EPSTEIN-BARR-VIRUS IS DETECTED IN UNDIFFERENTIATED NASOPHARYNGEAL CARCINOMA BUT NOT IN LYMPHOEPITHELIOMA-LIKE CARCINOMA OF THE URINARY-BLADDER

The Epstein-Barr virus (EBV) is associated with nasopharyngeal carcino ma (NPC) and with lymphoepithelioma-like carcinomas developing-in cert ain anatomic sites. In this study, an in situ hybridization was used t o identify EBV-encoded ribonucleic acid (RNA) (EBER1) transcripts in 3 2 of 45 cases of NPC but not in any of the 11 lymphoepithelioma-like c arcinomas developing in the urinary bladder. EBER1 was most commonly d etected in those NPCs having undifferentiated or nonkeratinizing squam ous histology rather than the keratinizing squamous cell subtype of NP C. The EBV-encoded latent membrane protein I (LMP1) was expressed foca lly in only seven of 21 EBER1-positive NPCs by an immunohistochemical technique. These findings imply that EBER1 hybridization is more sensi tive than LMP1 immunohistochemistry on paraffin sections in detecting carcinoma-associated virus. Previous in vitro studies have suggested t hat LMP1-expression might be a function of differentiation, but this s tudy-of naturally infected NPCs showed no strong correlation between L MP1 positivity and degree of tumor differentiation, albeit a limited s pectrum of differentiation that could be examined. In two cases in whi ch frozen tissue was available, the NPCs were monoclonal with respect to viral DNA structure, implying that the virus was present before mal ignant transformation. Unlike NPCs, the lymphoepithelioma-like carcino mas of the bladder were uniformly EBV negative, lending further eviden ce to the growing body of literature linking EBV with lymphoepithelial carcinomas of foregut-derived tissues but not with similar-appearing tumors developing in other anatomic sites. HUM PATHOL 26:1207-1214. Th is is a US government work. There are no restrictions on its use.