[Analysis on occult micrometastasis in levels III - IV of cN0 neck in patients with oral tongue squamous cell carcinoma].

Objective: To investigate the frequency of micrometastasis in levels lII - IV of clinical negative neck (cN0) in patients with squamous cell carcinoma (SCC) of oral tongue, and to discuss the management of cervical lymph node for cN0 tongue SCC.

Methods: A total of 471 cervical lymph nodes derived from 25 patients with cN0 tongue SCC, including 263 lymph nodes in level III and 208 lymph nodes in level IV, were included in this study. All lymph nodes were re-examined by anti-cytokeratin (CK) immunohistochemical staining combined with semi-serial section per 500 microm.

Results: Among the 25 cases, seven patients were confirmed harboring metastasis in 11 lymph nodes of level III, and no positive lymph node in level IV was detected by routine hematoxylin-eosin (HE) staining. 11 positive lymph nodes in level IIl, which confirmed by HE staining, were also detected by immunohistochemical staining with CK combined with semiserial section. Among the 460 cervical lymph nodes in which HE staining did not show metastasis, only one lymph node in level III harboring a 2.0 mm x 1.5 mm micrometastasis was detected by immunohistochemical staining with CK, and no positive lymph node in level IV was detected by immunohistochemical staining with CK.

Conclusion: The frequency of occult metastasis in level IV was very low, so it seemed unnecessary to dissect level IV for all patients with cN0 tongue SCC.