No significant role of Epstein-Barr virus in the tumorigenesis of Warthin tumor.

To determine the significance of Epstein-Barr virus (EBV) in the tumorigenesis of Warthin tumor, formaldehyde-fixed and paraffin-embedded specimens of 21 tumors from 18 patients were examined by polymerase chain reaction (PCR)-Southern hybridization, in situ hybridization (ISH), and immunohistochemistry. PCR-Southern hybridization revealed the presence of EBV DNA in 13 of the 21 tumors (61.9%). However, ISH for EBV RNA showed that nuclei of the neoplastic epithelial cells of all tumors were negative. Although ISH for EBV DNA revealed that the nuclei of the neoplastic epithelial cells were positive in 4 of the 21 tumors (19.0%), the positive cells were sparsely distributed and there was no evidence of monoclonal proliferation of EBV positive neoplastic epithelial cells. Moreover, immunohistochemical reactions with antibodies against latent membrane protein 1 (LMP1) and EBV nuclear antigen 2 (EBNA2), were negative in all cases. Judging from these findings, we conclude that EBV does not play a major role in the tumorigenesis of Warthin tumor.