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Whether chronic lymphocytic thyroiditis (CLT) influences the risk of development and the progression of papillary thyroid cancer (PTC) remains uncertain. We investigated the effects of CLT on the clinicopathologic features and prognosis of PTC. Two thousand nine hundred twenty-eight consecutive patients with PTC treated between 2009 and 2017 were divided into two groups: one with chronic lymphocytic thyroiditis and one without; 1174 (40%) of the patients had coincident CLT. In univariate analysis, CLT correlated positively with small tumor size, frequent extrathyroidal extension, multifocal diseases, and p53 but negatively with central lymph node (LN) metastasis and BRAF mutation. In multivariate analysis, CLT was associated with extrathyroidal extension and multifocal disease; however, it was not a prognostic factor for recurrence even though it was associated with two aggressive factors. Compared with patients with PTC alone, there were more retrieved central LNs in the PTC + CLT group, and these patients also underwent more invasive diagnostic tests such as fine needle aspiration cytology and frozen biopsy of LN. The CLT patients with PTC had better behavior features and prognoses than did those with PTC alone despite frequent multifocality and extrathyroidal extension. However, precaution may be necessary to avoid performing invasive diagnostic procedures for lateral LN metastasis and to manage the patients appropriately.

Prophylactic dissection facilitates identification of central lymph node (LN) metastasis in patients with papillary thyroid cancer (PTC). Because most staging systems do not stratify risks by the number of LN metastases, postoperative treatments vary among different institutions. Therefore we investigated the significance of number of LN metastases in risk stratification for recurrence in PTC.A retrospective review was performed for 3,305 patients who had undergone thyroidectomy at Ajou University Hospital. A total of 2,462 patients (73.5 %) underwent total thyroidectomy, and another 3,152 (94.1 %) underwent central LN dissection. Lateral cervical LN dissection had been performed in 420 patients (12.5 %).There were 115 patients with recurrence (3.4 %). Recurrence-free rates were 94.6 % at 5 years and 89.4 % at 10 years. On univariate analysis, prognostic factors for recurrence were extent of thyroidectomy, tumor size, capsular invasion, T stage, N stage, number of LN metastasis, TNM stage, and radioactive iodine (RAI) therapy. On multivariate analysis, number of LN metastasis and N stage were significant prognostic factors for recurrence. Recurrence-free rate was significantly different between patients with 0-1 LN and those with 2 or more LN.Number of metastatic LN was a significant prognostic factor, in addition to the N stage. Therefore, number of metastatic LN must be considered for postoperative staging system to tailor treatment and follow-up recommendations. In addition, patients with ≥2 metastatic LN may benefit from total thyroidectomy and RAI therapy with postoperative follow-up with serum thyroglobulin.

Papillary thyroid carcinoma (PTC) patients show a high rate of cervical lymphatic metastasis. However, there are no universal binding guidelines for the extent of lateral cervical lymph node dissection (LND) in such cases. In particular, the need for LND above the spinal accessory nerve (SAN) remains controversial. The present study examined whether level IIb lymph node (LN) dissection is always necessary in PTC patients with lateral cervical LN metastasis. The study prospectively examined 167 PTC patients with lateral cervical LN metastasis who underwent modified radical neck dissection (MRND) in our institution from November 2005 to March 2007. The MRND was bilateral in 24 cases. All patients underwent level II, III, IV, and V LND. Levels IIa and IIb LNs were individually dissected in all cases. All LND was performed using strict leveling criteria by a single operating team. The patterns of lymphatic metastasis and potential risk factors for level IIb LN involvement were evaluated. The most common site of metastasis was level III (80.6% of cases), followed by level IV (74.9%) and II (55.5%). The metastasis rates in level IIa and IIb were 55.5% and 6.8%, respectively; all level IIb LN metastasis was accompanied by level IIa metastasis (p = 0.001). In addition, level IIb LN metastasis was found to be associated with the aggressiveness of lymphatic metastasis (i.e., the total number of metastatic LNs) (p