Study of Epstein-Barr virus early RNA1 (EBER1) expression by in situ hybridization in thymic epithelial tumors of Chinese patients in Taiwan

Forty-one thymic epithelial tumors from Chinese patients in Taiwan, including 14 noninvasive thymomas, seven invasive thymomas, and 20 thymic carcinomas, were investigated for the presence of Epstein-Barr virus transcripts by in situ hybridization using digoxigenin-labeled riboprobes for EBER1 expression. None of the 14 noninvasive thymomas or seven invasive thymomas had detectable EBER1. Only one of 20 thymic carcinomas was positive for EBER1. This positive tumor was a lymphoepithelioma-like carcinoma found in a 19-year-old patient. Four different cases of lymphoepithelioma-like carcinoma were negative. Of note, the present case and all previously reported cases of Epstein-Barr virus-associated thymic carcinomas were lymphoepithelioma-like carcinomas. These results are consistent with those of several Western studies and do not support the view that there are geographic or racial differences affecting the role of Epstein-Barr virus in the pathogenesis of thymic epithelial tumors.