Usefulness and limitations in ultrasonography for diagnosing neck lymph node metastases in patients with hypopharyngeal squamous cell carcinoma: comparison with pathological findings following neck dissection

We evaluated the usefulness and limitations in ultrasonography (US) for diagnosing neck lymph node metastases in patients with hypopharyngeal cancer by comparing the results of preoperative US examinations with postoperative pathological findings following neck dissection. Seventy-five previously untreated patients with hypopharyngeal squamous cell carcinoma underwent a curative procedure that included neck dissection. Preoperatively, all patients were examined by palpation, computed tomography (CT), and US. Postoperatively, all dissected neck lymph nodes were submitted for pathological examination. Results of pre-and postoperative examinations were then compared. US accuracy for each lymph node was 93.9%, while sensitivity was 78.0%, since hypopharyngeal cancer metastasizes early and easily to the neck lymph nodes, and it is difficult to detect small, pathologically positive nodes. Nine of 75 cases showed latent neck recurrence, and two of these were underestimated by US. The major cause for neck recurrence was considered to be the high rate of metastases in such cases, rather than a reduced dissection field. It is not rare to find very small, pathologically positive lymph nodes that US cannot detect in hypopharyngeal cancer. Efforts must therefore be expanded to improve the accuracy of US diagnosis. Care must also be taken when selecting cases for no or limited neck dissection.