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3.  MANAGEMENT OF CLINICALLY POSITIVE LYMPH NODES IN THE LATERAL NECK Recommendation:  In patients with clinically involved lateral compartment lymph nodes, a compartment-oriented, en bloc lymphadenectomy should be per- formed. A prophylactic lateral compartment neck dissection is not recommended. Type of Data:  Retrospective case series.   Grade of Recommendation:  Strong recommendation, moderate-quality evidence. Rationale Macroscopic lymph node involvement is not effectively treated with RAI therapy alone; therefore, surgical excision of metastatic lymph nodes provides the best option for regional control of disease. A compartment-oriented lymphadenectomy provides the most effective clearance of metastatic lymph nodes rather than removal of indi- vidually involved nodes (“berry picking”). In patients with PTC, metastases to the regional lymph nodes is common. Metas- tases are most common in the central compartment, followed by the ipsilateral lateral compartment. 94,95,121 Metastases to the contralateral lateral compartment or skip me- tastases (no clinical or pathologic evidence of central compartment metastasis with verified ipsilateral lateral compartment metastasis) can occur, but both are rare. 104–106 The presence of lateral compartment lymph node metastasis has been shown to confer a decrease in long-term survival in older patients with PTC. 64,122 Preoperative imaging of the lateral compartments is important because it can identify lymph nodes with abnormalities suggestive of metastasis. 65,66–69,71,73,74,94,95 Confirmation of metastasis by fine-needle aspiration (FNA) biopsy should be per- formed prior to lateral compartment lymph node dissection. Even if there is only one metastatic node identified preoperatively, additional microscopic metastases are often present; therefore, a compartment-oriented dissection of the involved compartment should be performed. 73,107,123–127 “Berry picking” lymph nodes in the lateral neck is discouraged, because it underestimates the extent of disease, may undertreat patients, and may make a future reoperative neck dissection more difficult. 33,127–133 Technical Aspects The lateral compartment comprises lymph node levels I, II, III, IV, and V, which are divided by anatomic landmarks and generally defined as follows (Fig. 2-8): ●● Level I (submandibular): Body of mandible superiorly, stylohyoid muscle pos- teriorly, and the anterior belly of the digastric muscle on the contralateral side anteriorly. ●● Level II (upper jugular): Upper third of the jugular vein, extending from the skull base to the inferior border of the hyoid. The spinal accessory nerve divides the group into IIA (anterior and inferior to the nerve) and IIB (superior and posterior to the nerve).