Occult lymph node metastases in neck level V in papillary thyroid carcinoma.

Background: The extent of lateral neck dissection for clinically evident nodal metastases in the lateral neck in a patient with papillary thyroid cancer (PTC) continues to remain controversial.

Methods: We reviewed retrospectively the medical records between March 2005 and March 2008 of 70 patients with PTC who underwent therapeutic lateral neck dissections (level II-V) to establish indications for omission of a level V lymphadenectomy. No patient in the study had a clinically positive level V lymph node. Neck dissection specimens were obtained for histologic analysis for node metastasis with respect to the individual neck levels.

Results: Thirty-four (49%), 52 (74%), and 48 (69%) patients had histologically positive lymph nodes in levels II, III, and IV, respectively. Occult metastases in level V were observed in 11 (16%) patients. Isolated positive level V lymph nodes were never found, while all patients with positive level V lymph nodes had simultaneous positive level IV lymph nodes. In addition, there was no instance of a pathologically positive lymph node in level V without a suspicious metastatic lymph node in level IV by preoperative ultrasonography. In multivariate analysis, simultaneous multilevel involvement (level II, III, and IV) of lymphatic metastases was associated with level V metastasis.

Conclusion: Level V lymphadenectomy may be omitted in the treatment of PTC patients if positive nodes are not found on histologic exam (frozen section analysis) or by ultrasonography in level IV.