The Utility and the Limitations of Ultrasonography for Lymph Node Metastases.

Ultrasonography (US) is a very useful examination tool to evaluate cervical lymph node swelling in cases of head and neck cancer. Many reports have demonstrated that US is more reliable than palpation, CT or MRI for evaluating lymph nodes. Cervical lymph nodes removed by radical neck dissection from 19 cases with head and neck carcinomas were examined histopathologically, and observations were compared with preoperative US findings. Metastatic lymph nodes were diagnosed by size on US. Lymph nodes exceeding 7mm in Level 1 and 6mm in other cervical regions were diagnosed as metastases. A total of 457 lymph nodes were removed by radical neck dissection and 58 lymph nodes were positive for metastasis histopathologically. Twenty-nine of 58 lymph nodes were determined to be positive for metastases by preoperative US and they were all positive in histopathological examinations after operation. Since it is often difficult to detect the number of positive lymph nodes by US, there is a high possibility of multiple metastatic lymph nodes when one metastatic lymph node is detected by US findings. The prognosis of head and neck carcinomas is thought to depend on the number of metastatic lymph nodes, therefore, radical neck dissection should be performed in cases of positive lymph nodes detected by US findings.