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Background: Compared with conventional papillary thyroid carcinoma (PTC), follicular variant of PTC (FV-PTC) shows less aggressive behavior and better prognosis. Nonetheless, regional lymph node (LN) metastasis was found in 22.8% of FV-PTC patients. Because LN metastasis is a proven predictor of recurrence in PTC, it is important to assess LN metastasis in FV-PTC patients., Methods: We retrospectively reviewed 134 FV-PTC patients who underwent thyroidectomy with neck dissection., Results: Central LN metastasis (CLNM) and lateral LN metastasis (LLNM) were found in 50 (37.3%) and 16 (11.9%) patients, respectively. In the multivariate analysis for CLNM, male sex (adjusted OR 4.735, p = 0.001), nonencapsulated form (adjusted OR 2.863, p = 0.022), and tumor size >1.0 cm (adjusted OR 3.157, p = 0.008) were independent predictors of high prevalence of CLNM in FV-PTC patients. In the multivariate analysis for LLNM, microscopic extrathyroidal extension (ETE) (adjusted OR 3.939, p = 0.041) and CLNM (adjusted OR 13.340, p = 0.001) were independent predictors of high prevalence of LLNM in FV-PTC patients., Conclusions: Meticulous perioperative evaluation and prophylactic central neck dissection may be beneficial for FV-PTC patients with male sex, nonencapsulated form, and tumor size >1.0 cm. Moreover, cautious perioperative evaluation of lateral neck LN may be mandatory for FV-PTC patients with microscopic ETE and CLNM.

Background: Although the incidence among patients with bilateral lateral lymph node metastasis (LLNM) in N1b papillary thyroid carcinoma (PTC) is reported to be as high as 40%, only a few reports have addressed the characteristics of contralateral LLNM. Therefore, this study aimed to investigate the characteristics of patients with contralateral LLNM in N1b PTC., Methods: This study retrospectively reviewed 834 patients with N1b PTC who underwent modified radical neck dissection between January 1997 and June 2015., Results: Of the 834 N1b PTC patients, unilateral LLNM was found in 728 patients (87.3%) and bilateral LLNM in 106 patients (12.7%). The independent predictors of contralateral LLNM in N1b PTC patients were male sex (adjusted odds ratio [OR], 1.647; p = 0.039), tumor larger than 4 cm (adjusted OR, 6.700; p < 0.001), multiplicity (adjusted OR, 1.754; p = 0.040), bilobar involvement (adjusted OR, 1.971; p = 0.010), and bilateral central LN metastasis (CLNM) (adjusted OR, 2.829; p = 0.025). Moreover, contralateral LLNM significantly increased the risk of overall (adjusted hazard ratio [HR], 1.943; p = 0.016) and lateral neck (adjusted HR, 2.246; p = 0.015) locoregional recurrence., Conclusions: In the preoperative period, the meticulous evaluation of contralateral lateral neck may be required for male N1b PTC patients with tumor larger than 4 cm, multiplicity, bilobar involvement, and/or bilateral CLNM. In the postoperative period, N1b PTC patients may be re-stratified according to the contralateral LLNM, and meticulous follow-up assessment is required for N1b PTC patients with contralateral LLNM.

Background: Because of the limitations in ultrasonography (US), the advantages of computed tomography (CT) for detecting central lymph node (LN) metastasis have been suggested in papillary thyroid carcinoma (PTC)., Methods: First, we compared the diagnostic accuracy of US and CT for detecting central LN metastasis in 6577 central neck levels from 3668 PTC patients. Second, to examine the clinical impact of CT-detected central LN metastasis (CT cN1a) in PTC patients with clinically node negative in US (US cN0), we selected two groups: group I comprised 1245 US cN0 PTC patients who did not have CT scans and did not undergo central neck dissection (CND), while group II comprised 348 US cN0 and CT cN1a PTC patients who underwent CND. After propensity score matching, 254 matched pairs were yielded., Results: For detecting central LN metastasis, CT showed significantly higher sensitivity (38.9 vs. 27.5 %; p < 0.001) and accuracy (66.1 vs. 63.2 %; p < 0.001) than US. Furthermore, US + CT showed significantly higher sensitivity (47.8 vs. 27.5 %; p < 0.001) and accuracy (69.0 vs. 63.2 %; p < 0.001) than US. After matching, radioactive iodine ablation (81.5 vs. 85.8 %; p = 0.235) and locoregional recurrence (p = 0.663) were not significantly different between groups I and II., Conclusions: Despite the diagnostic advantages of preoperative CT, 'CT-based CND' in US cN0 PTC patients did not significantly influence postoperative management and locoregional recurrence. The strategy for the management of central neck in PTC patients can be sufficiently determined by US only.

Background: Due to the low incidence of level 2b metastasis and the risk of spinal accessory nerve injury, previous studies have argued against routine level 2b dissection for N1b papillary thyroid carcinoma (PTC). However, other studies have suggested the importance of including level 2b during lateral neck dissection. Therefore, this study aimed to determine the necessity of routine level 2b dissection., Methods: The study retrospectively reviewed 327 N1b PTC patients who underwent unilateral modified radical neck dissection between January 1997 and May 2016., Results: The incidence of level 2b metastasis was 10.4 %, compared with 53.5 % for level 2a metastasis. The univariate analysis showed that large tumor size (p = 0.027) and simultaneous lateral lymph node metastasis (LLNM) (p = 0.002) were significantly associated with level 2b metastasis. The multivariate analysis showed that three-level (adjusted odds ratio [OR] 6.032; p = 0.020) and four-level (adjusted OR 9.398; p = 0.012) simultaneous LLNM were independent predictors for level 2b metastasis., Conclusions: Due to the low incidence of level 2b metastasis, routine level 2b dissection may not be necessary for N1b PTC patients. Level 2b dissection may be reserved for patients with more than three-level simultaneous LLNM or clinical/radiological evidence of level 2b metastasis.

Background: Because lymph node (LN) metastasis has been proven to be a predictor for locoregional recurrence (LRR) in papillary thyroid microcarcinoma (PTMC), better knowledge about the predictors for LN metastasis in PTMC is required., Methods: We retrospectively reviewed 5656 PTMC patients who underwent total thyroidectomy and central neck dissection and/or lateral neck dissection between January 1997 and June 2015., Results: Male gender (adjusted odds ratio [OR] 2.332), conventional variant (adjusted OR 4.266), tumor size >0.5 cm (adjusted OR 1.753), multiplicity (adjusted OR 1.168), bilaterality (adjusted OR 1.177), and extrathyroidal extension (ETE) (adjusted OR 1.448) were independent predictors for high prevalence of central LN metastasis (CLNM), whereas per 10-year age increment (adjusted OR 0.760) and chronic lymphocytic thyroiditis (adjusted OR 0.791) were independent predictors for low prevalence of CLNM. In addition, male gender (adjusted OR 1.489), tumor size >0.5 cm (adjusted OR 1.295), multiplicity (adjusted OR 1.801), ETE (adjusted OR 1.659), and CLNM (adjusted OR 4.359) were independent predictors for high prevalence of lateral LN metastasis (LLNM), whereas per 10-year age increment (adjusted OR 0.838) was an independent predictor for low prevalence of LLNM. There was a statistically significant difference in LRR with regard to nodal stage (p < 0.001)., Conclusions: Meticulous perioperative evaluation of LN metastasis is required for PTMC patients with the above predictors.