![]() Distribution of nodal disease likely varies between primary presentation and recurrent disease. recently published a thyroid-specific, multidisciplinary, clinically validated nodal classification system that divides the neck into multiple stand-alone surgically distinct, side-specific compartments. In addition to the lymph node levels described above, many classification systems pertaining to the cervical lymph nodes have been published, including Union for International Cancer Control (UICC) classification, American Head and Neck Society (AHNS) classification, Japanese classification and the compartment classification (German classification). ![]() An exception to this is a patient with bulky lateral neck nodal disease where these areas may require dissection. Typically standard neck dissection for papillary carcinoma of the thyroid excludes Levels I, IIB, and V due to the low prevalence of disease in these subareas. A Level VII or superior mediastinal group has also been described which appears to be encompassed in the lower part of the central neck dissection group described by ATA. It extends from the hyoid bone superiorly to the clavicle. Level VI (central compartment) is composed of four subcompartments: (1) prelaryngeal (Delphian nodal group), (2) pretracheal, (3) left paratracheal, and (4) right paratracheal. It is subdivided into the region 5A above the level of the cricoid cartilage and 5B (supraclavicular region) below the level of the cricoid cartilage. Level V is a triangular region bounded anteriorly by the posterior edge of the sternocleidomastoid muscle (SCM) and posteriorly by the anterior edge of the trapezius muscle. Level IV (lower jugular region) extends from the cricoid cartilage down to the clavicle. Level III (mid-jugular region) extends from the hyoid superiorly to the cricoid cartilage inferiorly. Level II (upper jugular region) extends from the skull base and spinal accessory nerve superiorly to the hyoid bone inferiorly and is subdivided into IIA below the spinal accessory nerve and IIB above the spinal accessory nerve. For Levels II–IV, the posterior border is the posterior edge of the sternomastoid muscle, and the anterior border is the laryngeal complex. Level I constitutes lymph nodes above the anterior and posterior bellies of the digastric muscle cephalad to the hyoid bone and inferior to the inferior border of the mandible and includes the submental group of nodes. ![]()
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