Metastasis to the Lingual Lymph Node in Patients with Squamous Cell Carcinoma of the Floor of the Mouth:A Report of Two Cases

Cancer of the tongue or the floor of the mouth sometimes metastasizes to the lingual lymph node. We present two patients with squamous cell carcinoma of the floor of the mouth who developed metastases to the lateral lingual lymph nodes. Case 1, a 62-year old male, had squamous cell carcinoma of the floor of the mouth (T3N2cM0). He underwent tumor resection and bilateral neck dissection, and histological examination revealed five metastatic nodes including the lateral lingual node near the hyoid bone. No recurrent tumors were evident, but he died of pneumonia 10 months after the surgery. Case 2, a 62-year old male, had squamous cell carcinoma of the floor of the mouth (T2N2cM0). He underwent tumor resection and bilateral neck dissection, and histological examination revealed three metastatic nodes including the lateral lingual node near the sublingual gland. No recurrence was found in the oral and neck regions, but he died of liver metastasis 18 months after the surgery. Metastasis to the lingual lymph node may cause a recurrence of oral cancer in the neck, since conventional neck dissection cannot remove this node even in the case of en bloc resection of the primary tumor and the neck. When CT, MRI, or intra-operative palpation findings lead to a suspicion of metastasis to the lingual lymph node, the area of neck dissection should be extended to include this node. Squamous cell carcinoma of the oral cavity often metastasizes to the cervical lymph nodes, and the prognosis depends upon the control of the metastatic rather than the primary tumor 3) . Neck dissection, including functional, modified, and radical dissection, has been used for patients with oral cancer accompanied by lymph node metastasis, but in some cases it resulted in neck failure. It has been reported that tumor recurrence after neck dissection often occurs in patients with multiple positive nodes and extra-nodal invasion 2) . However, recurrence near the hyoid bone was observed in some of our patients with tongue cancer accompanied by a single metastatic node but no extra-nodal invasion. It is known that lymph nodes occasionally are located along some lymph vessels of the tongue and are known as lingual lymph nodes. The existence of lingual lymph nodes had