Clinical Review & Education JAMA | Review The Diagnosis and Management of Thyroid Nodules A Review Cosimo Durante, MD, PhD; Giorgio Grani, MD; Livia Lamartina, MD; Sebastiano Filetti, MD; Susan J. Mandel, MD, MPH; David S. Cooper, MD IMPORTANCE Thyroid nodules are common, being detected in up to 65% of the general CME Quiz at jamanetwork.com/learning population. This is likely due to the increased use of diagnostic imaging for purposes unrelated to the thyroid. Most thyroid nodules are benign, clinically insignificant, and safely managed with a surveillance program. The main goal of initial and long-term follow-up is identification of the small subgroup of nodules that harbor a clinically significant cancer (≈10%), cause compressive symptoms (≈5%), or progress to functional disease (≈5%). OBSERVATIONS Thyroid function testing and ultrasonographic characteristics guide the initial management of thyroid nodules. Certain ultrasound features, such as a cystic or spongiform appearance, suggest a benign process that does not require additional testing. Suspicious sonographic patterns including solid composition, hypoechogenicity, irregular margins, and microcalcifications should prompt cytological evaluation. Additional diagnostic procedures, such as molecular testing, are indicated only in selected cases, such as indeterminate cytology (≈20%-30% of all biopsies). The initial risk estimate, derived from ultrasound and, if performed, cytology report, should determine the need for treatment and the type, frequency, and length of subsequent follow-up. Management includes simple observation, local treatments, and surgery and should be based on the estimated risk of malignancy and the presence and severity of compressive symptoms. CONCLUSIONS AND RELEVANCE Most thyroid nodules are benign. A diagnostic approach that uses ultrasound and, when indicated, fine-needle aspiration biopsy and molecular testing, facilitates a personalized, risk-based protocol that promotes high-quality care and minimizes cost and unnecessary testing. T 914 Methods PubMed and Scopus databases were searched to identify highquality studies, systematic reviews and meta-analyses, and clinical practice guidelines published in the last 3 years regarding thyroid nodule evaluation and treatment. We identified articles that focused on clinically important questions about thyroid nodule management and reviewed the reference list of the selected articles. Epidemiology With physical examination (neck palpation), thyroid nodule prevalence in iodine-sufficient populations is approximately 5%, depending on age and sex.2 However, clinicians encounter a much higher proportion of patients harboring occult thyroid nodules, reaching up to 68% of the general population.3 JAMA March 6, 2018 Volume 319, Number 9 (Reprinted) © 2018 American Medical Association. All rights reserved. Downloaded From: by a University of the Sciences User on 03/10/2018 Corresponding Author: David S. Cooper, MD, Division of Endocrinology, Diabetes, and Metabolism, 1830 E Monument St, Ste 333, Baltimore, MD 21287 (dscooper@jhmi.edu). Section Editors: Edward Livingston, MD, Deputy Editor, and Mary McGrae McDermott, MD, Senior Editor. JAMA. 2018;319(9):914-924. doi:10.1001/jama.2018.0898 hyroid nodules are defined as discrete lesions within the thyroid gland, radiologically distinct from surrounding thyroid parenchyma. 1 Their diagnosis is increasingly common in clinical practice. Among the large number of nodules found in the general population (about 16 million of individuals in the United States are estimated to have a palpable nodule; up to 219 million have an ultrasound-detectable nodule), the main goal should be the identification of nodules that are clinically relevant. These include the subgroup harboring a significant cancer (approximately 10%), and those causing (or are at risk of causing) compressive symptoms (5%), or thyroid dysfunction (5%). Approximately 90% of thyroid nodules are benign and 95% are asymptomatic and remain so during follow-up. These nodules can be safely managed with a less intensive follow-up protocol. This review provides an evidencebased summary of the optimal approach to the management of thyroid nodules. Author Affiliations: Dipartimento di Medicina Interna e Specialità Mediche, Università di Roma “Sapienza,” Roma, Italy (Durante, Grani, Lamartina, Filetti); Division of Endocrinology, Diabetes and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia (Mandel); Division of Endocrinology, Diabetes and Metabolism, The Johns Hopkins University School of Medicine, Baltimore, Maryland (Cooper). jama.com Review Clinical Review & Education Diagnosis and Management of Thyroid Nodules This discrepancy is largely due to incidental discovery of asymptomatic nodules, generally small, due to the increased use of diagnostic imaging for purposes unrelated to the thyroid (the so-called thyroid incidentaloma). The reported prevalence is about 65% with ultrasonography, 15% with computed tomography (CT) or magnetic resonance imaging (MRI), and 1% to 2% with 18fluorodeoxyglucose positron emission tomography (PET).4 Nodules are solitary in about the half of the patients.5 The prevalence of thyroid nodules and the rate of multinodularity increase with age,6 female sex, and body mass index.3 Approximately 10% of patients who present with thyroid nodules are at risk of malignancy,7 the rate of which ranges from between 5% and 13% of patients with ultrasound-, CT-, or MRIdetected incidentalomas. In case of focal uptake on the PET scan and an increased maximum standardized uptake value, the risk of malignancy may increase to 55%.8 Risk factors for malignancy include childhood irradiation (mainly head and neck and whole body radiation),9,10 exposure to ionizing radiation from fallout in childhood or adolescence,11 family history of thyroid cancer or hereditary syndromes that include thyroid cancer (eg, multiple endocrine neoplasia syndrome type 2, familial adenomatous polyposis), rapid nodule growth, or hoarseness. 1 Insufficient evidence is available for other factors proposed to be associated with nodule formation or malignancy, such as serum levels of thyrotropin,12 thyroid autoantibodies,13 obesity,14 and metabolic syndrome.15 The US Preventive Services Task Force (USPSTF), which reviews the effectiveness of screening programs in asymptomatic individuals, recommended against screening for thyroid cancer in adults without signs or symptoms of the disease.16 The panel concluded that the potential harms likely outweigh any potential benefits. The USPSTF recommendation does not apply to patients with risk factors.16 Screening individuals with previous neck irradiation or familial nonmedullary thyroid cancer (family with !3 affected relatives, or genetic syndromes such as Cowden disease, familial adenomatous polyposis, Carney complex) may lead to an earlier diagnosis of cancer, but there is insufficient evidence that this would reduce morbidity or mortality.1 For this reason, there is no evidence to support ultrasound screening in these contexts. Genetic counseling and testing for rearranging during transfection (RET) germline mutations should be offered to firstdegree relatives of patients with proven hereditary medullary thyroid cancer.17 Box. Differential Diagnoses of Anterior Neck Masses Congenital conditions (lateral neck: brachial anomalies, cystic hygroma; central neck: thyroglossal duct cysts) Inflammatory/infectious diseases (lymphadenopathy, sialadenitis, neck abscess, tuberculosis, cat-scratch disease [Bartonella lymphadenitis]) Trauma Thyroid nodule Malignancy located in the left lobe with posterior extension, such that it may cause extrinsic compression of the cervical esophagus.19 Physical examination of the thyroid should include inspection for visible lumps and palpation of the thyroid and cervical lymph nodes, searching for firm or fixed nodes or a tender mass. The differential diagnosis of a palpable anterior neck mass is summarized in Box.20,21 Firm, fixed, matted, or rapidly growing masses require prompt evaluation.20 Physical examination is frequently normal because many thyroid nodules are not palpable because of their small size, posterior location within the gland, or a consistency similar to the thyroid gland.22 Laboratory Testing Thyrotropin and Thyroid Hormones Serum thyrotropin should be measured during the initial evaluation of all patients with a thyroid nodule.1 The goal is to exclude the small number of hyperfunctioning nodules ("5% of all nodules)23: if the serum thyrotropin is subnormal, free thyroxine plus total or free triiodothyronine should be measured22 and a radionuclide scan performed, looking for focal uptake.1,22 If the serum thyrotropin level is higher than the reference range, the free thyroxine and antithyroid peroxidase antibody should be measured to quantify the degree of thyroid hypofunction and to evaluate for autoimmune (Hashimoto) thyroiditis.22 Thyroglobulin Routine measurement of serum thyroglobulin in evaluation of nodules is not recommended.1 Even if some evidence suggests that very high thyroglobulin levels may predict malignancy,24 thyroglobulin can also be elevated in many benign thyroid diseases (eg, multinodular goiter, thyroiditis). Therefore, this test has inadequate specificity for thyroid cancer diagnosis. Clinical Evaluation Most patients are asymptomatic. Symptoms from a thyroid nodule or thyroid enlargement include: globus sensation (sensation of a lump or foreign body in the throat); dysphagia or swallowing complaints (stasis, choking, odynophagia); dyspnea; dysphonia or hoarseness; and pain (due to acute increase of nodule size, as in case of bleeding into the nodule). The presence of symptoms from a thyroid nodule depends on its size and location. In particular, a globus sensation is more likely to be associated with a nodule size of more than 3 cm and a position close to the trachea (isthmic nodules more than paraisthmic nodules).18 Swallowing complaints are reported in 67% of the patients with either hypothyroidism or thyroid nodules. However, if attributable to nodular thyroid disease, the lesion is typically Calcitonin Calcitonin is produced by the parafollicular C cells of the thyroid and is a serum marker for medullary thyroid cancer. Recent guidelines included no recommendation regarding the measurement of serum calcitonin to evaluate thyroid nodules.1 Although routine calcitonin evaluation may detect medullary thyroid cancer at an earlier stage, there is insufficient evidence that early diagnosis reduces medullary thyroid cancer–specific mortality.1 Furthermore, assay performance, specificity and cost-effectiveness are suboptimal.25 If measured, basal calcitonin levels of more than 100 pg/mL suggest a diagnosis of medullary thyroid cancer (sensitivity, 60%; specificity, 100%).26(To convert calcitonin from pg/mL to pmol/L, multiply by 0.292.) (Reprinted) JAMA March 6, 2018 Volume 319, Number 9 jama.com © 2018 American Medical Association. All rights reserved. Downloaded From: by a University of the Sciences User on 03/10/2018 915 916 Downloaded From: by a University of the Sciences User on 03/10/2018 Intermediate-risk definition Risk of malignancy, 5%-15% FNAB >20 mm Sonographic pattern Slightly hypoechoic (vs thyroid tissue) or isoechoic nodules, with ovoid-to-round shape, smooth or ill-defined margins May be present Intranodular vascularization Elevated stiffness at elastography Macro or continuous rim calcifications Indeterminate hyperechoic spots Intermediate or Moderately Suspicious Thyroid Nodules Low-risk definition Risk of malignancy, 1% FNAB >20 mm (selective)a Sonographic pattern Cysts (fluid component >80%) Mostly cystic nodules with reverberating artifacts and not associated with suspicious ultrasound signs Isoechoic spongiform nodules, either confluent or with regular halo Low-Risk and Benign Thyroid Nodules AACE, ACE, and AME, 201622 Intermediate-suspicion definition Risk of malignancy, 10%-20% FNAB ≥10 mm Sonographic pattern Hypoechoic solid nodule with smooth margins without microcalcifications, extrathyroidal extension or taller than wide shape Intermediate-risk (EU-TIRADS 4) definition Risk of malignancy, 6%-17% FNAB >15 mm Sonographic pattern Oval shape, smooth margins, mildly hypoechoic, without any feature of high risk Low-risk (EU-TIRADS 3) risk definition Risk of malignancy, 2%-4% FNAB >20 mm Sonographic pattern Oval shape, smooth margins, isoechoic or hyperechoic, without any feature of high risk Very low–suspicion risk definition Risk of malignancy, <3% FNAB ≥20 mm or observation Sonographic pattern Spongiform/partially cystic nodules without any ultrasound features defining low-, intermediate-, or high-suspicion patterns Low suspicion–risk definitions Risk of malignancy, 5%-10% FNAB ≥15 mm Sonographic pattern Isoechoic/hyperechoic solid or partially cystic nodule with eccentric solid area without microcalcifications, irregular margin, extrathyroidal extension, taller than wide shape Benign (EU-TIRADS 2) definition Risk of malignancy, ≈0% FNAB is not indicated Sonographic pattern Pure, anechoic cysts; Entirely spongiform nodules EU-TIRADS, 201731 Benign definition Risk of malignancy, <1% FNAB is not indicated Sonographic pattern Purely cystic nodules (no solid component) ATA, 20151 Moderately suspicious (TR4) definition Risk of malignancy, 5%-20% FNAB >15 mm Sonographic patterns Hypoechoic solid noncalcified nodules with oval shape and either smooth or irregular or lobulated margins Isoechoic solid or mixed noncalcified nodules with either nonparallel orientation (taller than wide), lobulated or irregular margins, or punctate echogenic foci Mildly suspicious (TR3) risk definition Risk of malignancy, 5% FNAB ≥25 mm Sonographic pattern Isoechoic solid or hypoechoic cystic noncalcified nodules with smooth margins and oval shape Not suspicious (TR2) definition Risk of malignancy, 2% FNAB is not indicated Sonographic pattern Mixed cystic/solid noncalcified nodules with smooth margins and oval shape Benign (TR1) definition Risk of malignancy, 2% FNAB is not indicated Sonographic pattern Spongiform Pure cyst ACR TIRADS, 201730 Table 1. Standardized Sonographic Scoring Systems Proposed or Endorsed by Practice Guidelines for Risk-Based Fine-Needle Aspiration Biopsy Guidance for Thyroid Nodules (continued) Clinical Review & Education Review Diagnosis and Management of Thyroid Nodules JAMA March 6, 2018 Volume 319, Number 9 (Reprinted) © 2018 American Medical Association. All rights reserved. jama.com Review Clinical Review & Education An FNAB is recommended for smaller nodules that are subcapsular location near the recurrent nerve or trachea; suspicious lymph nodes or extrathyroid spread; personal or family history of thyroid cancer; history of head and neck irradiation; coexistent suspicious clinical findings. An FNAB indicates the size above which a FNAB cytology is recommended. c Growing nodule, high-risk history, before surgery or local therapies. In accordance with the presence of 1 or more suspicious findings. b a High-suspicion definiton Risk of malignancy, >70%-90% FNAB ≥10 mm Sonographic pattern Solid hypoechoic nodule or solid hypoechoic component of partially cystic nodule with ≥1 of the following: Irregular margins (infiltrative, microlobulated) Microcalcifications Taller than wide shape Rim calcifications with small extrusive soft tissue Extrathyroidal extension High-risk definition Risk of malignancy, 50%-90%b FNAB ≥10 mm (5 mm, selective)c Sonographic patterns Nodules with ≥ 1 of the following: Marked hypoechogenicity (vs prethyroid muscles) Spiculated or lobulated margins Microcalcifications Taller-than-wide shape Extrathyroidal growth Pathologic adenopathy Abbreviations. AACE/ACE/AME, American Association of Clinical Endocrinologists, American College of Endocrinology, and Associazione Medici Endocrinologi; ACR, American College of Radiologists; ATA, American Thyroid Association; EU-TIRADS, European Thyroid Imaging Reporting and Data System; FNAB, fine-needle aspiration biopsy; TR, American College of Radiologists Thyroid Imaging Reporting and Data System. Suspicious (TR5) definition Risk of malignancy, ≥20% FNAB >10 mm Sonographic pattern Hypoechoic solid nodule with any of the following Nonparallel orientation (taller than wide) Extrathyroidal extension Punctate echogenic foci Isoechoic solid nodule with irregular or lobulated margins and either peripheral rim calcifications or punctate echogenic foci High-risk (EU-TIRADS 5) definition Risk of malignancy, 26%-87% FNAB >10 mm Sonographic pattern Nodules with ≥ 1 of the following: Nonoval shape Irregular margins Microcalcifications Marked hypoechogenicity ACR TIRADS, 201730 EU-TIRADS, 201731 ATA, 20151 High-Risk or Suspicious Thyroid Nodules AACE, ACE, and AME, 201622 Table 1. Standardized Sonographic Scoring Systems Proposed or Endorsed by Practice Guidelines for Risk-Based Fine-Needle Aspiration Biopsy Guidance for Thyroid Nodules (continued) Diagnosis and Management of Thyroid Nodules Ultrasound, Cytology, and Molecular Testing Thyroid Ultrasonography Sonography is the primary tool used for initial cancer risk stratification of thyroid nodules and subsequently deciding whether to order a fine-needle aspiration biopsy. Because the thyroid is superficially located in the neck, with its posterior border generally situated less than 4 cm from the skin, high-resolution (!12 MHz) probes provide excellent image definition. Ultrasound is indicated when either the thyroid gland is palpably abnormal or a thyroid nodule is incidentally detected on another radiological study. Nonspecific symptoms or abnormal laboratory test results (such as fatigue, increased serum thyrotropin levels, or autoimmune thyroiditis) are not indications for sonography. However, ultrasound is necessary to differentiate between asymmetric involvement of the thyroid gland by lymphocytic thyroiditis vs a superimposed thyroid nodule, for which further evaluation may be required. A diagnostic ultrasound report should include description of the background thyroid parenchyma, nodule location, size (in 3 dimensions), sonographic features (Table 1), and survey of the cervical lymph nodes.27 Certain sonographic characteristics are associated with thyroid cancer while others are more likely to indicate a benign nature. Ultrasound characteristics associated with malignancy include solid composition, hypoechogenicity (nodule is darker than normal thyroid tissue), margins that appear infiltrative or irregular, and presence of microcalcifications. In addition, a nodule surrounded by interrupted rim calcifications with evidence of soft tissue extrusion is likely to be an infiltrative cancer.28 Conversely, pure cysts and nodules with a “spongiform” consistency, defined when more than half of nodule volume is composed of microcystic spaces, are unlikely to be malignant (<2%). Cancer risk is low (<5%-10%) for solid noncalcified smoothly marginated nodules that are either isoechoic or hyperechoic (same or lighter gray scale imaging compared with normal thyroid).29 The American Thyroid Association1 and other professional groups22,30-32 have devised similar but not identically tiered systems to classify nodules by constellations of sonographic features that convey cancer risk and to recommend size cutoffs for fineneedle aspiration biopsy (Table 1, Figure 1, and Figure 2). Guidelines from endocrinology societies have focused on nodule pattern identification,1,22,31 accompanied by figures illustrating these patterns. Guidelines correlate each pattern to an estimated cancer risk. Recently, the American College of Radiology30 recommended a point system for systematic assessment of imaging for thyroid nodules (Thyroid Imaging Reporting and Data System); this mirrors the American College of Radiology approach to imaging other organs (eg, the breast). Points are assigned based on 5 ultrasound features and the sum determines the Thyroid Imaging Reporting and Data System classification of the nodule, its estimated cancer risk, and recommendations for either fine-needle aspiration biopsy or surveillance. Malignancy risk estimates based on sonographic appearance are similar across all 4 classification systems; however, fineneedle aspiration biopsy recommended cutoff sizes differ (Table 1, Figure 1, and Figure 2). Fine-needle aspiration biopsy is not recommended for pure cysts, unless it is for fluid aspiration for symptomatic relief. If fineneedle aspiration biopsy is to be performed for spongiform nodules, the size cutoff is larger than 2 cm, with some guidelines not (Reprinted) JAMA March 6, 2018 Volume 319, Number 9 jama.com © 2018 American Medical Association. All rights reserved. Downloaded From: by a University of the Sciences User on 03/10/2018 917 Clinical Review & Education Review Diagnosis and Management of Thyroid Nodules Figure 1. Ultrasonographic Features of Thyroid Nodules Suspicious for Malignancy A B C D E F A, Markedly hypoechoic nodule (similar echogenicity as the surrounding strap muscles) with irregular margins. B, Taller-than-wide hypoechoic nodule. C, Markedly hypoechoic nodule with regular margins. D, Hypoechoic nodule with infiltrative margins and suspicious extrathyroidal extension (indicated by a blue arrowhead). E, Multiple interruptions in calcific rim with evidence of extrusive tissue (indicated by blue arrowheads). Echogenicity is difficult to interpret because of acoustic shadowing of the calcific rim). F, hypoechoic solid nodule with microcalcifications and irregular margins. The yellow arrowheads indicate the thyroid nodule in each panel. The gray scale graphically represents the shades of gray that can be provided by the ultrasound equipment. recommending fine-needle aspiration biopsy.30,31 There is wide variability in the description of single ultrasonographic features (Cohen κ range, 0.4-0.6 for most variables); the classification systems may improve interobserver agreement (κ range, 0.61-0.82).33 No evidence is available to guide which system is best. Long-term prospective studies are needed. about 20% to 30% of all biopsies, are indeterminate readings and usually require additional evaluation, having a risk of malignancy of 10% to 30% and 25% to 40%, respectively.34 In the United States, the most common approach is the avoidance of surgery because the majority of nodules in these 2 categories are benign,42,45 and, when cancer is identified, it is usually nonaggressive. In fact, these indeterminate categories rarely include aggressive variants of papillary thyroid cancer because more than 90% are reported in categories 5 and 6,46 and the rate of follicular thyroid cancer is low (≈20% of malignant cases).47 The new Bethesda system adjusts the risk of malignancy of the indeterminate diagnostic categories and their management recommendations due to the recent recognition of the noninvasive follicular thyroid neoplasm with papillar y-like nuclear feature s (NIFTP).34,48 This is thought to represent an early stage of invasive encapsulated follicular variant of papillary cancer, with an extremely low malignant potential. 49 However, surgery is required for a definitive diagnosis, and initial management is similar to that used for a low-risk thyroid cancer.50 Cytology Fine-needle aspiration biopsy provides the most definitive diagnostic information for evaluating thyroid nodules.1 Fine-needle aspiration biopsy is simple, safe, and reliable. If the nodule is not easily palpable or cystic, fine-needle aspiration biopsy is best performed under ultrasound guidance. In the United States and much of the world, thyroid cytological results reporting is stratified using the 2017 updated Bethesda classification system, 34 which provides 6 diagnostic categories (Table 2).35-44 Category 1 is defined as nondiagnostic or insufficient; category 2, benign, and categories 5 and 6, suspicious for malignancy and malignant, respectively. Despite interobserver differences in cytological interpretation,34 Bethesda categories 2, 5, and 6 provide high enough negative (96.3%, category 2) and positive predictive values (75.2%, category 5; 98.6%, category 6) for accurate clinical decision making. 42 However, categories 3 and 4, comprising 918 Molecular Testing Molecular testing of fine-needle aspiration biopsy specimens has gained acceptance in the United States as a popular51 and poten- JAMA March 6, 2018 Volume 319, Number 9 (Reprinted) © 2018 American Medical Association. All rights reserved. Downloaded From: by a University of the Sciences User on 03/10/2018 jama.com Review Clinical Review & Education Diagnosis and Management of Thyroid Nodules Figure 2. Imaging Features of Indeterminate and Low Suspicion Thyroid Nodules Imaging features of indeterminate thyroid nodules A B C Ultrasonographic features of low or very low suspicion thyroid nodules D E F A, Elevated stiffness at elastography (red indicates soft tissues; blue, hard tissues; and green, intermediate values of stiffness). B, Complete rim calcification. C, Slightly hypoechoic nodule with intranodular vascularization. Flow velocity is converted into a color scale. Flow toward the transducer is represented in red; away from the transducer is depicted in blue. D, pure cyst. E, Spongiform nodule with more than 50% of the nodule volume composed of microcystic spaces. F, solid hyperechoic nodule. The arrowheads indicate the thyroid nodule in each panel. The gray scale graphically represents the shades of gray that can be provided by the ultrasound equipment. tially practice-changing approach52,53 to diagnosing indeterminate thyroid nodules. Mutations occur principally in genes coding for proteins in the mitogen-activated protein kinase (MAPK or MAP kinase) pathway that regulates cellular proliferation and differentiation. A mutation in the BRAF gene (V600E) is found in approximately 40% of papillary thyroid cancers, as well as in some poorly differentiated (33%) and anaplastic cancers (45%) that likely arise from papillary cancers.54 Mutations in the RAS gene family are found in some papillary cancers (13%, generally the encapsulated follicular variant), follicular thyroid cancers (40%-50%), benign follicular adenomas (20%-40%),54 as well as in NIFTP (30%).49 Fusion genes, hybrid genes formed from 2 previously separate genes—in which the RET gene that codes for a cell surface receptor protein not normally expressed by thyroid follicular cells is fused with a second unrelated gene, called a RET/PTC oncogene—has been associated with radiation-related papillary thyroid cancers. Another fusion gene between the gene coding for the thyroid transcription factor PAX8 and the peroxisome proliferator-activated receptor, gamma isoform (PPARG) gene (PAX8/PPARG) is seen in some follicular thyroid cancers (30%-35%), the follicular variant of papillary thyroid cancer (38%), and in some follicular adenomas (2%-13%). Mutations in the telomerase reverse transcriptase (TERT) and TP53 tumor suppressor genes have also been observed in some thyroid cancers. In particular, TERT has been reported in less than 10% of papillary thyroid cancer and more than 70% of anaplastic thyroid cancer; TP53, in less than 1% of papillary thyroid cancer and more than 70% of anaplastic thyroid cancer.53 The 2 most common molecular testing strategies are mutational analysis and gene expression analysis, in which genetic information can be derived from the same material obtained in the original fine-needle aspiration biopsy sample. Mutational analysis involves isolating DNA from thyroid follicular cells in the specimen and performing gene sequencing, focusing on possible mutations in BRAF, RAS, TERT, TP53, and other relevant genes, as well for the presence of fusion genes.55 Such mutational testing has been termed a rule in test because if a BRAF, TERT, or TP53 mutation is found or if a fusion gene is detected, thyroid cancer is almost always present.56 However, while mutations in RAS genes (HRAS, KRAS, NRAS) are present in thyroid cancers, they are also present in (Reprinted) JAMA March 6, 2018 Volume 319, Number 9 jama.com © 2018 American Medical Association. All rights reserved. Downloaded From: by a University of the Sciences User on 03/10/2018 919 Clinical Review & Education Review Diagnosis and Management of Thyroid Nodules Table 2. The Bethesda System for Reporting Thyroid Cytopathology: Implied Risk of Malignancy and Recommended Clinical Management Diagnostic Category Risk of Malignancy, % Usual Managementa Category 1: Nondiagnostic or Unsatisfactory Cyst fluid only Virtually acellular specimen Obscuring blood, artifacts 0-5b Repeat FNAB with ultrasound guidance 0-3c Clinical and sonographic follow-upc Category 2: Benign Benign follicular nodule (eg, adenomatoid nodule, colloid nodule) Chronic lymphocytic (Hashimoto) thyroiditis Granulomatous (subacute) thyroiditis Category 3: Atypia of Undetermined significance or Follicular Lesion of Undetermined Significance ≈10-30d Focal nuclear atypia Predominance of Hurthle cells Microfollicular pattern in a hypocellular specimen Repeat FNAB, molecular testing, or lobectomy Category 4: Follicular Neoplasm or Suspicious for a Follicular Neoplasmf Crowded and overlapping follicular cells some or most of which are arranged as microfollicles 25-40e Molecular testing, lobectomy 50-75 Near total thyroidectomy or lobectomyg,h 97-99 Near total thyroidectomyh,i Category 5: Suspicious for Malignancy Suspicious for papillary thyroid carcinoma Suspicious for medullary thyroid carcinoma Suspicious for metastatic carcinoma Suspicious for lymphoma Category 6: Malignant Papillary thyroid carcinoma Poorly differentiated carcinoma Medullary thyroid carcinoma Undifferentiated (anaplastic) carcinoma Squamous cell carcinoma Carcinoma with mixed features (to be described) Abbreviation: FNAB, fine-needle aspiration biopsy. a Actual management may depend on other factors (eg, clinical, sonographic) besides the FNA interpretation. b The risk of malignancy varies with the type or structure of the nodule (ie, solid vs complex vs !50% cystic). Nondiagnostic aspirates from solid nodules are associated with a higher risk of malignancy vs those showing cystic change of 50% or more and low-risk ultrasonographic features. c Estimate extrapolated from studies showing correlation between biopsied nodule and surgical pathology follow-up.35-38 See Figure 3 for suggested timing. d Estimates extrapolated from histopathologic data from large case cohorts (including repeat atypical FNAs) and meta-analysis of the post-2007 literature.35,39-42 nonmalignant thyroid neoplasms and in NIFTP, and are therefore less specific. Furthermore, if no mutations are found, a thyroid malignancy with a mutation that was not assessed could still be present (≈ 4%); therefore, mutational testing may lead to both false-negative and false-positive results, especially if RAS mutations are found. In a single-institution study involving 239 patients with Bethesda category 3 or 4 cytology, the mutational testing strategy (ThyroSeq v2) yielded a negative predictive value when a mutation was not found of about 96% and a positive predictive value of approximately 80%.57 In a second single-institution study involving 182 patients with 190 Bethesda category 3 and 4 cytologies, the negative predictive value was 91% (95% CI, 82%-97%) and the positive predictive value was 42% (95% CI, 25%-61%).58 BRAF- and RAS-mutation status may provide information beyond diagnosis: BRAF-positive malignant nodules are frequently present in malignant or suspicious Bethesda cytology categories and frequently show suspicious sonographic and advanced histological features, while RAS-positive malignancies are more dif920 e Estimates extrapolated from histopathologic data from large case cohorts and meta-analysis of the post-2007 literature.35,39-44 f Includes cases of follicular neoplasm with oncocytic features (Hürthle cell neoplasm). g Some studies have recommended molecular analysis to assess the type of surgical procedure (lobectomy vs total thyroidectomy). h In the case of “suspicious for metastatic tumor” or a malignant interpretation indicating metastatic tumor rather than a primary thyroid malignancy, surgery may not be indicated. i Lobectomy is appropriate for most papillary thyroid cancers smaller than 4 cm, without other features such as gross extrathyroidal extension or clinical or radiological lymphadenopathy. ficult to identify by sonography, more commonly reported in lowerrisk, indeterminate cytology categories, and usually have an indolent behavior.59 The second type of molecular testing, gene expression analysis or gene expression classifier (GEC), uses a proprietary algorithm to analyze the expression of specific genes in a 142-gene panel. Nodules are classified as benign or suspicious rather than as malignant. The test is designed to identify nodules that do not require surgery. In the original multi-institutional validation study, a benign Afirma test had a negative predictive value of approximately 95%.60 In a pooled analysis of 12 studies involving 1303 nodules, the negative predictive value was 92% (95% CI, 87%96%) and the malignanc y prevalence of 31% (95% CI, 29%-34%).61 The GEC has a low positive predictive value (range, 13%-23%) in the context of a suspicious GEC result when NIFTP is factored in.62 MicroRNA analysis is a more recent method for molecular testing for which there are limited data 63 but may prove to be useful in diagnostic decision making. Future refinement in molecular testing strategies is expected, with improved diagnostic performance. JAMA March 6, 2018 Volume 319, Number 9 (Reprinted) © 2018 American Medical Association. All rights reserved. Downloaded From: by a University of the Sciences User on 03/10/2018 jama.com Review Clinical Review & Education Diagnosis and Management of Thyroid Nodules Figure 3. Algorithm for the Follow-up of Cytologically Benign Thyroid Nodules or Nodules Without Indication for Fine-Needle Aspiration Cytology Patient with suspected thyroid nodule FNAB indicated (see Table 1) Perform thyroid ultrasound FNAB not indicated (see Table 1) Nodule without FNAB assessment Cytologically benign nodule (Bethesda class 2) High suspicion sonographic pattern Intermediate to very low suspicion sonographic pattern High suspicion sonographic pattern (nodule size < 1 cm)a Repeat FNAB within 12 mo Repeat thyroid ultrasound Intermediate to low estimated malignancy risk: within 12-24 mo Very low estimated malignancy risk: after 24 mo, if ever Repeat thyroid ultrasound after 6-12 mo No change Intermediate to low suspicion sonographic pattern Very low suspicion sonographic pattern Repeat thyroid ultrasound after 12-24 mo Repeat thyroid ultrasound after 24 mo, if everb Nodule growthc New suspicious sonographic features Perform FNAB Repeat thyroid ultrasound High estimated malignancy risk: within 6-12 mo Intermediate to low estimated malignancy risk: within 12-24 mo Very low estimated malignancy risk: after 24 mo, if ever 2 Benign (Bethesda class 2) cytology results Nondiagnostic (Bethesda class 1) cytology results Indeterminate or malignant (Bethesda classes 3, 4, 5, 6) cytology results No further FNAB assessment Repeat thyroid ultrasound for growth surveillance only Repeat FNAB (see Table 2) Manage based on risk of malignancy (see Table 2) Sonographic suspicion in this Figure is graded according to the American Thyroid Association Guidelines. FNAB indicates fine-needle aspiration biopsy. a Subcentimeter thyroid nodules harboring high-suspicion sonographic features and not requiring routine biopsy include those nodules without evidence of extrathyroidal extension or sonographically suspicious lymph nodes. Subcapsular location near the recurrent nerve or trachea, patient age (<40 years old being at higher risk) and preference, a strong family history of thyroid cancer or known syndromes associated with thyroid cancer, or a history of therapeutic head and neck or whole body radiation exposure as children may drive decision making toward performing an FNAB. Molecular testing is expensive, costing from between $3000 and $5000 per test in 2015, depending on the specific testing strategy.64 Several studies suggested that molecular testing using the GEC is cost-effective,65-67 primarily because of a decrease in the number of diagnostic surgeries and their associated complications when the test results are negative. However, most of these analyses are based on simulation modeling rather than on actual patient data, and the results vary depending on the test performance parameters, malignancy rates in the patient population, anticipated surgical procedure, surgical complication rates, health care setting, and other factors.56 Molecular testing results in a decrease in number of diagnostic surgeries in the United States, which benefits the patient, but the high cost of testing makes it unaffordable in many parts of the world. b Nodules smaller than 1 cm with a very low-suspicion pattern do not require routine sonographic follow-up, while such nodules larger than 1 cm should be followed up at more than 24 months intervals, if ever. c The minimal clinically significant change in nodule size should be a 20% increase in at least 2 diameters with a minimum increase of 2 mm, which corresponds to an increase in nodule volume of more than 50%. Compared with a slower growth rate, nodule growth of more than 2 mm a year vs slower growth rate predicts malignancy (relative risk, 2.5; 95% CI, 1.6-3.1; P < .001).71 If compressive symptoms appear following thyroid nodule growth, consider surgery. Management of Thyroid Nodules Nonoperative Management of Benign Thyroid Nodules More than 90% of detected thyroid nodules are clinically insignificant because they have no ultrasound features that suggest malignancy or because they are cytologically benign.68 In one series of 2000 consecutive nodules that were at least 1 cm, 58% were sonographically benign or of low suspicion.69 The rate of cytologically benign nodules ranges from 39% to 73% in large series.42 In a 5-year prospective study involving 992 patients with 1597 apparently benign thyroid nodules on the basis of sonographic appearance and cytology, most (≈85%) did not grow at all.5 Those that grew exhibited a slow and steady growth, with a mean 5-year largest diameter increase of about 5 mm. After multivariable logistic regression analysis, nodule growth was associ(Reprinted) JAMA March 6, 2018 Volume 319, Number 9 jama.com © 2018 American Medical Association. All rights reserved. Downloaded From: by a University of the Sciences User on 03/10/2018 921 Clinical Review & Education Review Diagnosis and Management of Thyroid Nodules ated with the presence of multiple, larger nodules, and younger age. Most important, very few (0.3%) of the nodules included in the study were found to be cancerous during the 5-year period. Furthermore, malignancy was predicted by a change in the sonographic characteristics of the nodule, not growth. The risk of malignancy based on the sonographic pattern should guide not only the initial indication for fine-needle aspiration biopsy, but also the type, frequency, and the need for follow up. An algorithm, based on the authors’ experience, is shown in Figure 3. The rate of false-negative results in thyroid biopsy cytology is very low (<3%).5,70 However, cytologically benign thyroid nodules with highly suspicious ultrasound features warrant a repeat biopsy within 12 months.1,22 In this subset of nodules the risk of falsenegative cytological results is higher: in a series of 1343 cytologically benign nodules, Kwak et al70 reported a 20% malignancy rate in nodules with suspicious sonographic features vs 0.6% in nodules that were benign based on both cytology and sonography. For nodules that are benign based on sonographic and cytological results, evaluation, if performed, should be at least 24 months later, as an earlier ultrasound is unlikely to be informative. According to the current guidelines, sonographic surveillance of low- to intermediate-risk nodules should be done after 12 to 24 months,1 despite some data suggesting that this interval could be safely extended.36 In this case, repeat biopsy should be considered in case of nodule growth or the development of suspicious ultrasound features.1,22,30 The minimal clinically significant change in nodule size should be a 20% increase in at least 2 diameters with a minimum increase of 2 mm, corresponding to an increase in nodule volume of more than 50%.1 After 2 benign cytology results, the risk of malignancy is virtually zero, irrespective of the sonographic appearance.70 For these patients, continued follow-up may be discontinued, and a surveillance strategy aimed at nodule growth assessment may be warranted only for larger nodules that could more easily lead to compressive symptoms.1,22 In the case of thyroid nodules that do not meet the fine-needle aspiration biopsy criteria because of their sonographic pattern or size (see the previous section), sonographic reassessments should be performed after 6 to 12 months for high risk nodules, 12 to 24 months for low- to intermediate-risk nodules, and at least 24 months (if ever) for very low-risk nodules larger than 1 cm. 1 These long-term follow-up recommendations are mainly based on low-quality evidence or expert opinion. A study directly comparing the growth rate of benign and malignant thyroid nodules showed that the latter were more likely to grow more than 2 mm per year (relative risk, 2.5): this clinical parameter can contribute to the assessment of thyroid cancer risk, particularly in nodules not submitted to cytology.71 Thyrotropin-suppressive therapy with thyroid hormone is not recommended.1,22 ARTICLE INFORMATION Accepted for Publication: January 30, 2018. Author Contributions: Dr Durante had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Concept and design: Durante, Filetti, Mandel, Cooper. 922 Surgical Management of Thyroid Nodules Thyroid lobectomy provides histological diagnosis and tumor removal with a lower risk of complications. The risks of total thyroidectomy include recurrent laryngeal nerve injury (2.5% of the procedures, rarely bilateral), hypocalcemia (8.1%), and hemorrhage.72 However, in some situations subsequent surgery for completion thyroidectomy (ie, the removal of the remnant thyroid tissue) will be required after lobectomy.1 The presence of large bilateral thyroid nodules1,73 or other thyroid conditions such as Graves disease73 favors total thyroidectomy. Patients with cytologically suspicious or malignant nodules (ie, Bethesda classes 5 and 6) should generally be referred for surgery. Small (<1 cm) intrathyroidal cancers could undergo active ultrasound surveillance without surgery. 1,74 In patients with smaller (< 4 cm) Bethesda Class 5 or 6 tumors, lobectomy or total thyroidectomy are both acceptable approaches, while for patients with large ones (> 4 cm), clinical or radiologic evidence of gross extrathyroidal extension,1 clinical or radiologic evidence of lymph node or distant metastases, or both, the preferred surgical approach is total thyroidectomy. When surgery is considered for indeterminate nodules (ie, Bethesda classes 3 and 4) lobectomy is preferred.1,73 A bilateral procedure could be considered for those patients in which completion thyroidectomy would be recommended in order to administer radioiodine should the nodule prove to be malignant histologically.1 When clinical, cytological, or sonographic findings are discordant, a multidisciplinary team approach is recommended.73 Surgery for large (> 4 cm) cytologically benign nodules should be considered if malignancy is considered possible, in the setting of new suspicious sonographic features (despite cytological findings),1,22 or compressive symptoms. Alternative Treatments Recently, image-guided minimally invasive techniques (percutaneous ethanol ablation, radiofrequency, laser, microwave ablation, and high-intensity focused ultrasound) have been proposed and may be considered for treating clinically relevant benign thyroid nodules.22,75 Radioiodine therapy should be considered for patients with hyperfunctioning nodules whose biochemical testing shows hyperthyroidism, but surgery is also a reasonable approach in patients with large (> 4 cm) nodules.22 Conclusions Most thyroid nodules are benign. A diagnostic approach that uses ultrasound and, when indicated, fine-needle aspiration biopsy and molecular testing, facilitates a personalized, risk-based protocol that promotes high-quality care and minimizes cost and unnecessary testing. Acquisition, analysis, or interpretation of data: Grani, Lamartina, Filetti, Mandel, Cooper. Drafting of the manuscript: Durante, Grani, Lamartina, Mandel, Cooper. Critical revision of the manuscript for important intellectual content: All authors. Administrative, technical, or material support: Lamartina, Cooper. Supervision: Durante, Filetti, Mandel, Cooper. Funding/Support: Drs Grani and Lamartina contributed to this article as recipients of the PhD program of Biotechnologies and Clinical Medicine of the University of Rome, Sapienza. Dr Cooper contributed to this article as the recipient of the Visiting Professor for Research Activities 2016 grant at University of Rome, Sapienza (C26V157CMC). Role of the Funder/Sponsor: The Sapienza University of Rome had no role in the design and JAMA March 6, 2018 Volume 319, Number 9 (Reprinted) © 2018 American Medical Association. All rights reserved. Downloaded From: by a University of the Sciences User on 03/10/2018 jama.com Review Clinical Review & Education Diagnosis and Management of Thyroid Nodules conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication. Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported. Submissions: We encourage authors to submit papers for consideration as a Review. Please contact Edward Livingston, MD, at Edward .livingston@jamanetwork.org or Mary McGrae McDermott, MD, at mdm608@northwestern.edu. REFERENCES 1. Haugen BR, Alexander EK, Bible KC, et al. 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer. Thyroid. 2016; 26(1):1-133. 2. Mazzaferri EL. 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