Tissue of lymphoepithelial tumor metastasis was transplanted subcutaneously to thymus-aplastic “nude” mice. After 75 days a pea-size tumor was developing which again was transplanted to further murine passages. During the second passage the tumor was growing faster and material was taken for light and electron microscopy. The results were compaired with the datas obtained from the primary nasopharyngeal carcinoma and metastasis. The tumor cells of the metastasis and of the xenograft showed all morphological criteria of a non-ceratinizing squamous epithelial carcinoma of undifferentiated type. The ultrastructural criteria of the human NPC-tumor cells were all present including cytoplasmic deposits of Corona viruses and Herpes virus-like particles within the nuclei and the cytoplasm.
Comparative morphology of lymphoepithelial carcinoma in primary tumor, metastasis, and xenograft