcinoma (SNLEC) in Guangzhou, a high incidence area of nasopharyngeal carcinoma (NPC), and to detect whether it is associated with Epstein-Barr virus (EBV) infection.Methods Twenty confirmed SNLEC specimens were collected from all of the sinonasal carcinoma biopsies performed in the 8 years 1989-1996 at the Sun Yat-sen University of Medical Sciences. EBV encoded early RNAs were detected by use of in-situ hybridization. A variety of antigens, including the EBV nuclear antigen 1, latent membrane protein 1, BZLF1 protein, diffuse early antigen, viral capsid antigen and membrane antigen, were detected using immunohistochemistry. Additionally, 36 NPC specimens were used for comparison.Results Twenty SNLECs were identified. Seventeen SNLECs were developed in the nasal cavity, and 3 in the maxillary sinus. The mean age (46.25 y), male to female ratio (3∶1), histopathology and lymphoinfiltration of the 20 SNLECs were identical with those of the 36 NPCs. Thirteen (65.0%) of the 20 SNLECs showed an expansive growth pattern, while 27 (75.0%) of the 36 NPCs showed an infiltrating or mixed growth pattern. The majority of cancer cells in all of the 20 SNLECs showed EBV encoded early RNAs. The EBV nuclear antigen 1 expression of SNLEC was less intensive than that of NPC. The expression rate of latent membrane protein 1 for SNLEC (3/20,15%) was lower than that for NPC (19/36, 52.8%). The expression rates of BZLF1 protein (2/20, 10.0%), diffuse early antigen (19/20, 95.0%), viral capsid antigen (15/20, 75.0%), and membrane antigen (13/20, 65.0%) for SNLEC were higher than those (0/36, 0.0%; 31/36, 86.0%; 18/36, 50%; and 14/36, 38.9%) for NPC. Conclusions SNLEC is not uncommon in Guangzhou. This tumour is also consistently associated with EBV infection like NPC. As compared to NPC, the EBV harbored in SNLECs seems to express the EBV nuclear antigen 1 weakly and has a lower expression rate of latent membrane protein 1 as well as higher expression rat
