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.