1 Department of Radiology and Center for Imaging Science, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine , Seoul, Korea.
2 Department of Pathology, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine , Seoul, Korea.
Thyroid. 2017 Sep;27(9):1177-1184. doi: 10.1089/thy.2016.0677. Epub 2017 Aug 7.
Follicular variant of papillary thyroid carcinoma (FVPTC) is traditionally divided into infiltrative and encapsulated types. Adding to this classification, noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) represents a reclassification of a subset of cases (encapsulated tumors without lymphovascular or capsular invasion). The purpose of this study was to assess the role of ultrasound (US) in predicting tumor invasiveness in FVPTC.
From January 2014 to May 2016, preoperative US examinations were performed on 151 patients with 152 FVPTCs who underwent surgery. Based on a pathologic analysis, the FVPTCs were categorized into three groups: NIFTP, invasive encapsulated FVPTC (iE-FVPTC), or infiltrative FVPTC (I-FVPTC). Each nodule was categorized based on the US pattern according to the Korean Thyroid Imaging Reporting and Data System (K-TIRADS) and the American Thyroid Association (ATA) guidelines. The correlation between tumor invasiveness and the K-TIRADS or ATA category was investigated using Spearman's rank correlation coefficient.
Among the 152 FVPTCs, there were 48 (31.6%) NIFTPs, 60 (39.5%) iE-FVPTCs, and 44 (28.9%) I-FVPTCs. US characteristics of the FVPTCs differed significantly according to tumor invasiveness (p ≤ 0.030). Tumor invasiveness showed a significant positive correlation with K-TIRADS (tumors of all sizes: r = 0.591, p < 0.001; tumors ≥1.0 cm: r = 0.427, p < 0.001) and ATA categories (tumors of all sizes: r = 0.532, p < 0.001; tumors ≥1.0 cm: r = 0.466, p < 0.001). According to both K-TIRADS and ATA guidelines for all-sized tumors, the most common subtype was NIFTP in low-suspicion nodules (52.6% and 51.6%), iE-FVPTC in intermediate-suspicion nodules (52.7% and 54.2%), and I-FVPTC in high-suspicion nodules (82.5% and 69.4%). After surgery, lymph node metastases were confirmed in two (4.2%) NIFTP cases, three (5.0%) iE-FVPTC cases, and eight (18.2%) I-FVPTC cases (p = 0.001). The results of the BRAF mutation analysis were not significantly different between the groups (p = 0.507).
Increasing tumor invasiveness from NIFTP to iE-FVPTC to I-FVPTC is positively correlated with the level of suspicion on US using both K-TIRADS and ATA guidelines.
滤泡型甲状腺乳头状癌（FVPTC）传统上分为浸润型和包裹型。在此分类基础上，具有乳头状核特征的非浸润性滤泡性甲状腺肿瘤（NIFTP）代表了一部分病例（无血管淋巴管或包膜侵犯的包裹性肿瘤）的重新分类。本研究旨在评估超声（US）在预测 FVPTC 侵袭性中的作用。
2014 年 1 月至 2016 年 5 月，对 151 例接受手术的 152 例 FVPTC 患者进行了术前 US 检查。根据病理分析，FVPTC 分为 NIFTP、浸润性包裹型 FVPTC（iE-FVPTC）或浸润性 FVPTC（I-FVPTC）三组。根据韩国甲状腺影像报告和数据系统（K-TIRADS）和美国甲状腺协会（ATA）指南，根据 US 模式对每个结节进行分类。采用 Spearman 秩相关系数研究肿瘤侵袭性与 K-TIRADS 或 ATA 分类的相关性。
在 152 例 FVPTC 中，48 例（31.6%）为 NIFTP，60 例（39.5%）为 iE-FVPTC，44 例（28.9%）为 I-FVPTC。FVPTC 的 US 特征根据肿瘤侵袭性有显著差异（p≤0.030）。肿瘤侵袭性与 K-TIRADS（所有大小的肿瘤：r=0.591，p<0.001；≥1.0cm 的肿瘤：r=0.427，p<0.001）和 ATA 分类（所有大小的肿瘤：r=0.532，p<0.001；≥1.0cm 的肿瘤：r=0.466，p<0.001）呈显著正相关。根据 K-TIRADS 和 ATA 指南对所有大小的肿瘤，低可疑度结节中最常见的亚型为 NIFTP（52.6%和 51.6%），中度可疑度结节中为 iE-FVPTC（52.7%和 54.2%），高度可疑度结节中为 I-FVPTC（82.5%和 69.4%）。术后证实 2 例（4.2%）NIFTP 病例、3 例（5.0%）iE-FVPTC 病例和 8 例（18.2%）I-FVPTC 病例存在淋巴结转移（p=0.001）。各组间 BRAF 突变分析结果无显著差异（p=0.507）。
从 NIFTP 到 iE-FVPTC 再到 I-FVPTC，肿瘤侵袭性的增加与 K-TIRADS 和 ATA 指南的 US 可疑程度呈正相关。
