Cytogenetic observations on the malignant epithelial cells and infiltrating lymphocytes of nasopharyngeal carcinoma.

Because of the presence of a No 14 chromosome marker abnormality in EB virus-carrying cells from African Burkitt's lymphoma (BL) but not from other origins, and the association of EB virus with nasopharyngeal carcinoma (NPC) as well as BL, both the malignant epithelial cells and the non-malignant lymphoid cells of NPC have been investigated cytogenetically. Chromosome spreads from seven NPC-derived lymphoblastoid lines were examined after banding; five lines were diploid and two were tetraploid. No consistent no. 14 chromosome abnormalities were found. Apart from a secondary constriction near the centromere of both no. 1 chromosomes in all cells of one diploid line, no consistent significant abnormalities were seen. Five NPC tumours, freed of infiltrating lymphoid cells by passage through nude mice, were similarly examined after spindle arrest in vivo. Two tumours were near-diploid, and three were hypo-tetraploid. Near-diploid cells had only minor chromosomal changes, but the hypotetraploid spreads from all tumours showed gross changes of uncertain origin, including frequent, major translocations. No. 14 chromosome marker changes were not seen, and there was no other consistent pattern of abnormality in tumour cells.