Ultrasonographic differentiation of benign from malignant neck lymphadenopathy in thyroid cancer

The aim of this study was to determine whether ultrasonography itself was able to distinguish benign from malignant lymphadenopathy in patients with thyroid cancer.

We evaluated lymph nodes in a group of patients with thyroid cancer. Nodes were detected and measured by ultrasonography, and their shape, echogenicity, size, and location were noted. Ultrasonographically guided fine-needle aspiration biopsy (FNAB) was performed, and smears were analyzed cytologically.

Ultrasonographically guided FNAB was performed in 578 neck nodes in a group of 631 patients with thyroid cancer. In most cases, metastases had a round shape and various echo structures, with a predomination of hypoechoic nodes without a hilum. There were statistical differences in size between metastatic and benign nodes in terms of maximum diameter, minimum diameter, and volume. Among these, minimum diameter and the shape of the nodes seemed to be the most reliable in suggesting malignancy. A round shape with a longitudinal/transverse ratio of less than 2 of hypoechoic nodes indicated the presence of metastases, and we then performed FNAB. The absence of an echogenic hilum and the presence of cystic portions and calcifications were significantly greater in malignancies than in benign lesions (P<.001). In most cases, metastatic nodules were situated in the lower third of the neck. Reactively enlarged nodes occurred more frequently in the upper part of the neck.

Ultrasonography itself cannot distinguish benign from malignant lesions, but an echographic appearance suggests malignancy and helps in the selection of the node to aspirate with ultrasonographically guided FNAB, which is crucial for a final diagnosis.