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求翻译：AS. The microstructure shall consist of Nodular是什么意思？
AS. The microstructure shall consist of Nodular
问题补充：
as。微观结构应包括结节性
作为。 组成的显微组织球墨铸铁的
AS. 微结构将包括节状
AS 年。Nodular 的包含微观结构
AS.微型结构将包含小节
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请输入您需要翻译的文本！【文摘翻译】 甲状腺结节超声检查:典型图像诊断途径
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【文摘翻译】 甲状腺结节超声检查:典型图像诊断途径
甲状腺结节超声检查典型图像诊断途径Carl C. Reading,MD,* J.William Charboneau,MD,* Ian D. Hay,MD, PhD,† and Thomas J. Sebo,MD‡*Professor of Radiology, Department of Radiology, Division of Ultrasonography, Mayo Clinic College of Medicine, Rochester, M †Professor of Medicine, Department of Medicine, Division of Endocrinology, Mayo Clinic College of Medicine, Rochester, M and ‡Associate Professor of Pathology, Department of Laboratory Medicine and Pathology, Division of Anatomic Pathology, Mayo Clinic College of edicine, Rochester, Minnesota. The authors have disclosed that they have no interests in or significant relationships with any commercial companies pertaining to this educational activity. Wolters Kluwer Health has identified and resolved all faculty conflicts of interest regarding this educational activity. Reprints: Carl C. Reading, Department of Radiology, Mayo Clinic College of Medicine, 200 First St. SW, Rochester, MN 55905 (e-mail: Reading. Carl@mayo.edu).Copyright _ 2005 by Lippincott Williams & WilkinsAbstract: This article describes an approach to some of the commonly encountered, ‘‘classic pattern,’’ appearances of both benign and malignant thyroid nodules that are seen in day-to-day practice. These appearances include specific nodules that commonly need fine needle aspiration (FNA)/biopsy, and other nodules that do not usually need FNA/biopsy.Key Words: Thyroid cancer, thyroid nodule, thyroid ultrasound(Ultrasound Quarterly &#)摘要：这篇文章描述的是我们每日工作中遇到的甲状腺良性和恶性结节典型图像的诊断途径。这些表现包括通常需要细针抽吸(FNA)/组织活检的特殊结节和其它一些通常不需FNA/组织活检的结节。关键词：甲状腺癌，甲状腺结节，甲状腺超声(超声季刊&#)LEARNING OBJECTIVESAfter reading this article and completing the posttest, the reader should be able to_ Describe which thyroid nodules need FNA/biopsy based on their pattern of ultrasound features_ Explain the classic patterns of the ultrasound appearances of typical malignant thyroid lesions_ Explain the classic patterns of the ultrasound appearances of typical benign thyroid lesions学习目的：通过学习这篇文章和完成测试，读者应该能做到－根据超声特征描述，什么类型甲状腺结节需要做FNA/组织活检－解释典型恶性甲状腺病灶的典型超声图像特征－解释典型良性甲状腺病灶的典型超声图像特征
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Thyroid nodules are very common, and are found in 4% to 8% of adults by palpation, 41% by ultrasound, and 50% by pathologic examination at autopsy.1,2 In contrast, compared with the very high prevalence of nodular thyroid disease, thyroid cancer is rare. The American Cancer Society estimates that only 25,690 new cases of thyroid cancer will be diagnosed in the United States this year, which constitutes only 1% of all cancers.3 Of these patients with thyroid cancer, it is estimated that only 1460 will die of their disease this year.4 The challenge of managing thyroid nodules is to reassure the majority of patients who have benign disease and to diagnose the minority of patients who will prove to have malignant disease.Of new cases of thyroid cancer diagnosed in the United States, most (75%–80%) are likely to be papillary thyroid cancer, whereas the remaining histologic types will consist of approximately 10% to 20% follicular, 3% to 5% medullary, and 1% to 2% anaplastic cancers.4,5 The morbidity and mortality rates of thyroid cancer increase with advancing stages of the disease and the age of the patient, but both are low compared with many other cancers.6 It is generally accepted that the overall 30-year survival for papillary carcinoma is approximately 95%.7 The majority of these patients with papillary cancer (80%–85%) is classified as ‘‘low-risk’’, and is associated with 99% survival at 20 postoperative years.8The evaluation of a thyroid nodule depends in part on its method of discovery. If a thyroid nodule is palpable, the evaluation begins with the
if the findings are of concern, the subsequent workup may include laboratory studies, radionuclide scanning, ultrasonography, and/or fine needle aspiration (FNA). If a thyroid nodule is not palpable but detected by imaging, the workup most often either ends with the decision to observe clinically, or proceeds to an FNA, depending on the level of concern based on the imaging appearance or size. Although it is possible for radiologists to simply recommend biopsy of all identified nodules, it is important to become familiar with the morphologic features associated with benign or malignant nodules so that appropriate management recommendations regarding the need for FNA can be made.9 The goal of the pattern-oriented ultrasound approach to the evaluation of both palpable and impalpable thyroid nodules is to understand and recognize the typical appearances of some of the common benign and malignant thyroid nodules and to separate those nodules that usually require FNA for further evaluation from those that usually do not. This article presents an approach to the ultrasound evaluation of thyroid nodules that is used in our practice. It describes the classic appearances of some of the commonly encountered benign and malignant nodules that are seen in day-to-day practice. Although more than half of all thyroid nodules encountered in day-to-day practice will fit into one of the classic categories, this article is not meant to be a complete description of the ultrasound appearances of all conceivable types of thyroid nodule, as many nodules will not fall into one of these specific categories. It is likely that additional classic nodule appearances will be identified over time. Moreover, this article is not meant to be a comprehensive review of the existing and rapidly expanding literature that is developing on this complex subject. Rather, this article describes our current understanding of the sonographic appearances of classic thyroid nodules, and offers what we believe is a practical and effective approach to deal with the large number of thyroid nodules that are encountered in the day-to-day practice of neck ultrasound. These patterns guide our approach, regardless of the size of the nodule, whether the nodule is palpable or not palpable, and whether the nodule is solitary or within a thyroid gland containing multiple nodules. Thus, in a multinodular gland, it is the characteristics of the nodule itself, not its presence in a ‘‘goiter’’ that dictate whether FNA/biopsy is warranted or not. If the nodule has a classic pattern that indicates a benign etiology (Patterns 4 though 8), we do not recommend further imaging, unless there is overriding clinical concern or significant, alarming change in the physical examination during routine clinical follow-up. Almost nothing in medical imaging is absolute, but the eight unique appearances described below, in our experience (which has been gained over the past two decades of practice), are highly likely to represent the pathologic entity described.甲状腺结节十分常见，成人的触及率为4%-8%，超声检出率为41%，尸体解剖检出率为50%[1,2]。相反，与甲状腺结节高发生率来比，甲状腺癌十分罕见。美国癌症学会估计：在美国每年有25,690新病例诊断为甲状腺癌，占所有癌症病例的1%[3]。在所有这些甲状腺癌的病例中，估计有1460病例当年死于甲状腺癌[4]。处理甲状腺结节的挑战是使大多数甲状腺良性疾病的病人安心，诊断出少数甲状腺恶性疾病的病人。在美国诊断甲状腺癌的新病例，大部分(75%–80%)可能是乳头状甲状腺癌，其它组织类型包括近10% -20%滤泡样癌、3% -5%髓样癌和1% -2%未分化癌[4,5]。甲状腺癌发病率和死亡率随着疾病的进展期和病人的年龄而增加，但这两项与其它癌症相比是较低的[6]。一般认为近95%乳头状甲状腺癌有30年的生存期[7]。绝大多数(80%–85%)的乳头状甲状腺癌分类为“低危的”，且99%可术后存活20年[8]。甲状腺结节的评估部分是根据它发现的方法。如果甲状腺结节是可触及的，评估首先是物理检查。发现结节后，接下来进一步检查包括：实验室检查、放射性核素扫描、超声检查和/或细针抽吸(FNA)。如果甲状腺结节不是触及的，而是影像探及，根据影像的特征、大小的倾向，决定是临床观察，还是进行FNA。对放射科医师来说，虽然可以简单的推荐对已证实的结节进行组织活检，但重要的是熟习良性和恶性结节的形态特征，以便对是否需要FNA提出适当的处理意见[9]。用超声图像导向方法，评价可触及和未触及甲状腺结节的目是：领会和识别常见甲状腺良性和恶性结节的典型特征，区分哪些结节通常需要进一步FNA的评估，哪些结节通常不需要。本文所提出的甲状腺结节超声评估方法是我们在实际中所应用的。描绘了我们日常工作中所见到的甲状腺良性和恶性结节的典型表现。虽然一半以上的甲状腺结节可以归入这些分类之一，但这篇文章并不意味着完全描述所有甲状腺结节可能类型的超声特征，因为有很多结节不能归入这些特殊的分类。随着时间的推移，很可能有其它典型结节表现被证实。此外，对这个发展中的复杂科目，本文并不是对现有和大量新发表文献的广泛综述。这篇文章所描述的是我们对典型甲状腺结节超声表现的现行理解，提供对日常颈部超声检查工作中所遇见的大量甲状腺结节，我们认为可行且有效的处理方法。无论甲状腺结节的大小、是否可触及、单发还是多发，这些模式指导我们的处理方法。因此，在多结节的腺体中，结节本身有其特点，据此决定是否进行FNA/组织活检，而不是根据甲状腺否是肿大。如果结节有良性病原学的典型模式(模式5-8)，建议不用进一步影像检查，除非在临床随访的物理检查时有重叠的临床疑问或显著的改变。几乎没有临床影像是绝对的，但是在以下所描写的8项独特特征，在我们二十年的经验中，很可能代表着病理学本质的描述。
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THYROID NODULES THAT COMMONLY NEED FINE NEEDLE ASPIRATION/BIOPSYA solid, hypoechoic nodule containing discrete echogenic foci is papillary carcinoma with a high probability (Fig. 1). Thyroid carcinomas are divided into four principal primary epithelial histologic types: papillary, follicular, medullary, and undifferentiated. Papillary carcinoma is the most common malignancy of the thyroid, comprising 75% to 80% of all new diagnoses of thyroid cancer.10,11Most papillary carcinomas (63%–90%) are hypoechoic in echogenicity relative to thyroid parenchyma.12,13 This finding holds true even for small papillary cancers, where Papini found that 87% of nonpalpable (8–15 mm) thyroid cancers were hypoechoic.14 However, at the same time, 55% of benign nodules can be hypoechoic.12 Therefore, the presence of significant additional sonographic features is important to help discern which nodules are most likely to be malignant. The most useful additional sonographic finding that suggests malignancy is the presence of microcalcifications, which are seen as several or many discrete highly echogenic foci. Both coarse calcifications and microcalcifications may be detected in malignant nodules, with microcalcifications being more specific for thyroid cancer.15 The appearance of microcalcifications is highly specific for malignancy with a sonographic specificity of 93% to 95%.14,16 The sensitivity is lower at 29% to 59%.12,16,17 The prospective positive predictive value of these calcifications for malignancy has been reported to be 70% to 71%.15,17Calcium deposits are frequently identified during pathologic microscopic evaluation of papillary cancer. They may be due to either psammoma bodies, or coarse granular amorphous deposits of calcification.15 Psammoma bodies are tiny calcified laminated spherules found in 40% to 61% of papillary cancers.18,19 They are thought to be due to necrotic cells, often at the tips of papillae, which form a nidus for subsequent concentric laminations of calcium. Amorphous deposits of calcification can also occur in papillary carcinoma. These irregular, coarse deposits are typically present in areas of fibrosis and degeneration.Holz and Powers20 reported in 1958 that the x-ray finding of fine stippled calcification within a thyroid mass was characteristic of papillary thyroid carcinoma. A similar appearance has subsequently been visualized on ultrasound and has been confirmed by many other authors since this time. It is now well accepted as a worrisome finding for malignancy.16,21 These tiny calcifications usually do not cause acoustic shadowing when widely scattered, but may cause shadowing in some cases, perhaps when clustered in an aggregate. 通常需要细针抽吸/组织活检甲状腺结节实质性低回声结节，内见散在的灶性回声高度可能为乳头状癌(图1)。甲状腺癌分为四种基本上皮组织类型：乳头状的、滤泡状的、髓样的和未分化的。乳头状癌是甲状腺最常见的恶性肿瘤，占所有甲状腺癌诊断的75% - 80%[10,11]。大部分乳头状癌(63%–90%)相对甲状腺实质为低回声[12,13]。这些发现甚至适用于小的乳头状癌，Papini发现87%的未触及的甲状腺癌(8–15 mm)为低回声[14]。然而同时55%的良性结节也是低回声[12]。因此，其它特异的超声表现对于识别恶性结节是非常重要的。最有用的恶性附加超声表现是微钙化的存在，可见数个或许多分离的高回声灶。在恶性结节中可探及粗糙的钙化和微钙化，而微钙化在甲状腺癌中更有特异性[15]。微钙化的表现在恶性肿瘤有高度特异性，超声特异性为93%-95%[14,16]，而敏感性低于29% ¬-59%[12,16,17]。这些钙化对恶性肿瘤阳性预测值报导为70%-71%[15,17]。钙沉着在乳头状癌显微镜病理学估价中经常可见。它们可能是由于砂砾体或粗糙无定形颗粒的钙质沉积[15]。砂砾体是微小层状钙化小球，在40%-61%的乳头状癌可见[18,19]。它们被认为是细胞坏死引起，通常在乳头的顶部，形成巢状，继而形成同心层状构造钙化。Holz和Powers[20] 1958年报导X线发现，甲状腺肿块内细小斑点状钙化是甲状腺乳头状癌的特征。接下来是超声检查可见类似特征，此后被许多著者所证实。现被广泛接受，是恶性肿瘤是征象[16,21]。当这些细小钙化广泛散在时，通常无声影，但在一些病例中，当钙化成簇聚集时也可引起声影。FIGURE 1. Classic Pattern #1. Papillary Carcinoma: Transverse sonogram of isthmus shows solid, hypoechoic nodule (arrows) containing fine internal calcifications (arrowhead).图1典型模式一，乳头状癌：峡部横切面超声图显示实性、低回声结节(箭头示)，内见细小钙化点(短箭头)。
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A solid, hypoechoic nodule with coarse echogenic foci may represent either medullary carcinoma or papillary carcinoma (Fig. 2). Almost all medullary cancers are hypoechoic. They tend to be well marginated sonographically, which reflects their usual gross morphologic appearance—sharply circumscribed although not encapsulated. They are usually soft, but may be firm and sclerotic. Medullary cancer is much less common than papillary cancer and accounts for 3% to 5% of all thyroid cancers. In 20% of cases it is familial and often associated with MEN-2 syndrome where it is often multicentric and bilateral. Medullary carcinoma is sporadic and usually solitary in the remaining 80% of cases. Because it originates from the C-cells of the thyroid, it is often located in the upper and mid portions of the thyroid lobes because this is where the majority of the C-cells are located. Coarse calcifications are often seen in these tumors, and the calcifications often tend to be more discretely and centrally located than in papillary cancers. However, because papillary cancer is much more common than medullary cancer, the finding of coarse calcifications within a hypoechoic nodule will also frequently be due to papillary cancer. Amyloid deposits are often present microscopically secondary calcification and fibrosis within the amyloid deposits may represent the origin of the sonographically visualized coarse echogenic foci.22 In addition, medullary cancer may rarely contain psammoma bodies, which can be another cause of visualized echogenic foci. Coarse, dense nodular calcification can occur in benign nodules as well as malignant ones. Calcification within benign multinodular goiter is common, and the incidence of calcification seems to increase with the duration of the goiter.23,24 This is thought to be due to dystrophic calcification. Several authors have stressed that this pattern of coarse calcification cannot be used to distinguish between malignant and benign thyroid lesions.21 However, in our opinion, the combination of coarse calcification within the central portion of a hypoechoic nodule is worrisome and warrants FNA.实性低回声结节有粗糙的回声点可代表是髓样癌或乳头状癌(图2)。几乎所有的髓样癌都是低回声的。它们超声表现倾向于边界清晰，这反应了它们通常是粗大是形态学表现――虽然没有包膜，但界限分明。它们通常是柔软的，但也可以是坚固和骨质的。髓样癌较乳头状癌少见，约为所有甲状腺癌的3%－5%。20%的病例有家族性，常伴有MEN-2综合征，通常是多中心和双侧的。髓样癌是散发的，80%的病例通常是单个病灶的。其起源于甲状腺C细胞，通常位于甲状腺的中上部，因为大部分C细胞位于此。这些肿瘤中常见粗糙的钙化，通常比乳头状癌倾向于更独立和位于中心。然而，因为乳头状癌较髓样癌更常见，因此低回声结节内粗糙钙化的发现更倾向于乳头状癌。显微镜下淀粉样沉着物常存在于髓样癌；淀粉样沉着物内继发性钙化和纤维化是超声所见的局灶性粗糙回声[22]。此外，髓样癌罕有砂砾体，此是引起局灶性回声的另一原因。粗糙的高密度结节性钙化可发生在良性结节，也可发生在恶性结节。钙化在多结节甲状腺肿是常见的，甲状腺肿大期间钙化的发生率似乎增加[23,24]这被认为是由于营养不良性钙化。一些作者强调这种粗糙类型的钙化不能用于区分甲状腺病灶的良恶性[21]。然而，我们的意见是结合低回声结节中心部分粗糙的钙化是令人担忧的，是进行FNA的证据。FIGURE 2. Classic Pattern #2. Medullary Carcinoma: Longitudinal sonogram of the thyroid shows a solid, hypoechoic nodule with coarse calcifications.图2典型模式二，髓样癌：甲状腺纵向声像图显示一个实性、低回声结节伴粗大钙化。
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A solid, homogeneous, egg-shaped nodule with a thin capsule indicates follicular neoplasm with a high probability (Fig. 3). Most follicular neoplasms are solid and in 70% of cases, they are homogeneous in echogenicity. 13 They can be isoechoic, hyperechoic, hypoechoic, or mixed. Their shape is usually ovalor round and the sonographic appearance is very similar to a normal testicle. A thin hypoechoic halo is present in 80% of cases.13 Small focal cystic components may be present. Calcification is rare. Vascularity is usually diffusely increased throughout the nodule.Follicular neoplasms may be due to either benign follicular adenoma or malignant follicular carcinoma. The term ‘‘neoplasm’’ technically simply means that the mass in question is derived from a single cell line. Some have used the term ‘‘follicular lesion’’ rather than follicular neoplasm, because the term neoplasmis often misinterpreted as malignant carcinoma.13In our experience, most (85%) follicular neoplasms are benign adenomas. The distinction of encapsulated follicular carcinoma from follicular adenoma rests exclusively on the pathologic demonstration of capsular or vascular invasion or both. This distinction cannot be made by imaging features, and also, importantly, cannot be made by FNA or large core needle biopsy. Unfortunately, surgical excision is necessary to exclude the uncommon follicular carcinoma. The pathologist subsequently examines the gross specimen to determine if the malignant features of microscopic capsular or vascular invasion are present. If these pathologic features are not present, the lesion is considered to be a benign follicular adenoma.Pathologically, follicular neoplasms typically have well developed continuous capsules, a uniform internal structure, increased vascularity, sharp demarcation, and distinct structural difference from, and compression of, surrounding thyroid tissue, which correlates well with their sonographic appearance. In contrast to follicular neoplasms, benign, non-neoplastic hyperplastic nodules (also called colloid or adenomatoid nodules), which are by far the most common source of thyroid nodules, are poorly encapsulated, of variable internal structure, and often merge into the surrounding thyroid tissue. However, some benign hyperplastic nodules in nodular goiter can demonstrate and fulfill the criteria for adenoma and therefore, simulate this entity, pathologically. In theory, if molecular genetic studies are performed on the resected nodule specimens they will show that nodules in nodular goiter are usually polyclonal, whereas carcinomas and adenomas are monoclonal.However, some nodules in nodular goiter ar so, the practical utility of this analysis is unclear. Consequently, some pathologists prefer to classify these hyperplastic nodules as adenomatoid nodules or adenomatoid goiter. Therefore, it should not be surprising that in some cases the sonographic differentiation of these two entities can also be difficult.There are several pathologic subtypes of follicular adenoma. Simple adenomas (colloid or macrofollicular) are the most common, and are composed of relatively large follicles with abundant colloid. Microfollicular lesions are comprised of less colloid and have compact follicular structures. Finally fetal or embryonal lesions often have little, if any, colloid or follicular architecture. Oxyphil (oncocytic, Hu¨ rthle cell) adenomas are usually regarded as variants of follicular adenomas, but are considered separate entities by some, because they may have a higher risk of malignancy and more aggressive biologic behavior than other follicular neoplasms.25The risk of a thyroid adenoma undergoing malignant change is not well defined. There is no obvious adenoma carcinoma sequence as has been well established in other malignancies like colon cancer.25 The larger the size of the follicular nodule, however, the greater the chance of finding malignant regions within it.Cytologic interpretation of FNA of nodules with the classic homogeneous, egg-shaped ultrasound pattern most often will be interpreted as ‘‘suspicious’’, consistent with follicular neoplasm. In most of these cases, surgical excision is recommended. Less often the cytologic interpretation will be either ‘‘negative’’, consistent with benign nodule, or ‘‘positive’’, consistent with papillary carcinoma. If the FNA specimen is interpreted as negative, further work-up is typically not warranted, unless there is an obvious discrepancy between the cytologic interpretation and the ultrasound findings. False negative FNA exams, although rare, can occur. False-negative cytologic results are probably due to biopsy of the macrofollicular variety of follicular neoplasm, which does not have significant malignant potential, and therefore the cytologic designation as negative or benign is warranted.Infrequently, FNA of a nodule with the sonographic appearance of follicular neoplasm will be interpreted as positive for papillary carcinoma. This is usually due to a unique type of papillary carcinoma called the follicular variant of papillary cancer. This variant is often encapsulated and is composed entirely, or almost entirely, of follicles.26实性、回声均匀、有薄包膜蛋形结节，高度可能性为滤泡性新生物(图3)。大多数滤泡性新生物为实性，70%的病例回声均匀[13]。可为等回声、高回声、低回声和混合性回声。通常为椭圆形，超声特征与正常睾丸极为相似。80%的病例存在薄的低回声晕[13]，可有小的局灶性囊性成分，钙化罕见。通常整个结节弥漫性血管增加。滤泡性新生物可为良性的滤泡状腺瘤或恶性的滤泡状腺癌。学术上的“新生物”只代表现在讨论的肿块，由单细胞分化而来。一些人使用“滤泡状病灶”而不是滤泡性新生物，因为新生物这个名词经常误认为是恶性癌[13]。以我们的经验，大部分(85%)滤泡状新生物是良性腺瘤。有包膜的滤泡状腺癌和滤泡状腺瘤区别是包膜病理学显示的独特架构或血管的侵袭或两者同时存在。这个区别不可能在影像上显示，同样重要的是不可能在FNA或粗针组织活检显示。不幸的是，必须外科切除排除少见的滤泡状癌。病理学家随后的大体标本研究确定是否有显微镜下包膜的恶性结构或血管侵袭的存在。如果这些病理结构不存在，病灶被认为是良性的滤泡状腺瘤。从病理学上来看，典型的滤泡性新生物有发育良好的连续的包膜、内部结构均匀、血管增多、边界清晰，与周围组织结构完全不同，对周围局灶性组织有压迫，与超声声像图特征有良好的相关性。对比滤泡状新生物，良性的、非新生物的增生结节(也称为胶质或腺瘤样结节)，为最常见的甲状腺结节，其缺乏包膜、内部结构多变、散在周围的甲状腺组织中。然而，在结节性甲状腺肿中的一些良性的增生结节可显示为腺瘤的特征，因此病理上类似。从理论上，如果将切除的结节标本从分子遗传学上研究，将显示结节性甲状腺肿中的结节通常是多克隆的，而癌和腺瘤是单克隆的。然而，结节性甲状腺肿中的一些结节同样是单克隆的；因此这些分析实际意义并不明朗。作为结果，一些病理学家倾向于将这些增生结节分类为腺瘤样结节或结节性甲状腺肿结节。因此，这两种病例的超声鉴别诊断上同样是困难的。滤泡性腺瘤存在一些病理亚型。单纯型腺瘤(胶质或巨大滤泡)是最常见的，包括相对较大的、富含胶质的滤泡。微滤泡病灶包含少量胶质和具有致密的滤泡结构。最终胎儿或胚胎性病灶通常很少有胶质和滤泡结构。嗜酸性细胞(嗜酸瘤细胞的，Hu¨ rthle 细胞) 腺瘤通常被认为是滤泡性腺瘤变异体，但是一些人认为是分离的实体，因为它们高危为恶性肿瘤，比其它滤泡性新生物更具有生物攻击行为[25]。甲状腺腺瘤恶变的危险不是十分确定。没有明显的腺瘤――癌变的顺序变化，不像其它恶性肿瘤如结肠癌已经确定[25]。然而，滤泡状结节越大，在其内发现恶性区域的机率越大。典型的回声均匀、卵形超声表现的结节FNA细胞学分析绝大部分被认为是可疑的，此与滤泡性新生物相一致。这些病例大部分被建议外科切除。通常很少细胞学判读为：阴性符合良性结节或阳性符合滤泡状癌。如果FNA标本判读为阴性，没有理由进一步检查，除非细胞学判读和超声表现有显著的差异。FNA检查假阴性虽然少见，但也可发生。细胞学假阴性的结果很可能是由于滤泡状新生物组织活检巨大滤泡的变异，没有显著恶性的可能性，因此细胞学指示为阴性或良性。罕有滤泡性新生物声像图特征的结节FNA细胞学判读为乳头状癌阳性。这通常为乳头状癌独一无二的类型称做乳头状癌滤泡状变异。这种变异通常是有包膜的，全部或几乎全部由滤泡组成[26]。FIGURE 3. Classic Pattern #3. Follicular Neoplasm: Longitudinal sonogram of the thyroid shows a solid, homogeneous, egg-shaped nodule with a thin capsule.图3 典型模式3：滤泡状新生物：甲状腺超声纵切面显示一个实性、回声均匀、蛋形结节，有薄包膜。
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A refractive shadow from the edge of a solid lesion is worrisome for malignancy (Fig. 4). Grossly, papillary thyroid cancer frequently contains abundant amounts of reactive fibrous connective tissue, particularly at the periphery or advancing edge of the tumor. In one series of gross specimens, fibrous connective tissue was present in 56% of papillary cancers.27 It may be that this dense fibrotic reaction at the edge of the thyroid cancer causes the sonographic refractive shadow.Refraction occurs when sound passes from a tissue with one acoustic propagation velocity to a tissue with a faster or slower sound velocity. When the ultrasound beam intersects a boundary interface at an oblique angle there is refraction of the beam resulting in a change in the direction of the sound wave. This causes lack of transmission posterior to this site, and the critical angle refraction causes shadowing deep to the oblique interfaces. Although unproven, it may be that the refractive shadow at the margins of some thyroid cancers is due to fibrosis or encapsulation. It is important to know that refractive shadows can also occur deep to the border of predominantly cystic nodules and, in that setting, the finding is not worrisome for malignancy.There is considerable variability in the sonographic descriptions of both the contour and margin of thyroid cancer in the existing literature. A halo, often incomplete, has been described as occurring in 15%to 30%of papillary carcinomas.13 Thyroid malignancies have been variably described as having both irregular and smooth contours, and having both poorly defined and well-defined margins. 17,28,29 Pathologic studies of lesion morphology suggest that papillary cancer can cause all of these patterns. The typical papillary cancer invades into the surrounding thyroid parenchyma without a well-defined capsule. However, in 22% of cases, portions of a gross capsule or fibrous connective tissue can be detected, and there is total or complete encapsulation of papillary thyroid cancer in 4% to 16% of lesions.18,30,31实质性病变的侧壁声影是恶性表现(图4).粗大的乳头状甲状腺癌经常富含大量的反应性纤维结缔组织，特别是在肿瘤的周边或近边缘。在一系列大体标本中，56%的乳头状癌存在结缔组织[27]。甲状腺癌边缘的高密度纤维变性反应引起侧壁声影。当通过声波传播速度不同的组织时(或快或慢)，声波发生折射。声束通过边界斜角界面时，声波发生折射而改变传播方向。此处后方缺乏声束传播，折射临界角引起声影深至斜角界面。虽然一些甲状腺癌边界引起折射声影，但没有证实是由纤维化或包膜引起。重要的是知道折射声影同样可发生在大部分囊性结节的边缘深面，在这种情况下就不是恶性表现。在现有的文献中，对甲状腺癌轮廓和边界的超声描述有相当大的差异。声晕通常不完全有，乳头状癌发生率约15%-30%[13]。甲状腺恶性肿瘤可描述为不规则或光整的轮廓，边界清或不清[17,28,29]。病灶的形态学病理研究认为乳头状癌各型均可有。典型的乳头状癌无界限清楚的包膜，侵入周围的甲状腺实质。然而22%的病例，粗大的包膜和纤维结缔组织部分可有探及，乳头状癌仅有4%-16%的病灶有完整的包膜[18,30,31]。FIGURE 4. Classic Pattern #4. Papillary Carcinoma: Longitudinal sonogram of the thyroid shows refractive shadows from the edge of a solid mass. Note internal microcalcifications.图4典型模式#4。乳头状癌：甲状腺超声长轴观显示实性肿块边缘的折射声影。注内部微钙化。
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NODULES THAT DO NOT USUALLY NEED FINE NEEDLE ASPIRATION/BIOPSY通常不需要细针抽吸/组织活检的结节Small cystic nodules, with or without internal echogenic foci, indicate benign non-neoplastic nodules (Fig. 5).Small, less than 1 cm, solitary or multiple fluid-filled nodules are most often caused by benign thyroid nodular hyperplasia with colloid filled cysts. It is doubtful that these cysts represent dilated follicles because normal follicles within the thyroid are typically about 0.2 mm in size.32,33 Normal follicles can change in size based on the functional activity of the gland but rarely are larger than several millimeters in diameter.Often there are tiny echogenic foci with comet-tail or ring-down artifacts within the cystic nodules. Some authors have concluded that this is due to condensed colloid.16,21 In one sonographic series of 100 nodules that exhibited comettail artifacts, all of the nodules were benign and no malignancy was seen.34 The authors concluded that this artifact is seen in association with abundant colloid, and abundant colloid is usually present in benign nodules.Most nodules of the thyroid are not true neoplasms, but are benign hyperplastic nodules. These form as a result of cycles of hyperplasia and involution of the thyroid parenchyma. The definition of the term “goiter”means enlargement of the thyroid, and it does not technically distinguish among enlargement due to solitary neoplastic, hyperplastic, or or benign or malignant etiologies. In day-to-day use, however, “goiter” is most commonly used to describe a ‘‘simple goiter’’ that is a noninflammatory, non-neoplastic, diffuse, or nodular enlargement of the thyroid without hyperthyroidism (non-toxic).The natural history of simple goiter is assumed to be a diffuse hyperplasia that later becomes nodular.25 The first phase of diffuse enlargement is termed parenchymous goiter. Over time excessive colloid is stored and a diffuse colloid goiter results. The nodular goiter phase develops due to repeated cycles of exacerbation and remission with resultant increasing fibrosis, nodularity, hemorrhage, cystic degeneration, and calcification. These cystic areas contain colloid or brown fluid containing blood products. Large nodules tend to compress the surrounding parenchyma and may have partially developed fibrous capsules. For the most part, these nodules are incompletely encapsulated, are poorly demarcated, and merge with the internodular tissue, which also has an altered architecture. However, in some glands, the lesions are localized and there are areas of apparently normal architecture elsewhere in the gland. This is most commonly termed nodular goiter at this phase.小囊性结节，有或无内部回声点，表明是良性非新生物结节(图5)。小于1cm或多发充满液体的结节是最常见的良性甲状腺结节，伴有内充满胶质的囊肿。对这些囊肿是扩张的滤泡仍有疑问，因为甲状腺内正常滤泡典型的约为0.2mm[32,33]。正常滤泡大小的变化是根据甲状腺功能活动，但少有直径超过数毫米。通常囊性结节内的微小灶性回声伴有彗星尾征或环状伪影。一些作者的结论是胶体浓缩引起[16.21]。在100个存在彗星尾征结节的超声研究中，所有的结节均是良性，无恶性所见[34]。这些作者的结论是：这种伪像与富含胶质相关，富含胶质通常存在于良性结节。甲状腺内大部分结节不是新生物，而是良性增生结节。是由于循环增生和甲状腺实质退化所引起。甲状腺肿的定义是甲状腺增大，由单发或多发结节的、新生物的、增生的或炎性的，或是良性或恶性病因引起的增大没有学术上的区别。然而我们日常使用的甲状腺肿最常用来描述单纯性甲状腺肿，是非炎性的、非新生物的、弥漫性的或是结节性增大，而没有甲状腺功能亢进(非毒性的)。单纯性甲状腺肿的自然病史被认为是弥漫性增生，以后转变成结节[25]。弥漫性增大的第一期叫做实质甲状腺肿。随着时间的推移更多的胶质积存形成弥漫性胶样甲状腺肿的结果。由于纤维变性、结节化、出血、囊性变和钙化的加重及缓解的反复循环而发展至结节性甲状腺肿期。这些包含胶体或棕色液体囊性区包含出血产物。大结节压迫周围的实质，部分形成纤维包膜。绝大部分是包膜不完整，分界不清，合并在结节组织内，同样有结构的改变。然而，在一些腺体内，病灶是局限的，腺体的其它部位表面上是正常的结构。在此期最常称为是结节性甲状腺肿。Classic Pattern #5. Benign, small non-neoplastic nodules: Longitudinal sonogram of the thyroid shows small cystic nodules with internal echogenic foci with posterior reverberation, ‘‘comet-tail,’’ artifacts (arrow).图5. 典型模式#5。良性、小的非增生结节：甲状腺超声纵切面观显示小的囊肿结节，伴结节内局灶性回声及其后方反射――彗星尾征(箭头示)。
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A nodule containing multiple cystic spaces separated by thin septations in a ‘‘honeycomb’’ pattern strongly indicates a benign, non-neoplastic, nodule (Fig. 6). Fluid-filled nodules with thin internal septations are most likely benign nodules due to hyperplasia. They are heterogeneous in appearance with multiple thin internal septations or attenuated strands of thyroid tissue within the fluid. They are typically avascular with Doppler imaging.35 Careful scanning with high-frequency transducers is necessary. In some cases these honeycomb cystic nodules have specular, often linear, echogenic foci that are due to the back wall interfaces of the internal cystic components. These should not be mistaken for hypoechoic solid nodules with malignant microcalcifications. The difference between these two entities rests in the recognition of the presence, or absence, of internal fluid components and the location of the echogenic foci associated with the back wall of the cystic space. This is in contrast to malignant nodules, which are typically solid, where the malignant coarse and micro-calcifications are located within the solid stroma of the malignant nodules. Sometimes these benign honeycomb cystic nodules have echogenic foci with comet-tail artifacts that are seen within the fluid components. These features may only be visible transiently during real-time imaging and may not be apparent on review of static images. Therefore, careful real-time evaluation is critical.多囊性结节，有薄的分隔，呈蜂窝状。强烈预示着是良性。非新生物结节(图6)。内部有分隔充满液体的结节最有可能是良性结节，是由增生引起。它们的超声表现为回声不均匀、内部有分隔或甲状腺组织内衰减带为液体。多普勒为典型的无血管影像[35]。用高频探头仔细检查是必要的。一些蜂窝状囊性结节有镜像反射，通常是线性的、灶性回声,是由囊肿内部成分后壁界面。不应该认为是低回声实性结节伴恶性的微钙化。不应该误认为是有恶性微钙化的低回声实性结节。这两种实质的区别是在于识别内部是否存在液体成分，局灶性回声位置是否与囊性空间的后壁有关。这与恶性结节完全不同，为典型的实性、恶性粗糙和微钙化位于恶性结节的实性间质内。时常这些良性蜂窝状结节有局灶性回声伴在液体成分内彗星尾征的伪像。这些特征仅在实时检查时瞬时可见，在静态显像回放是并不明显。因此仔细实时评估是非常重要的。FIGURE 6. Classic Pattern #6. Benign, non-neoplastic nodule: Longitudinal sonogram shows a nodule containing multiple cystic spaces separated by thin septations in a ‘‘honeycomb’’ pattern.图6典型模式#6。良性、非新生物结节：超声纵切面显示多囊性结节，有薄的分隔，呈蜂窝状。
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A large, predominantly cystic nodule is highly likely a benign non-neoplastic nodule (Fig. 7).In two recent studies 40% to 53% of all benign nodules contained cystic components.36,37 These cystic nodules are benign non-neoplastic hyperplastic nodules often containing a large cystic component due to degeneration with associated fibrosis and avascular internal debris.Malignant nodules, however, rarely undergo a large amount of cystic change detected sonographically. Papillary cancers have been reported to have cystic components in 13% to 25% of cases, and the cystic component is usually very small.29,38 In our experience, it is rare for carcinomas to have a significant or large cystic component and only 2.5% of cancers have a sonographically visualized large cystic component of more than half of the volume of the tumor.39Even if a cancer is predominantly cystic, other worrisome features such as microcalcifications are often present and careful scanning to evaluate the specific features of the solid component is important. The solid component may appear as a papillary projection into the fluid or as an irregular nodular or shaggy interface with the fluid.18 Hatabu et al40 described the sonographic findings of solid excrescences containing multiple punctuate echogenic foci protruding into the fluid, also called a ‘‘calcified nodule within a cyst’’ sign, and reported a 100% correlation between this sign and papillary carcinoma in a series of eight patients.Fine needle aspiration could be performed on these cystic nodules but it would likely often be non-diagnostic due to the large amount of fluid and the small number of diagnostic follicular cells present. The nature of the fluid obtained in aspiration of both benign and malignant cystic lesions is similar in appearance. In one study of cystic thyroid nodules, bloody fluid was aspirated in 80% of malignant lesions, 88% of benign neoplastic lesions, and 78% of benign non-neoplastic lesions. Although aspiration of most cystic papillary cancers in this series yielded bloody or brown fluid, one cancer contained clear yellow fluid.38 If the appearance of the solid component is worrisome, directed aspiration of the mural nodule should be performed.Of interest, cystic changes of papillary carcinoma are often more common and more extensive in cervical lymph node metastases than
43% to 70% of metastatic nodes from papillary carcinoma have fluid components detected sonographically.41–43 The node morphology may exhibit the opposite cystic characteristics from the primary tumor. In one study, only 20% of metastatic nodes had cystic changes when the primary tumor was predominantly cystic, but 34% of metastatic nodes had cystic changes when the primary tumor was completely solid.27大的主要为囊性的结节很可能是良性非新生物结节(图7)。最近两项研究表明，所有良性结节中有40%-53%包含有囊性成分[36,37]。这些囊性结节是良性非新生物增生结节，通常包含有较多的囊性成分，是由于退行变性伴有纤维化和内部无血管的碎屑。然而，恶性结节很少超声探及较大量的囊性变。仅有13%-25%乳头状癌报导有囊性成分，囊性成分通常很小[29,38]。罕有癌肿有显著或较大的囊性成分，仅2.5%的病例超声探及较大的囊性成分，超过瘤体积的一半[39]。即使癌肿大部分为囊性，但其它一些特征如微钙化通常存在，仔细检查评估实性成分的特征是重要的。实性成分可表现为乳头突入液体、或不规则结节及凹凸不平实质与液体的界面[18]。Hatabu[40]等描述实性赘疣的超声表现，包括多发、明显的局灶性回声突入液体，也称为囊内“钙化结节”征，在8例报导中，100%的此征与乳头状癌相关。这些囊性结节可进行FNA，但是由于液性体积较大，很可能没有诊断，少数诊断为存在少量滤泡细胞。良性及恶性囊性病灶包含液体的性质外表上看相似，在一项甲状腺囊性结节的研究中，80%的恶性病灶、88%良性新生物病灶和78%良性非新生物病灶抽吸为血性液体。虽然在大部分囊性乳头状癌的抽吸液为血色或棕色液体，但一例为澄清的黄色液体[38]。如果实性成分有恶性表现，应该定向进行囊壁结节抽吸术。有趣的是，在乳头状癌中，囊性变在颈部转移淋巴结较原发性肿瘤更常见更广泛；43% ¬- 70%的乳头状癌转移灶超声探及液性成分[41-43]。转移淋巴结形态学可表现为原发性肿瘤的相当囊性特征。一项研究表明，原发性肿瘤主要为囊性时，仅有20%转移灶为囊性变，但原发性肿瘤完全为实性时，34%转移灶为囊性变[27]。FIGURE 7. Classic Pattern #7. Benign, non-neoplastic nodule: Transverse sonogram shows a large predominantly cystic nodule. C, c Tr, tracheal gas shadow.图7典型模式#7。良性、非新生物结节：超声横切面显示一个大的主要是囊性回声结节。C颈总动脉；Tr,气管气影。
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Innumerable tiny hypoechoic nodules in both lobes almost certainly indicate Hashimoto’s thyroiditis (Fig. 8). Of the inflammatory diseases of the thyroid, Hashimoto’s thyroiditis is the most common. Hashimoto’s thyroiditis is also the most common cause of hypothyroidism. It is an autoimmune disease where antibodies develop to both thyroglobulin (Tg) and the thyroid peroxidase (TPO) enzyme. It is four times more common in women than men, and has a prevalence of 4% of the female population. The sonographic appearance of Hashimoto’s thyroiditis is often one of innumerable small hypoechoic nodules. The nodules range in size from 1 to 6 mm, are of similar hypoechoic appearance, and occur bilaterally. Coarse hyperechoic septations or bands may be present. The internal blood flow of the parenchyma of the gland may be increased, normal, or decreased. Grossly, the gland is typically symmetrically enlarged and contains visible discrete nodules. Microscopically, there is diffuse infiltration of the thyroid parenchyma by lymphoplasmacytic infiltrates, which form lymphoid follicles, and varying amounts of fibrosis, which account for the sonographic nodular and hyperechoic band features.When these typical sonographic features are present, the positive predictive value of sonography in the diagnosis of Hashimoto’s thyroiditis was 95% in one series.44 It was also of interest in this series that 75% of the patients had no known diagnosis of thyroiditis before the ultrasound examination. In clinical practice, this diagnosis is often made by the ultrasound examination without clinical suspicion. The diagnosis of Hashimoto’s thyroiditis is usually confirmed by serologic tests, including anti-Tg and anti-TPO antibodies, rather than FNA.双侧数不清的小低回声结节，几乎可以确定为桥本氏甲状腺炎(图8)。甲状腺炎性疾病，桥本氏甲状腺炎最为常见。桥本氏甲状腺炎是甲状腺机能减退最常见的原因。是自身免疫性疾病，抗体为甲状腺球蛋白(Tg)和甲状腺过氧化物酶(TPO)。女性是男性的四倍，女性的发生率为4%。桥本氏甲状腺炎的超声表现通常是双侧数不清的小低回声结节。结节大小在1 - 6 mm，均为类似的低回声。粗糙的高回声间隔或光带。甲状腺实质内部血流可增加、正常或减少。大体上看，腺体为典型的对称的增大，内见分离的结节。显微镜下观，甲状腺实质内可见淋巴细胞和浆细胞浸润，形成淋巴样滤泡，不同程度的纤维化，此可解释超声的结节和高回声带结构。在一项研究中，当存在典型的超声表现时，桥本氏甲状腺炎诊断的阳性预测值为95%[44]。同样有趣的是在超声检查以前75%的病人未知甲状腺炎的诊断。在临床实践中，在没有临床怀疑下，通常是超声做出诊断。桥本氏甲状腺炎诊断通常是血清学试验包括抗Tg和抗TPO抗体，甚至FNA所证实。FIGURE 8. Classic Pattern #8. Hashimoto’s thyroiditis: Longitudinal sonogram shows multiple tiny hypoechoic solid nodules (arrow) and coarse echogenic bands (arrowhead).图8典型模式#8。桥本甲状腺炎：超声纵切面观显示多发小的低回声实性结节(箭头示)和粗糙的带状回声(小箭头示)。
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A wide variety of pathologic conditions, including neoplastic, hyperplastic, and inflammatory diseases can all cause nodular enlargement of the thyroid. All of these conditions can have a spectrum of appearances that can overlap with one another. Fortunately, in our experience, there are some appearances that strongly indicate the underlying pathologic nature of the lesion. This classic pattern approach to thyroid nodule evaluation has allowed us to avoid unnecessary and costly workup including additional imaging, FNA, and surgical removal. In medicine, every decision to either stop a workup or pursue with further workup is based on a balance of perspectives and clinical judgment. For example, mammographers will frequently diagnose a benign fibroadenoma of the breast based on its imaging features. This diagnosis is highly probable but not absolutely certain without surgical removal and pathologic study (ie, the imaging diagnosis is highly likely but not certain). In addition, the perspectives must include not only the cost of missing a cancer but also the cost of aggressively managing a mass that is not cancer. What would occur, for example, if ultrasound criteria were not used to determine the likelihood of a thyroid nodule being benign or malignant? In this circumstance, FNA/biopsy would likely always be the next step after a nodule was detected. Whereas FNA is the ‘‘gold standard’’ for nodule diagnosis, it is clearly an imperfect technique for many reasons. First, the results are non-diagnostic in approximately 15% to 20% of cases.45,46 Second, there is a false negative rate of approximately 3% to 5%.47 Third, there is wide variability in interpretative skill regarding cytopathology of the thyroid nodule. Unfortunately, in less experienced centers, the report of “follicular cells are present, cannot exclude follicular neoplasm” occurs more frequently than in centers with greater interpretive experience. This report commonly leads to the need for surgical excision. Given these considerations, it is estimated that approximately 18% of all patients who have an FNA ultimately come to surgery for nodule excision based on positive, suspicious, or non-diagnostic results, and that most of these nodules are benign.45,48,49 Of these patients who have surgery it is estimated that only 15% to 32% have cancer.45,48 Therefore, the majority of patients who come to surgery for thyroid nodule excision will have had an operation for clinically insignificant benign nodular disease.It is also important to consider a perspective on the epidemic of nodular thyroid disease as seen by ultrasound imaging and the potential cost of the FNA/biopsy workup of these nodules. For discussion purposes, assume that 1 million people of the current 293 million population of the United States undergo a thyroid ultrasound examination. Because we know that the prevalence of one or more thyroid nodules detected by high-frequency ultrasound is approximately 40%, then 400,000 people will have one or more thyroid nodules detected by ultrasound imaging. Assuming a cost of approximately $1500 for a US-guided FNA and cytologic analysis, $600 million could theoretically be spent to exclude or detect thyroid cancer in this group. Importantly, approximately 18%, or 72,000 operations could occur at a cost of nearly $20,000 each, for an additional cost of $1.44 billion. Finally, approximately 5%, or nearly 3600 operated patients could experience significant morbidity as a result of surgery including hoarseness, hypoparathyroidism, and long-lasting pain.50 Clearly, this type of aggressive management of thyroid nodules would entail massive expenditure of health care dollars and would have a potentially very negative clinical impact. The use of ultrasound screening for thyroid cancer would likely exacerbate such a scenario by significantly increasing the number of patients undergoing FNA/biopsy and unneeded surgery. In fact, the Institute of Medicine recently recommended against ultrasound screening, even for patients who may be at higher risk for thyroid cancer than the normal population—those who have been exposed to I-131 fallout from nuclear bomb testing, which occurred during 1950 to 1960.51Before ultrasound screening for thyroid cancer is implemented, its efficacy must be proven in an evidence-based manner, probably through the use of randomized controlled trials.52 Screening tests are deemed to be efficacious if four criteria are met53:1. The cancer must be fairly common.2. The new test must reveal disease earlier than the customaryway.3. The cancer must have an effective treatment.4. The value of detecting the cancer at this earlier time outweighs the risks and costs generated by screening.This fourth criterion is likely not to be met in the setting of sonographic screening for thyroid cancer. If the screening test reveals non-lethal cancers, it can cause unnecessary anxiety of the patient, and can lead to treatments that are not needed and may be costly and harmful without producing any benefit.54Historically, most papillary cancers are pa however, with the advent of high-resolution ultrasound many small cancers are now being incidentally detected. Papillary microcarcinoma is classified by the World Health Organization (WHO) as ‘‘tumors 1.0 cm or less in diameter’’.55 The prevalence of small papillary carcinomas in systematic autopsy studies where the thyroids have been sectioned semiserially has varied between 1% and 36%.56–58 This is particularly common in Scandinavian countries and in Finland, where occult papillary cancer was found in 36% of autopsies, and has been called a ‘‘normal’’ finding by some.59 These occult cancers have been found to be multifocal in 30%, and surprisingly show regional lymph node spread in 30%, and distant metastases in 1% to 3%.60 Fortunately, cervical lymph node metastasis, while common, is not life threatening in most patients. These occult papillary cancers carry a very low risk for mortality—0% in two series, and 1% in another series.11,61,62 Such data suggest that almost all occult papillary carcinomas of the thyroid remain undiscovered during life and do not contribute to mortality, with death in these individuals usually resulting from other causes unrelated to thyroid cancer. Is there value in discovering a papillary thyroid carcinoma at a smaller size or earlier stage? In the current literature on papillary thyroid cancer (PTC), by far the commonest form of endocrine malignancy, there is almost no data that convincingly prove a life-saving advantage from early diagnosis.6 Although tumor size is important in relation to prognosis in PTC,63 the recent TNM and AJCC classification,64 recognizing the unimportance of a 1-cm cut-off,65 has increased the size upper limit of a T1 tumor to 2 cm. Large studies of PTC followed for up to 60 postoperative years have demonstrated that the most significant ‘‘step-up’’ in cause-specific mortality occurs when a PTC tumor size is 4 cm or more.8,63,66 This suggests that concern about missing early or occult PTC is misplaced, and that pursuing a US-guided FNA/biopsy diagnosis in every nonpalpable thyroid nodule greater than 1 cm is likely to be impractical and most often unnecessary.67 In a recent editorial devoted to the problem of the thyroid incidentaloma, which he described as ‘‘the ignorant in pursuit of the impalpable,’’ Topliss emphasized that ‘‘screening programs for early cancers (lung, breast, prostate, and neuroblastoma) have not demonstrated a mortality difference between screened and unscreened populations despite detecting more disease at an earlier stage’’.68 In considering a US-guided FNA in a patient with solid hypoechoic lesion, Topliss concluded that ‘‘gaining informed consent should entail discussion of the uncertainties involved and it is still a rational decision to observe (and not biopsy) impalpable thyroid nodules’’.68For our practice, the ‘‘classic pattern’’ approach to the sonographic evaluation of thyroid nodules allows an effective and practical method for nodule evaluation. Using this approach, most patients with clinically significant cancers go on to appropriate further investigations, but, much more importantly, most of the patients who have benign lesions can thereby avoid a costly, and potentially harmful, further workup. Follow-up imaging in these patients (Patterns 4 through 8) is not necessary, except in the unusual circumstance when something occurs to raise new clinical concern.很多病理学条件下都可引起甲状腺结节性增大，其中包括新生物的、增生的和炎性的疾病。所有这些条件都有一系列特征表现而且可相会重叠。幸运的是，在我们的实践中，有一些特征强烈的预示病灶的潜在病理性质。甲状腺结节典型模式的评估方法，使我们可以避免不必要的和昂贵的检查，包括额外的影像检查、FNA、和外科切除。在医学上，停止进一步检查或需要进一步检查是根据前瞻性和临床判断评估的平衡。例如，乳房摄影经常诊断的乳腺良性纤维腺瘤是根据它的影像特征。没有外科切除和病理研究这些诊断是高度可能而不是绝对确定的(即影像诊断而不是确定的)。此外，前瞻性必须包括不仅要考虑癌症漏诊的成本，还要考虑没有癌肿而进行侵入性处理的成本。例如，如果超声标准无法确定甲状腺结节是良性还是恶性的，将会发生什么？在这种情况下，FNA或组织活检可能是下一步。然而，FNA是结节诊断的“金标准”，但由于很多因素，很明显它不是完美的技术。首先，近15% - 20%的病例无法做出诊断[45,46]。第二，假阴性约3% - 5%[47]。第三，对甲状腺结节的细胞病理学解释的熟练程度差异很大。不幸的是，缺乏经验的病理中心较有经验的病理中心，经常报告“存在滤泡细胞，不能完全排除滤泡细胞新生物”。这种报告通常导致外科切除。在这种情况下，估计有近18%的FNA病人最后因为是阳性的、可疑的或无诊断结果，而致结节的外科切除，但这些结节大部分是良性的[45,48,49]。在外科切除的病人中估计有15% - 32%是恶性的。因此绝大部分不至于甲状腺结节外科切除的病人，将因无关紧要的临床良性结节性疾病而进行手术。同样重要的是考虑结节性甲状腺疾病的流行性前瞻性，超声影像所见，这些结节FNA/组织活检进一步检查的潜在价值。为了讨论的目的，假定美国293百万人中的一百万人进行甲状腺超声检查。因为我们知道，高频超声探查到甲状腺一个或多个结节近40%，因此近40万人可探查到一个或多个甲状腺结节。估计一个超声引导的FNA和细胞学的分析近1500美元，在这组需要6亿的花费来排除甲状腺癌。重要的是，近18%或72000次手术发生，价值每人约2万美元，共14.4 亿美元。最终，近5%约3600例手术的病人，因手术而产生后遗症，包括声嘶、甲状旁腺功能减退和长期疼痛[50]。可澄清的是，甲状腺结节这种侵入性的处理花费巨大的卫生保健基金，而且有潜在的临床副作用。利用超声筛查甲状腺癌有可能显著增加了进行FNA/组织活检病人数量和不必要的外科手术。事实上，医学会最近推荐反对超声筛查，甚至是那些1950 &#暴露在放射性I-131核弹实验的高危人群[51]。在超声筛查甲状腺癌以前，它的效能必须被以证据为基础的方法证实，或许应用随机对照试验[52]。如果遵守四个标准，筛查试验确认是有效的[53]：1.&&癌肿必须是常见的。2.&&新的试验必须比原来更早的显示疾病。3.&&癌肿必须有有效的治疗。4.&&早期探查到癌肿的价值远大于筛查的风险和效益。这四个原则不可能与超声筛查甲状腺癌的背景一致。如果筛查试验揭示了非致死的癌症，可引起病人不必要的恐慌，导致不必要的治疗，产生费用和弊端而没有任何益处[54]。从病史上看，大部分乳头状癌当发现时可触及；然而利用现代高分辨率超声很多很小的癌肿是偶尔间发现是。世界卫生组织将乳头状微癌定义为直径&#cm的肿瘤[55]。在系统尸体解剖的研究上，甲状腺连续切面小乳头状癌的患病率差距很大，为1%和36%[56-58]。在斯堪的那维亚和芬兰特别常见，在那里尸检发现隐蔽的乳头状癌为36%，而被称为正常所见[59]。这些隐蔽的癌肿中有30%为多病灶的，并有30%已经有区域淋巴结转移，1% - 3%有远处转移[60]。幸运的是，颈部淋巴结转移非常常见，但对大部分病人来说没有生命威胁。这些隐蔽的乳头状癌死亡率的危险性极低，在两个系列研究中为0%，其它系列研究中为1％[11,61,62]。这些数据表明，几乎所有甲状腺隐蔽的乳头状癌可终生不被发现，而没有造成死亡，而在死亡的病例中，通常是由于与甲状腺癌不相关的原因而致。早期或发现小甲状腺乳头状癌是否有意义？在当前关于甲状腺乳头状癌(PTC)的文献中，内分泌恶性肿瘤最常见形成，几乎没有有说服力的数据证实早期诊断对生命有益[6]。在PTC中尽管肿瘤的大小对预后是重要的[63]，最近的美国癌期划分联合委员会的TNM分期[64]认为1cm以下的无关紧要[65]，T1期肿瘤的上限为2cm。PTC的大规模研究随访至60年显示，当使死亡率最显著增加时PTC的大小在4cm或大于4cm[8,63,66]。这些关于早期漏诊或隐蔽PTC观点是错位的，追求每个大于1cm不可触及的甲状腺结节，在超声引导下进行FNA/组织活检诊断很可能是不切实际的，而且通常是不需要的[67]。最近的评论致力于甲状腺偶发肿瘤的问题，被描述为“忽视调查不可触知的肿瘤”，Topliss强调：“早期癌症(肺癌、乳腺癌、前列腺癌和神经母细胞瘤)的筛选程序不能证实筛查和没有筛查人群死亡率的不同，尽管早期发现更多的疾病[68]。在关于病人实质低回声病灶进行超声引导FNA/组织活检方面，Topliss认为“应该获得知情同意使病人了解不确定因素，并做出合理的裁判：观察(而不是组织活检)不可触及的甲状腺结节[68]”。就我们的实践经验，超声评估甲状腺结节“典型模式”的方法是结节评估有效、可行的方法。使用这种方法，大部分临床上有明显癌症的病人可进行合理的进一步检查，但是更重要的是，大部分良性病灶的病人，因此可以避免昂贵的、有潜在危害的进一步处理。这些病人影像随访(模式4-8)是不必要的，除去罕见的情况，当一些情况发生时，引起新的临床上的关注。
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