A clinical study of ultrasonography for lymph node metastases in head and neck cancer

Abstract

Ultrasonography (US) is very useful in evaluating cervical lymph node swelling in head and neck cancers. We studied problems with US in evaluating lymph nodes. Cervical lymph nodes were removed by radical neck dissection or modified radical neck dissection from 79 patients with squamous cell carcinoma in the head and neck. We studied the correlation between preoperative US findings and the histopathological features. Preoperative lymph nodes were measured three-dimensionally. We diagnosed lymph nodes as metastases when they meet two criteria: One is the shortest diameter exceeding 7 mm in level I and II and 6 mm in level III, IV and V. The other is shortest to longest diameter ratio exceeding 0.5. A total of 2004 lymph nodes were removed by neck dissection, and 199 lymph nodes were diagnosed histopathologically as metastases. Of the 199 metastatic lymph nodes, 93 (46%) were diagnosed as metastases by preoperative US findings and 33 (17%) were false negative. Thirty-six cases were diagnosed preoperatively as N0 by US findings, but 15 of these were pN(+) histopathologically. In the 15 cases, 21 lymph nodes were metastases. Of the 21 metastatic lymph nodes, 10 nodes were not detected by US. Thirty-one cases were diagnosed preoperatively as N1 by US findings, but 20 of these were pN2b histopathologically. In the 20 cases, 66 lymph nodes were metastases. Of the 66 metastatic lymph nodes, 46 were not diagnosed as metastases. They often located distant level from the lymph node diagnosed correctly as a metastasis. US is very useful in evaluating cervical lymph node metastasis, but it has the limitations indicated above. If 1 metastatic lymph node is detected by US, there will be multiple metastatic lymph nodes and sometimes they are distant from the original level. Radical neck dissection should be done for positive lymph nodes detected by US findings. If a lymph node is not clearly a metastasis, fine-needle aspiration cytology (FNA) should be done, because it provides more accurate diagnosis for metastatic lymph nodes.