The management of intervening lymph nodes in the surgical treatment for oral cancer : Focus on the lingual lymph nodes in patients with tongue carcinoma.

Intervening lymph nodes appear inconstantly and interrupt the lymphatic collecting vessels. Intervening lymph nodes in the course of lymphatic vessels from the oral cavity to the cervical lymph nodes are the lingual and facial lymph nodes. In patients with oral cancer, metastases can occur in these nodes. In this article, we review the anatomical location, characteristics of metastasis, surgical consideration, and issues of these nodes in patients with tongue carcinoma. Lingual lymph nodes are classified into median and lateral lingual lymph nodes according to their anatomical location. The median lingual lymph nodes are situated in the lingual septum, and the lateral lingual lymph nodes are situated in four anatomical areas (sublingual space, submandibular space, medial surface of the hyoglossus muscle, and lower end of the parapharyngeal space) along the lingual artery, vein, and hypoglossal nerve. Previous studies have reported the incidence of median and lateral lingual lymph node metastasis to be 0.5–3.0％ and 1.4–14.3％, respectively. Although lingual lymph node metastases are uncommon, clinicians should be aware of them in all patients with tongue carcinoma, as the prognosis is poor when they do occur. Given the unfavorable prognosis associated with delayed metastases in lingual lymph nodes, it is recommended that these nodes be resected prior to the clinical appearance of metastases. However, the surgical procedure employed may vary depending on the location of these nodes. Resection of the lingual lymph nodes in the sublingual space (or part of it), the submandibular space, and the lower end of the parapharyngeal space can be performed during neck dissection. Further accumulation and analysis of cases are required to elucidate predictive factors for lingual lymph node metastasis and to develop diagnostic modalities and adjuvant therapies for lingual lymph node metastasis.