Purpose: To elucidate the imaging features of subsequent metastases to the in-transit lymph nodes in the floor of the mouth of patients with squamous cell carcinoma (SCC) of the tongue.
Materials and methods: From 1997 through 2007, five tongue SCC patients with mass lesions in the floor of the mouth suggesting subsequent metastases to the in-transit lymph nodes were shown on imaging studies, and enrolled in this retrospective study. The lesions were demonstrated initially by conscientious monthly repeated follow-up sonography, followed by post-contrast CT or MRI. We named lymph node metastases observed posterior to the sublingual space and medial to the submandibular gland as the “parasubmandibular node” metastases, and considered the nodes belonging to the in-transit lymph nodes the same as the lateral lingual nodes locating in the sublingual space.
Results: With regard to the comparison between preoperative images and histopathological specimens obtained by radical neck dissection on a one-to-one basis, it was speculated that two cases had lateral lingual node metastases, two cases had parasubmandibular node metastases and one case had both. In the same research period, the total numbers of patients having in-transit lymph node metastases in the floor of the mouth were seven, which accounted for 16.3% of 43 tongue SCC patients with histopathologically verified metastases to the cervical lymph nodes.
Conclusions: We deemed that the parasubmandibular nodes played a role as in-transit lymph nodes locating on a lymph drainage pathway from the tongue to the internal jugular nodes, the same as the lateral lingual nodes. Accurate anatomical knowledge and careful observation is needed to detect the subsequent metastases to the lateral lingual and/or parasubmandibular nodes on imaging studies during a follow-up period after treatment of the tongue SCC with N0 neck.