[Cervical lymph node metastasis in clinical N0 papillary thyroid carcinoma].

OBJECTIVE: To study the patterns of cervical lymph nodes metastasis and the surgical managements of cervical lymph nodes in clinical N0 (cN0) papillary thyroid carcinoma.

METHODS: Fifty-one consecutive patients with papillary carcinomas without clinical evidence of cervical lymph node involvement were included in the study between August 2007 and September 2010, in which 53 sides underwent neck lymph node dissection. Preoperative lymphoscintigraphy intra-operative hand-held gamma probe detecting and blue dye technique were used to detect the sentinel lymph node (SLN). SLNs were sent to frozen-section and the results were compared with specimen of routine selective neck dissection. All the pathologic specimens were reviewed by pathologists, counting the numbers of pathologic positive nodes and mapping the localization of positive nodes in level II, III, IV, V and VI respectively. The following criteria were used to study the predictive value of lateral neck compartment lymph node metastasis: age, multifocality of the tumor, extracapsular spread (ECS), tumor size, and the number of central compartment metastasis nodes. Univariate analysis with the χ2 test was used to analyze the statistical correlation between lateral neck compartment lymph node metastasis and the other clinical factors. Multiple logistic regression analysis was used to identify the multivariate correlates of lateral neck compartment metastasis.

RESULTS: The occult lymph node metastasis and lateral neck metastasis rates were 77.4% and 58.5% respectively, central compartment metastasis ≥3 nodes was the only independent predictive factor for the metastasis in lateral neck. Twelve sides were pN0 and other 41 sides were pN+ in all 53 side specimens. Of 41 sides with pN+, 17 sides (41.5%) involved single site and 24 sides (58.5%) involved multi-sites. The distribution of metastasis lymph nodes:level VI 62.3%, level III 52.8%, level IV 30.2%, level II 18.9%, and level V 0%.

CONCLUSIONS: Cervical occult lymph node metastasis in cN0 papillary thyroid carcinoma mainly localizes in level VI, level III, level IV and level II.Selective neck dissection including level VI, III, IV, II is enough for papillary carcinoma without clinical evidence of cervical lymph node involvement.