Level IIb lymph node metastasis in neck dissection for papillary thyroid carcinoma.

OBJECTIVE To determine the patterns of lateral cervical metastasis and the incidence of level IIb lymph node metastasis in papillary thyroid carcinoma. DESIGN Retrospective medical record review. SETTING Academic medicine. PATIENTS From March 1, 2000, to April 30, 2006, 46 consecutive patients (38 women and 8 men) with papillary thyroid carcinoma. INTERVENTIONS Patients underwent 55 modified radical neck dissections for the management of lateral cervical metastasis. MAIN OUTCOME MEASURES All patients had preoperative evidence of a metastatic cervical lymph node. All specimens were labeled and mapped by the operating surgeon to identify their levels. RESULTS Among 55 specimens, 82% (45 specimens) exhibited nodal disease at multiple levels. The incidences of metastases at level II, III, IV, and V nodes were 60% (33 specimens), 82% (45 specimens), 75% (41 specimens), and 20% (11 specimens), respectively. Skip metastases were present at a low rate (6% [3 specimens]). Among 12 specimens (22%) with metastatic lymph nodes at level IIb, 92% (11 specimens) had disease at level IIa. The rate of level IIb lymph node involvement in patients with metastatic lymph nodes at level IIa was 34% (11 of 32). CONCLUSIONS Tumor involvement at multiple nodal levels usually occurs when patients have lateral cervical lymph node metastasis. Neck dissection should include the level IIb lymph node whenever level IIa lymph node metastasis is found. Level IIb dissection is probably unnecessary when level IIa lymph nodes are uninvolved because the incidence of metastasis to level IIb is low if level IIa is not involved.