Updated definition of level VI lymph node classification in the neck

This update will enable us to precisely address the involvement pattern of level VI and to standardize treatment procedures in order to refine their indications and eventually improve their results and avoid treatment morbidity.

The neck level classification is being used worldwide to describe the lymph nodes status of the neck. It provides standardized data to properly evaluate and then improve our protocols for the management of neck metastasis in an evidence-based medical manner. Although level VI treatment is challenging in cancer of the larynx, pharynx, trachea, esophagus, and thyroid, our knowledge about its involvement relies on few non-standardized data, due to the inadequate definition of this region.

We propose an updated radiological and surgical definition of level VI, with the introduction of two sublevels which fulfill surgical, radiotherapy, radiological, and pathological concerns.

Level VIa encompasses prelaryngeal, intercricothyroidal, pretracheal, and perithyroidal nodes. Level VIb encompasses inferior laryngeal nodes. Within the traditional limits of level VI, all lymph nodes lying between the inferior border of the hyoid bone and the inferior border of the cricoid cartilage belong to level VIa. Between the inferior border of the cricoid cartilage and the top of the suprasternal notch, lymph nodes lying in front of the posterior face of the thyroid gland belong to level VIa; those lying behind this boundary belong to level VIb. We also discuss the definition of the superior mediastinal lymph nodes, which should not be mistaken for level VI.