Epstein-Barr virus DNA, intermediate filaments and epithelial membrane antigen in nasopharyngeal carcinoma

The aim of this study was to investigate the expression of intermediate filaments (cytokeratin, vimentin), epithelial membrane antigen (EMA) and the presence of Epstein-Barr virus (EBV) DNA in undifferentiated nasophalyngeal carcinoma (NPC). A high incidence of nuclear signals in NPC was Sound in primaries and regional lymph node metastases (70%), using S-35-labelled probes of EBV plasmids for in-situ hybridization. Keratinizing squamous cell carcinomas were EBV-negative. All carcinomas were immune-reactive for cytokeratin (KL-1). 45% of the carcinomas were positive for vimentin. The expression of epithelial membrane antigen was restricted to epithelial cells and reduced in NPC as compared to the distribution pattern of cytokeratin. Both EBV DNA and vimentin in NPC were present in 9 cases. However, in 5 cases NPG were harboring EBV but were not immunoreactive for anti-vimentin antibodies. In no case was a vimentin-positive NPC also EBV-negative. The identification of cytokeratin subtypes revealed no specific cytokeratin pattern in NPC. The expression of vimentin in NPC is not specific for EBV, but seems to reflect the loss of intel-epithelial contact in anaplastic carcinomas.