Diagnostic performance of thyroid ultrasound in Hürthle cell carcinomas

ABSTRACT Objective Hürthle cell carcinomas (HCCs) of the thyroid have been recently reclassified as a separate entity due to their distinct clinical and molecular profiles. Few studies have assessed the ability of preoperative characteristics in differentiating HCCs from Hürthle cell adenomas (HCAs) due to the low prevalence of both lesions. This study aimed to compare the preoperative features of HCCs and HCAs and evaluate the diagnostic performance of ultrasound in distinguishing between both. Subjetcs and methods Retrospective study including 101 patients (52 HCCs and 49 HCAs) who underwent thyroid surgery from 2000 to 2016. Clinical, ultrasonographic, and histological data were reviewed. Diagnostic performance of suspicious sonographic features was analyzed in 51 cases (24 HCCs and 27 HCAs). Results Hürthle cell neoplasms were predominant in females. Subjects ≥ 55 years represented 58% of the cases of HCCs and 53% of those of HCAs. Carcinomas were significantly larger (p < 0.001), and a tumor size ≥ 4 cm significantly increased the risk of malignancy (odds ratio 3.67). Other clinical, cytologic, and sonographic data were similar between HCCs and HCAs. Among the HCCs, the lesions were purely solid in 54.2%, hypoechoic in 37.5%, and had coarse calcifications in 12.5%, microcalcifications in 8.3%, irregular contours in 4.2%, and a taller-than-wide shape in 16.7%. Predominantly/exclusive intranodular vascularization was observed in 52.6%. Overall, 58% of the HCCs were classified as TI-RADS 4 or 5 compared with 48% of the HCAs. TI-RADS 4 or 5 had a specificity of only 51.8% and a positive likelihood ratio of 1.21. Conclusions Apart from the lesion size, no other preoperative feature adequately distinguished HCCs from HCAs. Sonographic characteristics raising suspicion for malignancy, which are mostly present in papillary carcinomas, were infrequent in HCCs. New tools must be developed to improve preoperative diagnosis and deferral of surgery in cases of adenomas.

摘要
## 研究目的
甲状腺嗜酸性细胞癌（Hürthle cell carcinomas, HCCs）近期因其独特的临床与分子特征，被重新归类为独立病种。由于这两类病变发病率均较低，目前鲜有研究评估术前特征用于鉴别HCC与嗜酸性细胞腺瘤（Hürthle cell adenomas, HCAs）的能力。本研究旨在对比HCC与HCA的术前特征，并评估超声在区分二者中的诊断效能。

## 对象与方法
本研究为回顾性研究，纳入2000年至2016年间接受甲状腺手术的101例患者（其中52例HCC、49例HCA），回顾性分析其临床、细胞学及超声、组织病理学资料。对其中51例患者（24例HCC、27例HCA）的可疑超声特征诊断效能进行分析。

## 研究结果
嗜酸性细胞肿瘤患者以女性居多。≥55岁的患者在HCC病例中占比58%，在HCA病例中占比53%。癌性病灶体积显著更大（p<0.001），且肿瘤直径≥4cm会显著升高恶性风险（优势比3.67）。其余临床、细胞学及超声数据在HCC与HCA间无显著差异。在HCC病灶中，54.2%为纯实性结节，37.5%呈低回声，12.5%伴粗大钙化，8.3%伴微钙化，4.2%轮廓不规则，16.7%呈现纵横比大于1的形态；52.6%的病灶可见结节内主要供血或完全性结节内血管分布。总体而言，58%的HCC被归类为甲状腺影像报告和数据系统 (Thyroid Imaging Reporting and Data System, TI-RADS) 4类或5类，而HCA的这一比例为48%。TI-RADS 4类或5类的特异性仅为51.8%，阳性似然比为1.21。

## 研究结论
除病灶体积外，其余术前特征均无法有效区分HCC与HCA。多数在乳头状甲状腺癌中可见的恶性可疑超声特征，在HCC中并不常见。亟需开发新型工具以提升腺瘤病例的术前诊断效能，并为符合条件的腺瘤患者制定暂缓手术的方案。