Background: The purpose of this study was to examine the frequency, pattern, and predictive factors associated with occult level II lymph node (LN) metastases in papillary thyroid carcinoma (PTC) patients with clinically metastatic lymph nodes in the lateral neck (level III, IV, and/or V) by preoperative ultrasonography.
Methods: We retrospectively reviewed the medical records of 52 PTC patients with clinically positive neck lymph nodes in level III, IV, and/or V based on preoperative ultrasonography, who underwent therapeutic lateral neck dissection (ND) (level II-V) between March 2004 and October 2009. All patients had no suspicion of clinically positive neck nodes in level II. Histopathological analysis of neck specimens according to each node level of the neck was performed, with special attention given to level II.
Results: Forty-two (81%), 41 (79%), and 6 (12%) patients had histologically positive lymph nodes in level III, IV, and V, respectively. Occult metastases in level II were observed in ten (19%) patients. Patients without suspicious positive LNs in both neck level III and IV by preoperative ultrasonography, and patients without pathologic LN metastases in level III, had no occult LN metastases occurrence to level II. Based on multivariate analysis, presence of more than four metastatic LNs was an independent predictive factor for occult level II metastases [P = 0.022, odds ratio (OR) = 7.738].
Conclusions: Prophylactic level II LN dissection may be omitted in PTC patients with clinically positive neck nodes if suspicious positive lymph nodes in level III are absent during preoperative ultrasonography.