[Clinical analysis of level V occult metastasis of papillary thyroid carcinoma]

To analyze the occult level V lymph node (LN) metastases in papillary thyroid carcinoma (PTC) with clinical factors.

The clinical data of 203 PTC patients with clinical positive neck lymph nodes in level II, III and IV based on preoperative ultrasonography, who underwent therapeutic lateral neck dissection (level II-V) between January 2001 and June 2009 were retrospectively reviewed. There were 60 male and 143 female patients in the study. The median age at diagnosis was 42 years (ranging from 16 to 76 years). The 203 patients had undergone ipsilateral thyroidectomy and simultaneously neck dissections (II-VI). All patients had no suspicion of clinical positive neck nodes in level V. Univariate and Multivariate analysis were performed using the Pearson chi-square test and a binary logistic regression test, respectively.

The rate of metastatic at levels II, III and IV was 47.3%(96/203), 79.8%(162/203), 81.3% (165/203), respectively. The rate of occult metastatic at level V were observed in 14.3%(29/203). In univariate analysis, LN metastasis in level V was statistically significantly more frequent in patients with positive level IV LNs (χ(2) = 5.651, P = 0.017) and positive LNs throughout the lateral neck (level III+IV) (χ(2) = 10.936, P = 0.001). Multivariate analysis showed that positive LN involvement in all lateral neck (level III+IV) is an independent predictive factor of level V LN metastasis (P = 0.046, OR = 4.550).

In PTC patients without suspicious LNs in neck level IV by preoperative ultrasound, prophylactic level V LN dissection may be omitted.