Central Cervical Nodal Metastasis from Papillary Thyroid Microcarcinoma: Pattern and Factors Predictive of Nodal Metastasis

Background  Although several factors are thought to predict the occurrence of lymph node metastases from papillary thyroid microcarcinoma (PTMC), the pattern of nodal metastasis has been rarely studied. We evaluated the pattern and factors predictive of central cervical metastasis from PTMC. Methods  Seventy-two patients with PTMC underwent total thyroidectomy and central neck dissection, including three who underwent therapeutic modified radical neck dissection. Lymph node involvement was analyzed by neck subsite, and clinicopathologic variables predictive of nodal metastasis were determined. Results  Central and lateral nodal metastases were found in 29 (40.3%) and 3 (4.2%) patients, respectively, and ipsilateral paratracheal, pretracheal, superior mediastinal, and contralateral paratracheal lymph node metastases in 27 (37.5%), 8 (11.1%), 4 (5.6%), and 1 (1.4%), respectively. Sex, age, tumor size, multifocality, bilaterality, extracapsular invasion, lymphovascular invasion, and MACIS (metastases, age, completeness of resection, invasion, size) for central node metastasis were not predictive of metastasis (P > .1). Temporary and permanent hypocalcemia was observed in 17 (23.6%) and 1 (1.4%) patients, respectively, and transient vocal fold paralysis in 1 (1.4%). Conclusion  Despite the absence of palpable neck nodes, PTMC is associated with a high rate of central lymph node metastasis to ipsilateral and pretracheal subsites. No clinicopathologic factor predicted nodal metastasis. In patients with PTMC involving one lobe and positive nodes, neck dissection may exclude the contralateral side.     

甲状腺乳头状癌颈部淋巴结转移规律及影响因素分析

目的探讨甲状腺乳头状癌（papillary thyroid carcinoma,PTC）颈部淋巴结的转移规律及其影响因素,为PTC颈部淋巴结清扫手术方式的选择提供依据。方法收集贵阳医学院附属医院甲状腺外科2009年1月至2011年12月期间收治的98例PTC患者的临床资料,对其淋巴结转移特点、规律及其影响因素进行回顾性分析。结果 98例患者中,共行颈部淋巴结清扫114侧。总颈淋巴结转移率为77.55%（76/98）,其中Ⅵ区淋巴结转移率为74.49%（73/98）,颈侧Ⅱ＋Ⅲ＋Ⅳ区为42.86%（42/98）,Ⅴ区为5.10%（5/98）。单因素分析结果显示：当肿瘤直径大于1 cm、侵犯甲状腺包膜、呈多灶性或年龄大于45岁时,Ⅵ区和Ⅱ＋Ⅲ＋Ⅳ区的淋巴结转移率较高（P〈0.05）。多因素分析结果显示：患者年龄、肿瘤直径、包膜侵犯及多灶性是颈部淋巴结转移的影响因素（P〈0.05）;包膜侵犯、多灶性、合并Ⅵ区淋巴结转移及合并颈侧Ⅱ＋Ⅲ＋Ⅳ区淋巴结转移是喉前淋巴结转移的影响因素（P〈0.05）;包膜侵犯和多灶性是跳跃性淋巴结转移的影响因素（P〈0.05）。结论 PTC易发生Ⅵ、Ⅲ及Ⅳ区淋巴结转移,应常规清扫Ⅵ区淋巴结。对颈部淋巴结转移规律的研究可为临床选择合理的颈部淋巴结清扫手术方式提供依据。     

乳头状甲状腺癌颈淋巴结转移方式及其相关影响因素的研究

目的评估乳头状甲状腺癌（PTC）颈淋巴结的转移方式及相关影响因素在颈部不同区域淋巴结转移中的意义。方法回顾性分析笔者所在医院甲状腺外科2008年12月至2011年12月3年期间行手术治疗的223例PTC患者的临床资料,就患者性别、年龄、术前TSH水平、肿瘤直径、是否为多灶、是否侵及甲状腺被膜及其周围组织、是否合并桥本甲状腺炎、是否合并结节性甲状腺肿以及肿瘤的T分期等因素与颈部不同区域的淋巴结转移之间的关系进行分析。结果单变量分析结果显示,年龄≥45岁及合并结节性甲状腺肿与中央区淋巴结转移有关（P〈0．05）,多发病灶与颈侧区淋巴结转移有关（P〈0．05）;多变量分析结果显示,年龄≥45岁及合并结节性甲状腺肿是中央区淋巴结转移的保护因素（P〈0．05）,多发病灶是颈侧区淋巴结转移的危险因素（P〈0．05）。Ⅱ-Ⅳ区是颈侧区淋巴结转移的常见区域,其中Ⅲ区转移率最高,达100％;当出现跳跃性转移时,Ⅱ-Ⅳ区是转移高发区域。结论对年龄〈45岁的PTC患者应常规进行中央区淋巴结清扫;如果患者同时合并结节性甲状腺肿,中央区淋巴结转移的风险会显著降低;当原发肿瘤为多发病灶时,应加强术中对Ⅱ-Ⅳ区淋巴结的探查,尤其是Ⅲ区淋巴结;当可疑跳跃性转移出现时,Ⅱ-Ⅳ区淋巴结应是常规清扫范围。     

选择性中央区淋巴结清扫治疗cNO甲状腺乳头状癌的临床价值

目的探讨选择性中央区淋巴结清扫术在临床颈淋巴结阴性（cN0）的甲状腺乳头状癌患者中的治疗价值。方法回顾性分析中国医科大学附属第一医院2007年1月至2011年12月期间收治的326例cN0甲状腺乳头状癌患者的临床资料,并对影响中央区淋巴结转移的相关因素进行分析。结果本组326例cN0甲状腺乳头状癌患者的中央区淋巴结转移率为35．89％（117／326）。年龄在〈45岁、肿瘤直径〉1cm及原发灶浸润包膜的cN0甲状腺乳头状癌患者的淋巴结转移率明显高于年龄≥45岁、肿瘤直径≤1cm及原发灶未浸润包膜的oN0甲状腺乳头状癌患者（年龄：46．56％比28．72％,P=0．001;肿瘤直径：44．44％比26．45％,P=0．001;包膜浸润：50．00％比33．09％,P=0．020）。进一步的多因素分析显示,年龄〈45岁和肿瘤直径〉1cm是cN0甲状腺乳头状癌中央区淋巴结转移的独立危险因素（P〈0。05）。术后6例出现暂时性喉返神经损伤,18例并发暂时性甲状旁腺功能低下,4例出现暂时性喉上神经损伤,1例并发急性喉头水肿,无永久性喉神经损伤、甲状旁腺功能低下等并发症发生。术后266例（81．60％）获得随访,随访7～67个月（平均31．2个月）,有3例发生侧颈区淋巴结转移。结论cN0甲状腺乳头状癌行选择性中央区淋巴结清扫术是必要的、安全的处理方式,建议对cN0甲状腺乳头状癌常规行患侧中央区淋巴结清扫术,特别是年龄〈45岁和肿瘤直径〉1cm的cN0甲状腺乳头状癌患者。     

cN0甲状腺乳头状癌行中央区颈淋巴结清扫术的临床研究

目的探讨中央区颈淋巴结清扫术对cN0甲状腺乳头状癌患者的意义。方法对解放军总医院2010年12月至2012年7月期间128例行中央区颈淋巴结清扫术的cN0甲状腺乳头状癌患者的临床资料进行回顾性分析。结果cN0甲状腺乳头状癌患者中央区颈淋巴结转移率为35．94％（46／128）。年龄〈45岁、原发病灶直径〉1cm、包膜或腺外侵犯的cN0甲状腺乳头状癌患者中央区颈淋巴结转移率均明显高于年龄≥45岁、原发病灶直径≤1cm、无包膜或腺外侵犯者（P〈0．05）。术后22例（17．19％）患者出现暂时性甲状旁腺功能低下,3例（2．34％）患者出现暂时性喉返神经损伤,无永久性喉返神经损伤及永久性甲状旁腺功能低下发生。术后随访14～32个月（平均23．4个月）,2例患者出现颈侧区淋巴结转移。结论中央区颈淋巴结清扫术对cN0甲状腺乳头状癌患者是一种必要、安全且有效的术式,且应由经验丰富的专科医生来实施。     

Axillary Lymph Node Metastasis from Papillary Thyroid Carcinoma: Report of a Case

We report a case of axillary lymph node metastasis (LNM) from papillary thyroid carcinoma (PTC) in a 21-year-old man. The patient presented with bilateral cervical and right axillary lymphadenopathy, and computed tomography (CT) showed a primary tumor of the thyroid and gross lymphadenopathy from the neck to the right axilla. We performed a total thyroidectomy with therapeutic nodal dissection. The resection of the primary thyroid tumor and all the node metastases was curative. Pathological examination confirmed that the resected lesions were PTC and nodal metastases from the primary tumor. Six years after the operation, cervical, upper mediastinal, and axillary lymph node recurrence developed and multiple lung metastases were found on a CT scan. He was treated with radioactive iodine therapy. Axillary LNM from PTC is unusual and seems to be associated with a poor prognosis. Thus, comprehensive treatment strategies are needed to improve the outcome of patients with PTC who present with axillary LNM.     

纳米碳在cNO期甲状腺乳头状癌中央区淋巴结清扫手术中的应用

目的研究纳米碳混悬液示踪技术在cN0期甲状腺乳头状癌中央区淋巴结清扫手术中的应用价值。方法将2012年5～10月期间在笔者所在医院科室治疗的68例cN0期甲状腺乳头状癌患者随机分为2组：未使用纳米碳淋巴示踪剂（对照组）32例,使用纳米碳淋巴示踪剂（示踪组）36例,均行甲状腺全切除术、患侧和（或）对侧中央区（Ⅵ区）淋巴结清扫术。比较2组患者的淋巴结清扫数、淋巴结转移情况以及手术相关指标（手术时间、术中出血量、术后引流时间和住院时间）。结果对照组和示踪组分别清扫中央区淋巴结205枚和324枚。其中,对照组手术清扫中央区淋巴结（6．41±1．56）枚／例,示踪组为（8．99±2．24）枚／例,多于对照组（P〈0．001）。对照组的中央区淋巴结转移率为40．6％（13／32）,与示踪组（47．2％,17／36）相比差异无统计学意义（P=0．762）,但示踪组喉返神经内侧区的淋巴结转移率（38．9％,14／36）高于对照组（12．5％,4／32）,P=0．029。2组患者的手术时间、术中出血量、术后引流时间、住院时间、术后切口出血发生率、一过性低血钙发生率及喉上神经损伤发生率比较差异均无统计学意义（P〉0．05）。2组患者术后均随访6个月,均无术后肿瘤复发、转移及死亡发生。结论纳米碳淋巴示踪技术可明显提高cN0期甲状腺乳头状癌患者中央区淋巴结的清扫数目,能比较准确地反映淋巴结的转移情况,从而对肿瘤进行准确的分期,以指导术后治疗,同时不增加（或延长）术中出血量、手术时间、术后住院时间及手术并发症发生率。     

Extent of Prophylactic Lymph Node Dissection in the Central Neck Area of the Patients with Papillary Thyroid Carcinoma: Comparison of Limited Versus Comprehensive Lymph Node Dissection in a 2-Year Safety Study

Background  To compare the “comprehensive” (including bilateral paratracheal, pretracheal, prelaryngeal lymph nodes) (CCND) with “limited” (saving contralateral paratracheal lymph nodes) central node dissection (LCND) for postoperative complications and disease recurrence rate in sonographically node-negative papillary thyroid carcinomas. Materials and Methods  From 2003 to 2005, 114 consecutive patients, diagnosed as sonographically node-negative thyroid papillary carcinomas, were included retrospectively. Among them, the LCND was performed in 56 patients and CCND in 58 patients, in combination with total thyroidectomy, based on the operator-dependent decision. We compared the complication rates and the recurrence rates between these two groups with a mean follow-up duration of 2 years. Results  Transient hypocalcemia was more frequent in the CCND group than in the LCND group (48.3% vs 26.8%, P = .02, odds ratio [OR] = 2.55). However, the other complication rates were similar in the two groups. In addition, the immediate postoperative reduction of parathyroid hormone (PTH) was more evident in the CCND group. The postoperative PTH levels increased up to a similar level (12.4 vs 11.8 pg/mL) over 6 months. The incidence of permanent hypocalcemia did not differ significantly between the two groups. Four (7.1%) and five recurrences (8.6%) were found in two groups, respectively, implying similar oncological safety during the 2-year follow-up. Conclusion  The LCND with total thyroidectomy could be an alternative treatment option for node-negative papillary thyroid carcinomas, because LCND had fewer short-term hypocalcemia and similar oncological outcomes during the 2-year follow-up. Further study enrolling a large number of patients with long-term follow-up is needed.     

Chyle Leakage in Patients Undergoing Thyroidectomy Plus Central Neck Dissection for Differentiated Papillary Thyroid Carcinoma

Background  Chyle leakage is an uncommon complication of lateral neck dissection for metastatic papillary thyroid carcinoma (PTC). There have been no reports on chyle leakage after central neck dissection not combined with lateral neck dissection. We therefore investigated chyle leakage in PTC patients undergoing thyroidectomy and central neck dissection. Methods  A total of 283 new patients with differentiated PTC underwent total thyroidectomy plus central neck dissection. The amount and duration of drain leakage, and the concentrations of triglycerides and cholesterol in drain fluid and serum were measured in patients who had suspected postoperative chyle leakage. The incidence and management of chyle leakage were analyzed. Results  Intraoperative chyle leakage was not found in any patient, although postoperative leakage was detected in four patients (1.4%). Mean ± standard deviation peak 24-hour drainage was 122 ± 57 mL, and duration of leakage was 10 ± 7 days. Mean triglyceride concentration of drainage fluid was 433 ± 182 mg/dL. These patients were treated with pressure dressings and a medium-chain triglyceride diet. One patient underwent intralesional injection of OK-432 for localized chyle accumulation. All chyle leakages stopped after conservative management without surgical intervention. Conclusion  Chyle leakage can occur after thyroidectomy and central neck dissection not combined with lateral neck dissection. These findings will aid in the recognition and treatment of this uncommon complication during the early postoperative period.     

Patterns of Lymph Node Metastases in Papillary Thyroid Carcinoma: Results from Consecutive Bilateral Cervical Lymph Node Dissection

Background  

In patients with papillary thyroid carcinoma (PTC), the appropriate extent of lymph node dissection has not yet been established due to lack of accurate patterns of lymph node metastases (LNM). The aim of this study was to clarify the LNM pattern in PTC patients based on our institution’s experience with a consistent technique of bilateral neck dissection, and to consider the rational extent of lymph node dissection.     

Lymph Node Status Influences Follow-Up Thyroglobulin Levels in Papillary Thyroid Cancer

Background  Elevated thyroglobulin (Tg) levels post surgery are associated with disease recurrence in papillary thyroid carcinoma (PTC). The aim of this study is to determine which clinicopathological factors influence Tg elevation following surgery and radio-iodine ablation (RAI) for PTC. Methods  A retrospective study of consecutive patients undergoing total thyroidectomy and RAI for PTC was carried out. Prophylactic central neck dissection (CND) was performed if the diagnosis of PTC was made preoperatively. Lateral neck dissection (LND) was guided by ultrasound findings. RAI was administered 6 weeks postoperatively. Stimulated Tg levels were measured at 12 months. Results  One hundred patients with PTC were studied. Forty patients had routine CND. The median tumour size was 15 mm. Median stimulated Tg level at 12 months was 0.3 μg/L. On multivariate analysis the number of metastatic lymph nodes removed had a significant positive association with serum Tg levels (P = 0.003). The total number of lymph nodes resected had a significant inverse relationship with serum Tg levels (P = 0.04). Tumour size, multifocality, vascular and capsular invasion did not appear to have significant correlation with Tg levels. Conclusion  Lymph node metastases are associated with increased postablative Tg levels in PTC. More complete lymphadenectomy is associated with lowering of Tg levels.     

多保留功能性颈淋巴结清扫在甲状腺乳头状癌手术中的应用

目的探讨多保留功能性颈淋巴结清扫术在甲状腺乳头状癌手术中的应用价值。方法回顾性分析21例甲状腺乳头状癌手术中行多保留功能性颈淋巴结清扫术患者的临床资料。结果21例共清扫淋巴结485枚,颈淋巴结转移率66．0％（320／485）;声音嘶哑2例;术后颈丛功能满意,颈部肌肉无僵硬萎缩,无肩下垂、抬肩无力及肩部疼痛,亦无耳后、肩部感觉障碍和面部水肿。均获随访,平均4（1～7）年;颈部复发1例,肺转移、全身多发转移各1例,无死亡病例。结论多保留功能性颈淋巴结清扫术在甲状腺乳头状癌手术中作用确切,在彻底清扫颈淋巴结的同时能更好地保留患者颈部功能及外形,避免术后颈面部水肿及感觉异常。但对于颈部淋巴结广泛转移且淋巴结较大,肿瘤外侵明显的不在该手术考虑范嗣内。     

Papillary Thyroid Carcinoma: Factors Influencing Recurrence and Survival

Background The prognosis of patients with papillary thyroid carcinoma (PTC) is usually favorable; however, a subset of patients can develop local recurrence or distant metastases. The aim of this study was to evaluate the prognostic factors influencing the recurrence and the survival rate in 950 PTC patients. Materials and Methods From 1990 to 2005, 950 consecutive patients affected by PTC were operated on at our Department. We analyzed the prognostic role of the following parameters: gender, age at initial treatment, extent of thyroid surgery, node dissection, tumor size, node metastases, distant metastases, stage, and 131-I therapy. Results Seventy-nine patients (8.3%) developed locoregional or distant metastases after an average follow-up of 7.8 years (range 2–17 years); in particular local recurrence was observed in 25 cases and distant metastases in 54 cases. The global 10- and 15-year survival rates were 91.38% and 88.69%, respectively. At univariate analysis, all variables were significantly correlated with recurrence (P = .001) except gender (P = .3); moreover, gender (P = .2), node dissection (P = .5), and node metastases (P = .06) were not significant on 10- and 15-year survival. At multivariate analysis the age at first treatment, T4, M+, stage IV, the extent of thyroid surgery, and the 131-I therapy resulted to be significant and independent prognostic factors (P < .001). Conclusion Our data, in disagreement with other staging systems, suggest that gender does not play a significant role both in recurrence and survival. Moreover, the 131-I therapy was a statistically significant prognostic factor at univariate and multivariate analyses.     

Prospective Identification of Chyle Leakage in Patients Undergoing Lateral Neck Dissection for Metastatic Thyroid Cancer

Background Lateral neck dissection for metastatic thyroid cancer includes the lower jugular nodes, but there has been little study of chyle leakage. We therefore prospectively examined chyle leakage that occurred during and after lateral neck dissection in treatment of thyroid cancer. Methods A total of 82 consecutive patients underwent 96 lateral neck dissections for metastatic differentiated thyroid cancer—42 in the right neck, 26 in the left neck, and 14 in both. All patients were monitored for intraoperative and postoperative chyle leakage. All postoperative drainage fluid and serum were chemically analyzed for triglycerides and cholesterol for early identification of chyle leakage. Results Intraoperative chyle leakage was observed during 5 of the 96 neck dissections (5.2%), all on the left side and all controlled by suturing chyle fistula, thus avoiding postoperative leakage. Postoperative chyle leakage was observed in 8 of the 96 neck dissections (8.3%), 5 in the right and 3 in the left neck. The mean peak triglyceride concentration of drainage fluid was significantly higher in patients with chyle leakage than in those without (309 vs 42 mg/dl, P < 0.001). To stop leakage, 2 patients underwent reoperations. Chyle leakage stopped within 5–62 days (mean 18 days) after surgery. Conclusions Chyle leakage related to lateral neck dissection for thyroid cancer is uncommon but may occur more frequently than reported previously, even in the right neck. Our findings may guide thyroid surgeons in both careful neck dissection in at-risk areas and proper postoperative management.     

Prognosis After Reoperation for Local Recurrence of Papillary Thyroid Carcinoma

Purpose To investigate the factors associated with a favorable prognosis after reoperation for local recurrent papillary thyroid carcinoma (PTC), we reviewed 45 patients who underwent surgery for first local recurrence of PTC.Methods We divided the patients into two groups. Group A (n = 28) had no second recurrence, and group B (n = 17) had second local recurrence after surgery for recurrence.Results The mean follow-up period after reoperation was 56.9 months. The mean age at the time of reoperation in group A was significantly lower than that in group B, at 48.1 years versus 62.3 years, respectively (P = 0.0007). The mean age at the time of the initial operation in group A was also significantly lower than that in group B, at 40.1 years versus 55.1 years, respectively (P = 0.0006). Patients with recurrent tumors only outside the area dissected at the initial operation (n = 27) had a better outcome than those with recurrence within the dissected area (n = 18; P = 0.0127). Patients who underwent systematic partial or modified neck dissection (n = 36) had a better outcome than those who underwent only simple local resection (n = 9; P = 0.0169).Conclusion For local recurrent PTC, systematic neck dissection is recommended over local resection of recurrent tumors.     

Case Report: Metastases from Thyroid and Nasopharyngeal Carcinomas in the Same Lymph Node Following Chemotherapy for Mantle Cell Lymphoma

We report a case of metastatic papillary thyroid carcinoma and undifferentiated nonkeratinizing nasopharyngeal carcinoma to the same cervical lymph node following chemotherapy for mantle cell lymphoma. Total thyroidectomy, right cervical nodal dissection, radioactive iodine-131 therapy and radiotherapy to the nasopharynx and the neck resulted in remission of both tumors. No recurrence was noted in follow-up for 48 months.     

Tumor-to-Tumor Metastasis: Renal Cell Carcinoma Metastatic to Papillary Carcinoma of Thyroid—Report of a Case and Review of the Literature

Metastatic disease to thyroid gland is a rare event. Although renal cell carcinoma (RCC) has been reported to metastasize the thyroid gland, metastatic RCC to a thyroid neoplasm is very unusual. We report a case of a 68-year-old man with history of RCC who presented with a 2.5-cm thyroid nodule. Histologic examination demonstrates a renal cell carcinoma metastatic to a papillary carcinoma of the thyroid. The clinicopathologic features of metastatic disease into a thyroid gland neoplasm are shown, and a review of the literature is presented.     

腔镜辅助技术在T1期甲状腺乳头状癌手术中的应用

目的探讨腔镜辅助技术在T．期甲状腺乳头状癌（papillary thyroid carcinoma，PTC）中央区淋巴结清扫术中的可行性。方法回顾性分析2013年1—7月我科收治并经术中冰冻切片和术后石蜡切片确诊PTC53例的临床资料，病灶最大径≤2．0cm，全麻下行单侧腺叶加峡部切除加同侧中央区淋巴结清扫术。根据病人意愿分为常规手术组（n=34）和腔镜辅助组（n=19），比较2组手术时间、出血量、清除淋巴结数目和喉返神经损伤发生率。结果手术均获成功，与常规手术组相比，腔镜辅助组切口短[中位数2．5cm（2．0～3．0cm）VS．4．6cm（3．8～5．0cm），Z=-6．039，P=0．000]，但手术时间长[（76．6±29．0）minV8．（59．7±18．3）min，t=2．609，P=0．012]。2组清除淋巴结数、出血量和声音嘶哑发生率差异无显著性（P〉0．05）。结论应用腔镜辅助技术治疗T1期甲状腺乳头状癌的效果与常规手术相似，尽管手术时间稍长，但其小切口更易于为年轻患者选择。     

Prognostic Factors in Papillary and Follicular Thyroid Carcinoma: Their Implications for Cancer Staging

Background Papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC) are two distinct histological types of thyroid carcinoma but have often been studied and staged as a collective group, known as differentiated thyroid carcinoma (DTC). However, this may not be an optimal approach to cancer staging. Methods A total of 760 patients with DTC, comprising 589 (77.5%) with PTC and 171 with (22.5%) FTC, being managed at our institution from 1961 to 2001 were retrospectively reviewed. Their clinicopathological features, treatment modalities received, and postoperative outcome were analyzed. Both univariate and multivariate analyses were performed to identify prognostic factors related to cancer-specific survival (CSS) for PTC and FTC. Results There were statistically significant differences between PTC and FTC in terms of age ≥50 years at diagnosis (P = .040), tumor size (P < .001), lymph node metastases (P < .001), distant metastases (P < .001), extrathyroidal extension (P < .001), multifocality (P = .002), capsular invasion (P < .001), extent of thyroid resection (P < .001), radioiodine ablation (P < .001), and external-beam irradiation (P = .003). Although PTC and FTC had similar 10-year and 15-year CSS (P = .846), each possessed its own set of independent prognostic factors for CSS. Age at diagnosis and completeness of resection were independent prognostic factors in both PTC and FTC. Conclusions There were marked differences in clinicopathologic features, treatment, and prognostic factors between the two histologic types of DTC. Different staging systems should be evaluated and validated for PTC and FTC individually in the future.