Interestingly, the benign lymph nodes in the superior jugular territories vary in appearance compared to the benign lymph nodes in the mid- and lower jugular territories. Left and right lymph nodes in the superior jugular territories should be compared on side-by-side images to assess symmetry. Asymmetry suggests metastatic involvement.

Imaging Features: Ultrasound. On initial US evaluation, the 1.3-cm right superior neck lymph node (Fig. 22.2a) was thought to potentially be metastatic with loss of central hilum. There was no vascular flow or calcification. US-guided biopsy was considered.

Comparison with the contralateral 1.4-cm left superior neck node (Fig. 22.2b) revealed a symmetrical appearance suggesting that the lymph nodes were either both benign or bilateral metastatic adenopathy .

US-guided FNA was considered based on concern for absent hilum and prominent rounded lymph nodes which may have been caused by bilateral metastasis.

Diagnosis: US–guided biopsy was performed on the right and left superior neck lymph nodes. The FNAs revealed benign nodes with no malignant cells. In this case, the symmetry of the superior neck nodes was within normal limits.

Ultrasound imaging of the soft tissues of the neck should include a two-on-one image of the right and left superior neck lymph nodes for comparison. Symmetry may assist in defining the benign appearance of the superior neck nodes in a specific patient.

Imaging Features: Right superior neck palpable 1.4-cm lymph node (Fig. 22.3a) created concern for an enlarged metastatic lymph node until comparison of 1.5-cm palpable left superior neck lymph node (Fig. 22.3b). The asymmetry suggests that the left superior neck lymph node is the metastatic node.

Diagnosis: US–guided FNA of the right and left superior neck lymph nodes revealed that the 1.4–cm right superior neck palpable lymph node was benign and the left 1.5–cm palpable lymph node was metastatic papillary carcinoma.

We have found that traditional criteria of size greater than 0.5 cm, shape of taller than wide, and irregular borders are not powerful indicators of malignancy. Although no single sonographic feature is pathognomonic for a metastatic lymph node, certain features should raise suspicion of a malignant lymph node. The combination of several features may be even more suggestive of metastatic adenopathy . These features include a full or rounded shape, disrupted or displaced hilum, disorganized vascularity, calcifications, cystic change, bulging of a component of the lymph node, and the presence of intranodal punctate regions of increased echogenicity. Of importance is that ultrasound characteristics are sensitive but not disease specific for a metastatic lymph node. Thus, US-guided FNA should be performed on lymph nodes of concern to establish the diagnosis.

Metastatic involvement of a lymph node may present as distortion of the normal echogenic central hilum.

Imaging Features: Abnormal right mid-neck lymph node with displaced hilum in the longitudinal (Fig. 22.4a) and transverse (Fig. 22.4b) planes.

Diagnosis: US–guided FNA (Fig. 22.4c ) revealed metastatic PTC.

The hilum may be absent in a metastatic lymph node due to infiltration of metastasis.

Imaging Features: Abnormal 0.5-cm left inferior neck lymph node (Fig. 22.5a) and 1.2-cm palpable left mid-neck lymph node (Fig. 22.5b) in the transverse planes with hilum absent in both lymph nodes.

Diagnosis: US–guided FNA revealed anaplastic transformation of PTC in the left and right jugular territories.

Vascular flow normally transverses the central echogenic hilum in a linear configuration. Metastatic infiltration of a lymph node may cause disorganization of the vascular flow.

Imaging Features: Abnormal 0.8-cm right inferior neck lymph node, in the longitudinal plane, with disorganized vascular flow (Fig. 22.6a) and a 2.5-cm right superior jugular territory lymph node in the longitudinal plane with normal central hilar vascular flow for comparison (Fig. 22.6b).

Diagnosis: US–guided FNA revealed papillary thyroid cancer.