Immunohistochemical expression of epstein–Barr virus Latent Membrane Protein-1 in nasopharyngeal carcinoma

Background: Epstein–Barr virus (EBV) has a consistent global association with nasopharyngeal carcinoma (NPC). The detection of EBV in NPC has been shown to have diagnostic and prognostic importance. Latent membrane protein-1 (LMP-1) immunochemical staining is a well-recognized, rapid, and effective method of EBV detection. This study aims to determine the EBV status of NPC seen over 22 years, from 1992 to 2013 in Ahmadu Bello University Teaching Hospital (ABUTH). Materials and Methods: It was a retrospective study of all NPCs diagnosed at the Department of Pathology, ABUTH from January 1, 1992 to December 31, 2013. The paraffin-embedded tissue blocks of all histologically diagnosed NPCs within the study period were retrieved and examined. Cases in which the tissue blocks were missing, badly damaged, or had insufficient tissue were excluded from the study. Histopathological diagnosis was in accordance to the 2005 World Health Organization classification. EBV detection was done using immunohistochemistry (IHC) for EBV LMP-1. Data were analyzed using SPSS 24. Fisher's exact test statistic value is 0.545, which is not significant at P < 0.05. Results: A total of 112 NPC cases were histologically diagnosed, 66 (58.9%) of these were available for EBV LMP-1 IHC and 46 (41.1%) were excluded. EBV LMP-I IHC was positive in 51 samples (77.3%), while 15 (22.7%) were negative. There were 63 (95.5%) cases of nonkeratinizing carcinoma (NKC) seen, of which 49 (77.8%) were EBV positive and 14 (22.2%) were negative. Keratinizing squamous cell carcinoma (KSCC) constituted 3 (4.5%) cases, 2 of which were EBV positive (66.7%) and 1 was negative (33.3%). No basaloid squamous cell carcinoma case was available for the study. Conclusions: There is a high prevalence of EBV in NPC. However, there is no statistical difference in the prevalence of EBV in NKC and KSCC. NPC showed an association with EBV irrespective of histological type. LMP-1 IHC has proved useful in detecting EBV in NPC in this study.