Epstein-Barr virus RNA detection and glandular differentiation in nasopharyngeal carcinoma: report of 2 cases.

Most tumors arising in the nasopharynx are either squamous cell carcinoma or so-called undifferentiated carcinoma of the nasopharyngeal type. Primary adenocarcinomas of the nasopharynx are rare, and glandular differentiation in undifferentiated carcinoma of the nasopharyngeal type has not been reported to date. We report 2 cases of undifferentiated carcinoma of the nasopharyngeal type that show distinct glandular differentiation by light microscopy, histochemistry, immunohistochemistry, and ultrastructure. Both tumors showed equal positivity for Epstein-Barr virus latent membrane protein and in situ hybridization for Epstein-Barr virus genome in the undifferentiated areas of the tumor and those featuring glandular differentiation.