Ultrasound of Neck Lymph Nodes

Abstract

Lymph nodes in the neck have been historically divided into seven levels based upon surgical anatomy. The main problem with the ultrasound assessment of regional metastases of thyroid malignancies is the large number of diseases that are accompanied by lymph node enlargement and thus the difficulties involved in the differential diagnosis of the origin of the enlargement. Enlargement of a lymph node of the neck may appear as a manifestation of a variety of diseases, such as specific or nonspecific inflammation of head and neck organs, metastases, and hemoblastoses. The principle ultrasound signs of lymph node differentiation are the size, shape, structure, and vascularization. A normal lymph node has a width of up to 10 mm on transverse scan. Two main components of the lymph node—the cortex and medulla—are usually well differentiated. Vessels, if any are detected, are usually located within the hilum in normal or reactive lymph nodes. Even in large benign hyperplastic lymph nodes, the vascular pattern remains regular. US features that are suspicious for a malignant process in neck lymph nodes are listed in the chapter. The site of the metastasis does not directly correspond to the location of the primary tumor.