Nasopharyngeal carcinoma (NPC) belongs to the most common malignant tumours in certain parts of the world, e.g. South-East Asia. The undifferentiated type of NPC is associated with genomic Epstein-Barr virus (EBV) DNA. In normal epithelia of the nasopharynx cytokeratins (CK) 4, 5, 6, 13, 14, 15 and 19 are expressed. The aim of this study was to analyse the expression pattern of cytokeratins in NPC in the presence of EBV infection. Twenty primary or metastatic tumours from 13 patients suffering from a NPC were evaluated (formalin-fixed, paraffin-embedded). (35)S-labelled probes were used to detect EBV DNA in the tissue sections. Fourteen specimens (70%) were EBV positive. All positive specimens were undifferentiated NPC. All NPC were identified with broad-spectrum anti-CK antibody. Using a panel of anti-CK antibodies, there was no specific CK-expression pattern in NPC. In summary, undifferentiated NPC are strongly associated with EBV. The cytoskeleton of undifferentiated NPC reveals no specific pattern of CK expression.
