Ultrasound diagnosis of lymph node metastasis in head and neck cancer

The role of ultrasonic (US) examination in the detection of cervical lymph node metastasis from head and neck cancer has been evaluated. The subjects were 57 patients with carcinoma of the oral cavity, maxillary sinus or oropharynx who underwent radical neck dissection. The preoperative US and postoperative histopathological findings were compared in 181 lymph nodes (LNs) of 5 mm or more in diameter. LNs were evaluated by US with reference to their size, shape, boundary and internal echoes. The histologically positive rate was higher for larger LNs on US scans: 96% (44/46) of LNs of 15 mm or more were positive. On the other hand, 95% (18/19) of the flat LNs were negative. The positive rate was higher for well delineated than poorly delineated LNs, but similar among the homogeneous, heterogeneous and reflective core patterns of internal echoes. No LNs were detected by US in six of the 57 patients, of which four were true negative and the other two false negative. In the two false negative patients, histopathological examination showed a total of four LNs with two showing extensive extranodal spread of tumour and fibrosis of the surrounding tissue due to previous radiotherapy. Whether LNs are metastatic or not is difficult to determine directly by US. However, the positive rate can be enhanced by evaluation of the size, shape and boundary of the LN. US is indispensable for diagnosing cervical lymph node metastasis in patients with malignant head and neck tumours.