| Cervical lymph node metastasis is one of the most important prognostic factors in patients with laryngeal carcinoma. The dissection areas of cervical lymph nodes largely depends on fully-understanding of the features of cervical lymph drainage of laryngeal carcinoma and correct evaluation of the cervical lymph node metastatic status; whereas occult cervical lymph node metastasis is a pivotal factor determining the survival and recurrence of cN0 stage laryngeal carcinoma. Pre- or intra-operative diagnosis of occult cervical lymph node metastasis can directly direct the selection of neck lymph node dissection method in cN0 stage laryngeal carcinoma. Consequently, in this study the sentinel lymph nodes (SLN) of cN0 stage laryngeal carcinoma were located to explore the prognostic value of sentinel lymph nodes on occult cervical node metastasis in cN0 stage laryngeal carcinoma and to discuss the mechanism of the lymph drainage of laryngeal carcinoma. The values and feasibility of intra-operative histology of frozen samples, series section HE staining, series section with fast immunochemical stain and nested RT-PCR in the assay of occult cervical node metastasis during operation were compared and analyzed. In the present study, location of the sentinel lymph nodes of 54 cases of cN0 stage laryngeal carcinoma was accomplished by intra-operative injection of blue dyes, of the 71 positive sentinel lymph nodes in the 52 cases were transversely split. Half of the positive lymph nodes were subjected for Ep-CAM nested RT-PCR, and the remaining were subjected for pathological study. Two sections were taken every 1.0 mm. The first section of each lymph node was used for frozen pathological examination, and others were used for series section with HE staining and with fast immunohistochemical staining, respectively. 10 cases were chosen as positive and negative control in series section with fast immunochemical staining and nested RT-PCR, respectively. All non-sentinel lymph nodes of these 52 cases were sent for nested RT-PCR to determine the sensitivity of RT-PCR. The final nested RT-PCR products of positive control were sent for sequence analysis. Results:1. In the 54 cases of laryngeal carcinoma, 72 positive sentinel lymph nodes in 52 cases of laryngeal carcinoma. The success rate was 96.3% (52/54). Sentinel lymph nodes in the assay of occult cervical node metastasis showed a prognostic value with sensitivity of 93.33%, accuracy rate of 98.08% and false negativity rate of 6.67%. This therefore indicates that location of sentinel lymph nodes of cN0 stage laryngeal carcinoma by injection of blue dye was possible and reliable. Examination of sentinel lymph nodes with highly sensitive methods can accurately reflect the status of cervical lymph node metastasis in laryngeal carcinoma. Our these methods provided the basis of selection of neck lymph node dissection method. 2. The distributions of the sentinel lymph nodes in supraglottic and glottic laryngeal carcinoma and the occult positive sentinel nodes in level II and III were not significantly different (P>0.05) whereas they are significantly higher than level VI. In this study, there were two cases (2 lymph nodes) of glottic laryngeal carcinoma whose sentinel lymph nodes were distributed in level VI (T3, T4, 1 case/lymph node) and 1 case of supraglottic laryngeal carcinoma whose sentinel lymph node was distributed in level VI (1ymph node). Distribution of sentinel lymph nodes was not found in level I, IV and V in all type of laryngeal carcinomas. This suggests that early regional lymph node metastasis in the patients with supraglottic and glottic laryngeal carcinoma occurs frequently in level II and III, however metastasis may be seen in level VI when extensive invation into the infra-glottic region. Similarly, on the basis of the results from this study, we believe that the infraglottic laryngeal carcinoma readily metastasize to level VI (and/or IV) in early stage, however metastasis to level II and III may occur once extensive invasion to the supragl...
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