| Research Abstract |
Majority of sinonasal lymphoma, which is one of the lethal midline granuloma, was recently categorized as sinonasal NK/T-cell lymphoma (NKTCL). They are more prevalent in Asia than Europe or North America and are associated with Epstein-Barr virus (EBV) infection.
Sixty-six cases with sinonasal NKTCL were collected from China (Beijing and Chengdu) and Japan (Osaka and Okinawa), and p53, K-ras, c-kit and β-catenin mutations were analyzed on paraffin-embedded specimens by PCR-SSCP followed by direct sequencing. Thirty-two of 66 cases (48.5%) had p53 mutations with 50 single-nucleotide substitution mutations. There were no significant differences in the incidence of p53 mutation among the cases in the 4 areas. However, the incidence in the cases in Osaka and Okinawa was two-third of those in Beijing and Chengdu. The results suggest the difference in the cause of nasal lymphomagenesis between the cases in Japan and China. There were no significant differences in the incidence of K-ras mutation among the cases in the four areas, but different spectrum were seen in different areas. In the c-kit, 12 of 16 cases (75.0%) in Beijing showed mutations, while only 5 of 22 Osaka cases (22.7%) and 5 of 23 Okinawa cases (21.7%) had mutations (p<0.05). The difference may be caused by some environmental confounding factors producing specific mutations. Furthermore, mutations occurred at highly restricted sites. Fourteen of 17 cases (82.4%) c-kit mutations in the exon 17 occurred at codon 825, and 3 of 9 mutations in exon 11 occurred at codon 559 and 561. In the β-catenin, 7 cases (10.6%) had mutations with eight single nucleotide substitutions. In Osaka, 4 of 22 cases (18.2%) had mutation, whereas no mutation was seen in Beijing cases.
Further studies on these genes mutations in China and Japan will be necessary to understand the difference in oncogenesis of sinonasal NKTCL.
|
