Subcategorization of atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS): a study applying Thyroid Imaging Reporting and Data System (TIRADS)

Effects of Implementation of European Thyroid Imaging Reporting and Data System Risk Stratification in a Thyroid Cancer Program in Western Sweden: A Retrospective Cohort Study

OBJECTIVE

The European Thyroid Imaging Reporting and Data System (EU-TIRADS) allows for selective fine needle aspiration cytology (FNAC). In 2017, EU-TIRADS was implemented as part of a nationwide standardized care bundle for thyroid cancer in Western Sweden with a population of approximately 1.7 million. The objective of this study was to investigate the clinical value of EU-TIRADS attempting to reduce the number of unnecessary FNACs in referred patients with thyroid nodules.

METHODS

The study cohort consisted of all patients referred to Sahlgrenska University Hospital due to a palpable, newly detected or growing thyroid nodules or a positron emission tomography-positive finding for examination with thyroid ultrasound and selective cytology between 2018 and 2022. Medical records on EU-TIRADS classification, corresponding FNAC results, and histopathologic diagnosis were retrospectively collected. Adherence to the EU-TIRADS guidelines, use of selective FNAC, and rate of malignancy in patients who underwent surgery were assessed.

RESULTS

In total, 1246 thyroid nodules in 990 patients were evaluated. The distributions of EU-TIRADS 2 to 5 (number [percentage]) for all examined nodules were 63 (5%), 462 (37%), 443 (36%), and 278 (22%), respectively. FNAC was omitted in 7% of the investigated patients. FNAC was performed in 124 nodules (10%) despite not fulfilling the EU-TIRADS criteria or absence of positron emission tomography-positive findings. The rate of malignancy was 33% and 1/50 in patients who underwent "unnecessary" FNAC.

CONCLUSION

Implementation of EU-TIRADS in routine management of thyroid nodules led to the selective use of FNAC; however, the clinical impact was limited. This study provides real-world data on the value and magnitude of diagnostic improvement by implementing EU-TIRADS in clinical practice.

Malignancy Risk of Follicular Neoplasm (Bethesda IV) With Variable Cutoffs of Tumor Size: A Systemic Review and Meta-Analysis

CONTEXT

The decision on diagnostic lobectomy for follicular neoplasms (FN) is challenging.

OBJECTIVE

This meta-analysis investigates whether an appropriate size cutoff exists for recommending surgery for thyroid nodules diagnosed as FN by fine needle aspiration.

METHODS

The Ovid-Medline, EMBASE, Cochrane, and KoreaMed databases were searched for studies reporting the malignancy rate of FN/suspicious for FN (FN/SFN) according to tumor size, using search terms "fine needle aspiration," "follicular neoplasm," "lobectomy," "surgery," and "thyroidectomy."

RESULTS

Fourteen observational studies comprising 2016 FN/SFN nodules with postsurgical pathologic reports were included, and 2 studies included malignancy rates with various tumor sizes. The pooled malignancy risk of FN/SFN nodules according to size was: odds ratio (OR) 2.29 (95% CI, 1.68-3.11) with cutoff of 4 cm (9 studies), OR 2.39 (95% CI, 1.45-3.95) with cutoff of 3 cm (3 studies), and OR 1.81 (95% CI, 0.94-3.50) with cutoff of 2 cm (5 studies). However, tumors ≥2 cm also showed a higher risk (OR 2.43; 95% CI, 1.54-3.82) based on the leave-one-out meta-analysis after removal of 1 influence study. When each cutoff size was evaluated by summary receiver operating characteristic (sROC) curves, the cutoff of 4 cm showed the highest summary area under the curve (sAUC, 0.645) compared to other cutoffs (sAUC, 0.58 with 2 cm, and 0.62 with 3 cm), although there was no significant difference.

CONCLUSION

Although the risk of malignancy increases with increasing tumor size, the risk remains significant at all tumor sizes and no cutoff limit can be recommended as a decision-making parameter for diagnostic surgery in Bethesda IV thyroid nodules.

Diagnostic performance of ultrasound risk stratification systems on thyroid nodules cytologically classified as indeterminate: a systematic review and meta-analysis

PURPOSE

Ultrasound (US) risk stratification systems (RSSs) are increasingly being utilized for the optimal management of thyroid nodules, including those with indeterminate cytology. The goal of this study was to evaluate the category-based diagnostic performance of US RSSs in identifying malignancy in indeterminate nodules.

METHODS

This systematic review and meta-analysis was registered on PROSPERO (CRD42021266195). PubMed, EMBASE, and Web of Science were searched through December 1, 2022. Original articles reporting data on the performance of US RSSs for indeterminate nodules were included. The numbers of nodules classified as true negative, true positive, false negative, and false positive were extracted.

RESULTS

Thirty-three studies evaluating 7,225 indeterminate thyroid nodules were included. The diagnostic accuracy was quantitatively synthesized using a Bayesian bivariate model based on the integrated nested Laplace approximation in R. For the intermediate- to high-risk category, the sensitivity levels of the American College of Radiology, the American Thyroid Association, the European Thyroid Association, the Korean Thyroid Association/Korean Society of Thyroid Radiology, and Kwak et al. were found to be 0.80, 0.72, 0.76, 0.96, and 0.97, respectively. The corresponding specificity measurements were 0.36, 0.50, 0.49, 0.28, and 0.17. Furthermore, for the high-risk category, the sensitivity values were 0.40, 0.46, 0.55, 0.47, and 0.10, while the specificity levels were 0.91, 0.90, 0.71, 0.91, and 0.99, respectively.

CONCLUSION

The overall diagnostic performance of the US RSSs was moderate in the differentiation of indeterminate nodules.

Clinico-cytopathological subcategorization in thyroid nodules of atypia of undetermined significance/follicular lesion of undetermined significance using the TIRADS and Bethesda classifications

Introduction

Bethesda category III - atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) is a heterogeneous class of the Bethesda system for thyroid nodules. In order to clarify the therapeutic road for clinicians, this category was subclassified based on the cytopathological features. In this study, we evaluated the risk of malignancy, surgical outcome, demographic characteristics, and correlation of ultrasound features with the final outcome in patients with thyroid nodules based on AUS/FLUS subclassification.

Method

After evaluating 867 thyroid nodules from three different centers, 70 (8.07%) were initially diagnosed as AUS/FLUS. The cytopathologists re-interpreted the FNA samples and subclassified them into five subcategories: architectural atypia, cytologic atypia, cytologic and architectural atypia, and Hürthle cell AUS/FLUS, and atypia, which was not specified. Based on the suspicious ultrasound features, an appropriate ACR TI-RADS score was allocated to each nodule. Finally, the malignancy rate, surgical outcomes, and ACR TI-RADS scores were evaluated among Bethesda category III nodules.

Results

Among the 70 evaluated nodules, 28 (40%) were subclassified as Hürthle cell AUS/FLUS, 22 (31.42%) as cytologic and architectural atypia, 8 (11.42%) as architectural atypia, 7 (10%) as cytologic atypia, and 5 (7.14%) as atypia which was not specified. The overall malignancy rate was 34.28%, and the architectural atypia and Hürthle cell nodules displayed lower malignancy compared to other groups (P-Value<0.05). Utilizing ACR TI-RADS scores showed no statistical significance between Bethesda III subcategorization and ACR TI-RADS scores. However, ACR TI-RADS can be a reliable predictor for Hürthle cell AUS/FLU nodules.

Conclusion

ACR TI-RADS helps evaluate malignancy only in the Hürthle cell AUS/FLUS subcategory of AUS/FLUS. Besides, cytopathological reporting based on the suggested AUS/FLUS subclassification could help clinicians take appropriate measures to manage thyroid nodules.

Does a three-degree hypoechogenicity grading improve ultrasound thyroid nodule risk stratification and affect the TI-RADS 4 category? A retrospective observational study

Objective

The aim of this study was to determine whether classifying hypoechogenicity in three degrees (mild, moderate, and marked) could improve the distinction between benign and malignant nodules and whether such an approach could influence Category 4 of the Thyroid Imaging Reporting and Data System (TI-RADS).

Materials and methods

In total, 2,574 nodules submitted to fine needle aspiration, classified by the Bethesda System, were retrospectively assessed. Further, a subanalysis considering solid nodules without any additional suspicious findings (n = 565) was performed with the purpose of evaluating mainly TI-RADS 4 nodules.

Results

Mild hypoechogenicity was significantly less related to malignancy (odds ratio [OR]: 1.409; CI: 1.086-1.829; p = 0.01), compared to moderate (OR: 4.775; CI: 3.700-6.163; p < 0.001) and marked hypoechogenicity (OR: 8.540; CI: 6.355-11.445; p < 0.001). In addition, mild hypoechogenicity (20.7%) and iso-hyperechogenicity (20.5%) presented a similar rate in the malignant sample. Regarding the subanalysis, no significant association was found between mildly hypoechoic solid nodules and cancer.

Conclusion

Stratifying hypoechogenicity into three degrees influences the confidence in the assessment of the rate of malignancy, indicating that mild hypoechogenicity has a unique low-risk biological behavior that resembles iso-hyperechogenicity, but with minor malignant potential when compared to moderate and marked hypoechogenicity, with special influence on the TI-RADS 4 category.

Optimization of the Management of Category III Thyroid Nodules Using Repeat FNA and TIRADS

The aim of the study was to examine the benefits of the joint use of repeat FNA (rFNA) and EU-TIRADS in category III nodules in relation to the kind of atypia: nuclear vs. architectural (denoted by AUS and FLUS respectively). The study included 127 AUS and 1739 FLUS nodules with a known category of EU-TIRADS. Repeat FNA was performed in 82 AUS and 934 FLUS nodules of which 57 and 515 were excised, respectively. AUS nodules had higher malignancy risk than FLUS nodules. EU-TIRADS showed higher accuracy for AUS nodules, the opposite to rFNA, that had higher accuracy for FLUS nodules. The combined criterion for AUS nodules (at least rFNA-V or EU-TIRADS-4) maximized sensitivity (92.3%) with acceptable specificity (70.0%); OR: 28.0. In the case of FLUS nodules, the combined criterion (rFNA-V or EU-TIRADS-5) maximized specificity (95.2%) with 57.7% sensitivity and a low percentage (13.9%) of positive nodules, OR: 27.0. In both types of nodules, the low risk category in EU-TIRADS and benign result of rFNA excluded cancer. Concluding, category III nodules with and without nuclear atypia differ in their risk of malignancy and, consequently, diagnostic criteria adopted for the evaluation of these nodules with rFNA and EU-TIRADS should be specific to AUS and FLUS nodules.

Utility of mutational analysis for risk stratification of indeterminate thyroid nodules in a real-world setting

OBJECTIVE

American Thyroid Association (ATAn) 2015 guidelines recommend repeat fine-needle aspiration with molecular marker profiling (MMP) or diagnostic lobectomy in thyroid nodules yielding atypia of unknown significance/follicular lesion of unknown significance (AUS/FLUS) or follicular neoplasm/suspicious for follicular neoplasm (FN/SFN) cytology. Our objective is to describe the molecular profiles and histological correlates of these cytologically indeterminate nodules (CIN) to aid risk stratification.

DESIGN

Retrospective chart review.

PATIENTS

Adults with CIN that underwent MMP from 2017 to 2020.

MEASUREMENTS

Pearsons' χ² , Fisher's exact test, nonparametric testing and multiple regression analysis were performed.

RESULTS

A total of 89 CIN underwent mutational analysis. Of 55% (n = 49) were Bethesda class III AUS/FLUS and 45% (n = 40) were Bethesda class IV FN/SFN. The US phenotype of a CIN was isoechoic (53%) or hypoechoic (32%) with well-defined margins (98%), absence of calcifications (75%) and mildly increased internal vascularity (70%). A total of 84% and 87% of nodules were classified as mild/moderate or low/intermediate risk per the Thyroid Imaging Reporting and Data System and ATA classifications, respectively. Based on the Thyroseq patient management resource, 6.7% (n = 6) of nodules had a high predicted probability of cancer (≥95%), 41.6% (n = 37) were intermediate probability (40%-94%) and 51.7% (n = 46) were low probability (<40%). MMP revealed positive mutations in 45% (n = 40) of nodules, with 71% demonstrating RAS mutations. Of the nodules that underwent resection (n = 38), 39% (n = 15) had malignant pathology. Increasing the threshold to recommend surgical resection to a Thyroseq predicted probability of cancer to ≥50%, had a 100% sensitivity and 65% specificity for detecting malignant nodules (area under the ROC curve: 0.86). The positive predictive value was 37% and the negative predictive value was 100%.

CONCLUSION

US phenotypes of CIN nodules were variable and did not aid in differentiating malignant from benign nodules. Of the CIN nodules with a positive MMP, most were RAS and had a benign pathology. With the exception of high-risk genetic markers for malignancy, the threshold to recommend surgical resection should be raised for CIN. Further studies to improve risk stratification in these nodules are required.

Approach to Bethesda system category III thyroid nodules according to US-risk stratification

This study evaluated how to manage Bethesda category III (Bethesda III) (atypia of undetermined significance/follicular lesion of undetermined significance [AUS/FLUS]) thyroid nodules according to the Korean Thyroid Imaging Reporting and Data System (K-TIRADS) to reduce unnecessary surgeries. A total of 161 thyroid nodules diagnosed as Bethesda III underwent surgery from 2016 to 2019. Ultrasonography-guided fine-needle aspiration (US-FNA) or core needle biopsy (CNB) was used for repeat examination. K-TIRADS category was assigned to the thyroid nodules. The proportion of malignancy in Bethesda III nodules confirmed by surgery were significantly increased in proportion relative to K-TIRADS with 60.0% low suspicion, 88.2% intermediate suspicion, and 100% high suspicion nodules (p < 0.001). The proportion of malignancy in AUS and FLUS were significantly different (94.2% vs. 40.0% p = 0.003). The proportion of malignancy in AUS increased with K-TIRADS categories, but there was no difference in FLUS. All K-TIRADS high suspicion nodules were AUS as papillary carcinomas (99%), while 80% of FLUS nodules and 50% of follicular carcinomas showed K-TIRADS low suspicion. In 116 nodules with repeat FNA or CNB after initial Bethesda III results, the conclusive result rate was significantly increased in proportion to K-TIRADS with 58.3% low suspicion, 83.3% intermediate suspicion, and 88.8% high suspicion nodules (p = 0.015). K-TIRADS low suspicion nodules of Bethesda III nodules should be managed after risk-benefit consideration rather than immediate surgery or repeat examination. K-TIRADS for Bethesda III nodules can predict papillary carcinoma well, but not follicular carcinoma.

2021 Korean Thyroid Imaging Reporting and Data System and Imaging-Based Management of Thyroid Nodules: Korean Society of Thyroid Radiology Consensus Statement and Recommendations

Incidental thyroid nodules are commonly detected on ultrasonography (US). This has contributed to the rapidly rising incidence of low-risk papillary thyroid carcinoma over the last 20 years. The appropriate diagnosis and management of these patients is based on the risk factors related to the patients as well as the thyroid nodules. The Korean Society of Thyroid Radiology (KSThR) published consensus recommendations for US-based management of thyroid nodules in 2011 and revised them in 2016. These guidelines have been used as the standard guidelines in Korea. However, recent advances in the diagnosis and management of thyroid nodules have necessitated the revision of the original recommendations. The task force of the KSThR has revised the Korean Thyroid Imaging Reporting and Data System and recommendations for US lexicon, biopsy criteria, US criteria of extrathyroidal extension, optimal thyroid computed tomography protocol, and US follow-up of thyroid nodules before and after biopsy. The biopsy criteria were revised to reduce unnecessary biopsies for benign nodules while maintaining an appropriate sensitivity for the detection of malignant tumors in small (1-2 cm) thyroid nodules. The goal of these recommendations is to provide the optimal scientific evidence and expert opinion consensus regarding US-based diagnosis and management of thyroid nodules.

Diagnosing thyroid nodules with atypia of undetermined significance/follicular lesion of undetermined significance cytology with the deep convolutional neural network

To compare the diagnostic performances of physicians and a deep convolutional neural network (CNN) predicting malignancy with ultrasonography images of thyroid nodules with atypia of undetermined significance (AUS)/follicular lesion of undetermined significance (FLUS) results on fine-needle aspiration (FNA). This study included 202 patients with 202 nodules ≥ 1 cm AUS/FLUS on FNA, and underwent surgery in one of 3 different institutions. Diagnostic performances were compared between 8 physicians (4 radiologists, 4 endocrinologists) with varying experience levels and CNN, and AUS/FLUS subgroups were analyzed. Interobserver variability was assessed among the 8 physicians. Of the 202 nodules, 158 were AUS, and 44 were FLUS; 86 were benign, and 116 were malignant. The area under the curves (AUCs) of the 8 physicians and CNN were 0.680–0.722 and 0.666, without significant differences (P > 0.05). In the subgroup analysis, the AUCs for the 8 physicians and CNN were 0.657–0.768 and 0.652 for AUS, 0.469–0.674 and 0.622 for FLUS. Interobserver agreements were moderate (k = 0.543), substantial (k = 0.652), and moderate (k = 0.455) among the 8 physicians, 4 radiologists, and 4 endocrinologists. For thyroid nodules with AUS/FLUS cytology, the diagnostic performance of CNN to differentiate malignancy with US images was comparable to that of physicians with variable experience levels.

Macrocalcifications Do Not Alter Malignancy Risk Within the American Thyroid Association Sonographic Pattern System When Present in Non-High Suspicion Thyroid Nodules

Background: The American Thyroid Association Sonographic Pattern System (ATASPS) depicts five levels of suspicion for malignancy based on the sonographic appearance of a thyroid nodule. However, 3-37% of nodules are non-classifiable when the combination of grayscale findings is not depicted by the ATASPS. The only calcifications included in the ATASPS are in solid hypoechoic high suspicion (HS) nodules and include both microcalcifications and peripheral interrupted calcifications with soft tissue extrusion. Non-hypoechoic nodules with these and other calcification patterns, which we defined as non-high suspicion calcifications (NHSC), are not classifiable by ATASPS. We assessed the effect of assigning an ATASPS risk level to nodules with NHSC based on analysis of their other grayscale features. Methods: A retrospective review of 728 consecutively biopsied nodules was performed. Nodules were classified by ATASPS as HS, intermediate suspicion (IS), low suspicion (LS), or very low suspicion (VLS); other nodules with patterns not described by ATASPS were non-classifiable (NC). If NC was due to NHSC, the nodule was assigned an ATASPS by analysis of grayscale features alone. Cytology and pathology results were correlated with assigned ATASPS level. Results: A NC pattern was observed in 144 of the 728 nodules (20%). Of these, 101/144 (70%) had NHSC and the assigned ATASPS was IS (n = 18), LS (n = 62) and VLS (n = 21). The distribution of cytology diagnoses within this group was similar to classifiable nodules (IS p = 0.13, LS p = 0.55, VLS p = 0.44). The majority of NHSC (n = 92, 91%) were macrocalcifications (large central or linear dystrophic calcifications); however, 9 LS pattern nodules had punctate echogenic foci, possibly representing microcalcifcations, with an estimated cancer prevalence of 19% (vs. 10% for total LS group, p = 0.24). The remaining NC nodules (43/144, 30%) included solid nodules with heterogeneous echogenicity (n = 30) or presence of a complete circumferential rim calcification, limiting further sonographic assessment (n = 13). Malignancy was identified in 11 out of 43 (26%) of these [9/30 (30%) heterogeneous solid and 2/13 (15%) with complete rim calcifications]. Conclusions: Macrocalcifications accounted for the majority of NHSC and these did not alter the expected ATASPS malignancy risk based on grayscale features.

Combining the American Thyroid Association's Ultrasound Classification with Cytological Subcategorization Improves the Assessment of Malignancy Risk in Indeterminate Thyroid Nodules

Background: The risk of malignancy (RoM) of indeterminate thyroid nodules (ITNs) shows a high variability in interinstitutional cohorts. The RoM is partially associated with the cytological degree of atypia and the ultrasound (US) pattern. This study evaluated the cancer risk of ITNs by jointly considering the cytological subcategory and the American Thyroid Association (ATA)-based US risk classification. Methods: This study features a retrospective cohort from two Brazilian centers comprising 238 ITNs with confirmed outcomes. US classification, according to ATA-based guidelines, and cytological subcategorization were determined. The cytological subgroups were as follows: (1) nuclear atypia (NA) related to papillary thyroid carcinoma (PTC) but insufficient to categorize the cytology as suspicious for malignancy; (2) architectural atypia without NA (AA); (3) both architectural and nuclear atypia (ANA); (4) oncocytic pattern (OP) without NA; and (5) NA not related to PTC (NANP). NA was divided into three subgroups: nuclear size and shape, nuclear membrane appearance, and/or chromatin aspects. Results: The overall frequency of malignancy was 39.5%. Among the cytological subcategories, the highest RoM was related to the NA (43.9%) and to the ANA (43.5%), followed by AA (29.4%), and OP (9.4%). NA was positively and independently associated with cancer (odds ratio [OR]: 4.5; confidence interval [CI: 1.2-16.6]) as was the occurrence of ANA (OR 6.6 [CI 1.5-29.5]). AA and OP were not independently associated with cancer. Both ATA-based high- and intermediate-risk categories showed an independent association with cancer (OR 6.8 [CI 2.9-15.5] and OR: 2.6 [CI 1.1-5.8], respectively). ITNs with cytological findings of NA or ANA when combined with intermediate US patterns had RoM values of 47.5% and 56.7%, respectively. Both cytological subcategories, when combined with the ATA high-suspicion class reached an RoM >70%. The type of NA with the highest odds for cancer was related to the nuclear membrane (OR 11.5). Conclusions: The RoM of ITNs can reach almost 80% when both NA and ATA-based high-risk US features are present. The presence of such cytological features also increased the RoM in the ATA-based intermediate-risk US category. In addition, AA and OP were not independently related to higher cancer risk. These results strengthen the recommendations for combing cytological subcategorization and US risk classification in the workup for ITNs before the decision of a molecular testing, clinical observation, or diagnostic surgery.

Usability of EU-TIRADS in the Diagnostics of Hürthle Cell Thyroid Nodules with Equivocal Cytology

The aim of this study was to compare the diagnostic effectiveness of EU-TIRADS in two groups of nodules with equivocal cytology (categories III-V of Bethesda system), with and without Hürthle cells (HC and non-HC). The study included 162 HC and 378 non-HC nodules with determined histopathological diagnosis (17.9% and 15.6% cancers). In both groups calculated and expected risk of malignancy (RoM) for high, intermediate and benign risk categories of EU-TIRADS were concordant. RoM for low risk category was higher than expected in both groups, but especially in HC (HC: 13.9%, non-HC: 7.0%, expected: 2-4%). The majority of cancers in HC of that category were follicular thyroid carcinomas (FTC) and Hürthle cell thyroid carcinoma (HTC) (60.0% vs. non-HC: 16.7%). The diagnostic efficacy of EU-TIRADS was lower in HC (the area under the receiver operating characteristics curve (AUC): 0.621, sensitivity (SEN): 44.8%, specificity (SPC): 78.9% for high risk threshold) than in non-HC (AUC: 0.711, SEN: 61.0%, SPC: 77.7%). AUC was the highest for category V (AUC > 0.8, both groups) and the lowest for category IV (inefficient, both group). If intermediate risk category was interpreted as an indication for surgery, 25% of cancers from category III and 21.4% from category IV would not be treated in the HC group (0.0% and 7.4% from non-HC group, respectively). EU-TIRADS does not aid making clinical decisions in patients with cytologically equivocal HC nodules, particularly those classified into category IV of Bethesda System for Reporting Thyroid Cytopathology (BSRTC).

Diagnostic Value of Six Thyroid Imaging Reporting and Data Systems (TIRADS) in Cytologically Equivocal Thyroid Nodules

The aim was to compare the usefulness of selected thyroid sonographic risk-stratification systems in the diagnostics of nodules with indeterminate/suspicious cytology or unequivocal cytology in a population with a history of iodine deficiency. The diagnostic efficacy of ACR-TIRADS (the American College of Radiology Thyroid Imaging Reporting and Data Systems), EU-TIRADS (European Thyroid Association TIRADS), Korean-TIRADS, Kwak-TIRADS, AACE/ACE-AME-guidelines (American Association of Clinical Endocrinologists/ American College of Endocrinology-Associazione Medici Endocrinologi guidelines) and ATA-guidelines (American Thyroid Association guidelines) was evaluated in 1000 nodules with determined histopathological diagnosis: 329 FLUS/AUS (10.6% cancers), 167 SFN/SHT (11.6% cancers), 44 SM (77.3% cancers), 298 BL (benign lesions), 162 MN (malignant neoplasms). The percentage of PTC (papillary thyroid carcinoma) among cancers was higher in Bethesda MN (86.4%) and SM (suspicion of malignancy) nodules (91.2%) than in FLUS/AUS (57.1%, p < 0.005) and SFN/SHT (suspicion of follicular neoplasm/ suspicion of Hürthle cell tumor) nodules (36.8%, p < 0.001). TIRADS efficacy was higher for MN (AUC: 0.827-0.874) and SM nodules (AUC: 0.775-0.851) than for FLUS/AUS (AUC: 0.655-0.701) or SFN/SHT nodules (AUC: 0.593-0.621). FLUS/AUS (follicular lesion of undetermined significance/ atypia of undetermined significance) nodules assigned to a high risk TIRADS category had malignancy risk of 25%. In the SFN/SHT subgroup none TIRADS category changed nodule's malignancy risk. EU-TIRADS and AACE/ACE-AME-guidelines would allow diagnosing the highest number of PTC, FTC (follicular thyroid carcinoma), HTC (Hürthle cell carcinoma), MTC (medullary thyroid carcinoma). The highest OR value was for Kwak-TIRADS (12.6) and Korean-TIRADS (12.0). Conclusions: TIRADS efficacy depends on the incidence of PTC among cancers. All evaluated TIRADS facilitate the selection of FLUS/AUS nodules for the surgical treatment but these systems are not efficient in the management of SFN/SHT nodules.

Usage and Diagnostic Yield of Fine-Needle Aspiration Cytology and Core Needle Biopsy in Thyroid Nodules: A Systematic Review and Meta-Analysis of Literature Published by Korean Authors

Objectives

The usefulness of core needle biopsy (CNB) for the diagnosis of thyroid nodules remains controversial, and preferences vary across hospitals. The purpose of this study was to assess the actual use of CNB in Korea and to analyze the advantages and disadvantages of CNB through a systematic review and meta-analysis of papers published by Korean authors.

Methods

A meta-analysis of full-text publications published in English presenting data from Korea retrieved from the Embase literature database was performed.

Results

CNB led to a significantly lower proportion of non-diagnostic results than fine-needle aspiration (FNA). However, the frequency of atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) did not decrease as a result of performing CNB in nodules with initial AUS/FLUS results, while it increased in consecutive cases. A subcategory analysis of AUS/FLUS showed that the increased frequency of AUS/FLUS findings on CNB was due to more frequent diagnoses of architectural atypia and follicular neoplasm, which resulted in a higher frequency of inconclusive findings in consecutive cases compared to FNA. Hospitals favoring CNB had a higher proportion of AUS/FLUS diagnoses. Although the complication rate did not differ significantly between CNB and FNA, serious complications of CNB did occur.

Conclusion

A reduced frequency of non-diagnostic results may be a definite advantage of CNB over FNA. However, the increased frequency of diagnoses of architectural atypia and follicular neoplasm should be considered when selecting CNB as a diagnostic tool.

A Novel Risk Stratification System for Thyroid Nodules With Indeterminate Cytology-A Pilot Cohort Study

Background: Thyroid ultrasound (US), fine needle aspiration biopsy (FNAB), and molecular testing have been widely used to stratify the risk of malignancy in thyroid nodules. The goal of this study was to investigate a novel diagnostic approach for cytologically indeterminate thyroid nodules (ITN) based upon a combination of US features and genetic alterations. Methods: We performed a pilot cohort study of patients with ITN (Bethesda III/IV), who underwent surgical treatment. Based on standardized sonographic patterns established by the American Thyroid Association (ATA), each ITN received an US score (X_US), ranging between 0 and 0.9 according to its risk of thyroid cancer (TC). DNA and RNA were extracted from pathologic material, available for all patients, and subjected to Oncomine™ Comprehensive Assay v2 (OCAv2) next-generation sequencing. Each genetic alteration was annotated based on its strength of association with TC and its sum served as the genomic classifier score (X_GC). The total risk score (TRS) was the sum of X_US and X_GC. ROC curves were generated to assess the diagnostic accuracy of X_US, X_GC, and TRS. Results: The study cohort consisted of 50 patients (39 females and 11 males), aged 47.5 ± 14.8 years. Three patients were excluded due to molecular testing failure. Among the remaining 47 patients, 28 (59.6%) were diagnosed with TC. BRAFV600E was the most common mutation in papillary TC, PAX8-PPARG fusion was present in NIFTP, pathogenic variants of SLX4, ATM, and NRAS were found in Hürthle cell TC and RET mutations in medullary TC. The diagnostic accuracy of X_GC and TRS was significantly higher compared with X_US (88 vs. 62.5%, p < 0.001; 85.2 vs. 62.5%, p < 0.001, respectively). However, this increased accuracy was due to significantly better sensitivity (80.7 vs. 34.6%, p < 0.001; 84.6 vs. 34.6%, p < 0.001, respectively) without improved specificity (94.7 vs. 90%, p = 0.55; 85.7 vs. 90%, p = 0.63, respectively). Conclusion: Molecular testing might not be necessary in ITN with high-risk US pattern (X_US = 0.9), as specificity of TC diagnosis based on Xus alone is sufficient and not improved with molecular testing. OCAv2 is useful in guiding the management of ITN with low-to-intermediate risk US features (X_US < 0.9), as it increases the accuracy of TC diagnosis.

ACR TI-RADS and ATA US scores are helpful for the management of thyroid nodules with indeterminate cytology

BACKGROUND

Cytologically indeterminate thyroid nodules currently present a challenge for clinical decision-making. The main aim of our study was to determine whether the classifications, American College of Radiology (ACR) TI-RADS and 2015 American Thyroid Association (ATA) guidelines, in association with The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC), could be used to stratify the malignancy risk of indeterminate thyroid nodules and guide their clinical management.

METHODS

The institutional review board approved this retrospective study of a cohort of 140 thyroid nodules in 139 patients who were referred to ultrasound-guided fine-needle aspiration cytology (FNAC) from January 2012 to June 2016 with indeterminate cytological results (44 Bethesda III, 52 Bethesda IV and 44 Bethesda V) and in whom pre-FNAC thyroid US images and histological results after surgery were available. Each included nodule was classified by one radiologist blinded to the cytological and histological diagnoses according to the ACR TIRADS scores and the US patterns as recommended in the 2015 ATA guidelines. The risk of malignancy was estimated for Bethesda, TI-RADS scores, ATA US patterns and their combination.

RESULTS

Of the 140 indeterminate thyroid nodules examined, 74 (52.9%) were histologically benign. A different rate of malignancy (p < 0.001) among Bethesda III, IV and V was observed. The rate of malignancy increased according to the US suspicion categories (p < 0.001) in both US classifications (TI-RADS and ATA). Thyroid nodules classified as Bethesda III and the lowest risk US categories (very low, low and intermediate suspicion by ATA and 2, 3 and 4a by TI-RADS) displayed a sensitivity of 95.3% for both classifications and a negative predictive value of 94.3 and 94.1%, respectively. The highest risk US categories (high suspicion by ATA and 4b,4c and 5 by TI-RADS) were significantly associated with cancer (odds ratios [ORs] 14.7 and 9.8, respectively).

CONCLUSIONS

Ultrasound classifications, ACR TI-RADS and ATA guidelines, may help guide the management of indeterminate thyroid nodules, suggesting a conservative approach to nodules with low-risk US suspicion and Bethesda III, while molecular testing and surgery should be considered for nodules with high-risk US suspicion and Bethesda IV or V.

Approach to cytological indeterminate thyroid nodules

The indeterminate thyroid nodules diagnosed by fine-needle aspiration cytology (FNAC)represents a problem for both cytopathologists and clinicians. The former sometimes use this diagnostic category as a sort of basket, putting in cases that they do not know exactly how to classify. The latter are faced with a highly variable risk of malignancy and consequently the management remains a challenge. On the histopathological side, the new WHO classification of tumors of the thyroid introduced the concept of tumors with uncertain and low malignant potential, and the concept of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), whose prognosis and management are still to be completely elucidated. While the risk of malignancy of the indeterminate diagnostic category has decreased due to the re-classification of certain types of papillary thyroid carcinomas of the follicular variant into a low malignant potential form (the NIFTP), cases diagnosed cytologically as indeterminate will probably increase in the future to avoid false positive diagnosis. Thus, the indeterminate thyroid diagnostic category still remains a challenge, both at the diagnostic level and for its management. The new version of the Bethesda system for reporting thyroid cytopathology suggests managing these patients with a repeat FNA, diagnostic lobectomy and/or molecular testing.

Evaluation of malignancy with thyroid imaging reporting and data system (TI-RADS) in thyroid nodules with persistent nondiagnostic cytology

Background/aim

We aimed to evaluate the utility of thyroid imaging reporting and data system (TI-RADS) in prediction of malignancy in thyroid nodules with persistent nondiagnostic (ND) cytology.

Materials and methods

A total of 246 thyroid nodules which were surgically removed and had at least two fine-needle aspirations (FNAs) with ND cytology were included in this study. Ultrasonography features and TI-RADS scores were recorded.

Results

Of 246 nodules, 218 (88.6%) had benign and 28 (11.4%) had malignant final histopathology. Frequencies of taller than wide shape, solidity, hypoechogenicity, microcalcifications, and presence of irregular borders were similar between benign and malignant nodules (P > 0.05). The number of nodules categorized as TI-RADS 3, 4a, 4b, and 4c were 12 (4.9%), 53 (21.5%), 104 (42.3%), and 77 (31.3%), respectively. There was not any nodule in TI-RADS 5 category. Malignancy rates of categories 3, 4a, 4b, and 4c were 0%, 13.2%, 9.6%, 14.3%, respectively. No significant differences were detected in TI-RADS categories between benign and malignant nodules (P > 0.05).

Conclusion

In this study, we did not demonstrate any suspicious ultrasound (US) finding predictive for malignancy in thyroid nodules with persistent ND cytology and did not determine any difference between malignant and benign nodules regarding TI-RADS scores. Whereas, we found that thyroid nodules in 4a, 4b, and 4c TI-RADS categories had higher malignancy rates than those previously reported in ND cytology. We think that TI-RADS categories in thyroid nodules with persistent ND cytology can be helpful in treatment decision.

USING THE ATA AND ACR TI-RADS SONOGRAPHIC CLASSIFICATIONS AS ADJUNCTIVE PREDICTORS OF MALIGNANCY FOR INDETERMINATE THYROID NODULES

Objective: Thyroid nodules with indeterminate cytology pose management challenges in clinical practice. The aim of this study was to determine the efficacy of ultrasound features in navigating clinical decision making in thyroid nodules with indeterminate cytology. Methods: We retrospectively reviewed ultrasound imaging from 186 adult patients with thyroid nodules and indeterminate cytology who underwent thyroidectomy at a quaternary hospital from 2010-2017. All nodules were classified based on the American Thyroid Association (ATA) and 2017 American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS). Nodules were included if good quality pre-operative ultrasound imaging and surgical pathology were available. Results: A total of 202 thyroid nodules were included. The median age was 57 years; 82.8% were female. Risk of malignancy (ROM) in resected nodules with Bethesda 3 and 4 cytology was 19.4% and 30.3%, respectively. ATA high-suspicious and TI-RADS 5 nodules had high ROM, 100% in both systems for Bethesda 3 nodules; 66.7% and 50.0%, respectively, for Bethesda 4 nodules. For ATA very-low suspicious/TI-RADS 1 and 2, ROM was 0%. ROM in ATA low-suspicious/TI-RADS 3 nodules with Bethesda 3 cytology was lower (15.2% and 16.0%, respectively) than Bethesda 4 cytology (33.8% and 34.3%, respectively). ATA intermediate-suspicious/TI-RADS 4 nodules with Bethesda 4 cytology had a lower ROM (11.1% and 18.2%, respectively) than Bethesda 3 cytology (28.6 % and 31.6%, respectively). Conclusion: Using either the ATA or the TI-RADS system to risk-stratify nodules with indeterminate cytology may help clinicians plan better for additional diagnostic testing and treatment. Abbreviations: ACR = American College of Radiology; ATA = American Thyroid Association; AUS = atypia of undetermined significance; FLUS = follicular lesion of undetermined significance; FN = follicular neoplasm; PPV = positive predictive value; ROM = risk of malignancy; SFN = suspicious for follicular neoplasm; TI-RADS = Thyroid Imaging Reporting and Data System.

Diagnostic Performance of Ultrasound Patterns by K-TIRADS and 2015 ATA Guidelines in Risk Stratification of Thyroid Nodules and Follicular Lesions of Undetermined Significance

OBJECTIVE. The objective of our study was to assess the malignancy rates of thyroid nodules in the cytologically determined subclass of atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS) and to assess the diagnostic performance of ultrasound (US) patterns defined by the Korean Thyroid Imaging Reporting and Data System (K-TIRADS) and the 2015 American Thyroid Association (ATA) guidelines for risk stratification of AUS/FLUS nodules. MATERIALS AND METHODS. From January 2010 to December 2016, 1340 thyroid nodules were diagnosed as AUS/FLUS via fine-needle aspiration biopsy. Of these, 683 cytopathologically confirmed nodules were included in this study. Each nodule was assigned to a category and US pattern, as defined by the K-TIRADS and ATA guidelines. US patterns were compared between benign and malignant nodules, and malignancy rates were calculated according to the subclasses of AUS/FLUS nodules and the K-TIRADS and ATA guidelines. Predictors of malignancy were assessed using logistic regression analysis. RESULTS. The overall malignancy rate of AUS/FLUS nodules was 47.4% (324/683). There were significant differences in malignancy risk among the subclasses (p = 0.001). There were significant differences in malignancy rates according to US patterns, K-TIRADS categories, and ATA categories (p < 0.001). The malignancy rates in the K-TIRADS categories of benign, low, intermediate, and high suspicion were 0%, 1.99%, 34.66%, and 89.00%, respectively (p < 0.001). The malignancy rates in the ATA categories of benign, very low, low, intermediate, and high suspicion were 0%, 0%, 3.33%, 33.54%, and 87.67% (p < 0.001). CONCLUSION. AUS/FLUS nodules with a final diagnosis of malignancy had significantly higher rates of suspicious US features and different K-TIRADS and ATA categories than benign nodules. US categories by K-TIRADS and ATA guidelines can be useful in predicting malignancy and risk stratification, and management planning can be adjusted according to US pattern.

Validation of web-based thyroid imaging reporting and data system in atypia or follicular lesion of undetermined significance thyroid nodules

BACKGROUND

Atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) show variable malignancy risk. We validated the web-based predictive models and the scoring system by the American College of Radiology (ACR) for AUS/FLUS nodules to stratify the malignancy risk.

METHODS

From January 2011 to November 2014, 275 consecutive nodules diagnosed as AUS/FLUS were enrolled. The discrimination and calibration ability of a web-based scoring with inclusion of biopsy result and sonographic features, old web-based scoring model without biopsy result, and ACR models were assessed.

RESULTS

The areas under the receiver operating characteristic curve of the validation set were 0.670 for the new web-based model, 0.710 for the old web-based model, and 0.732 for the ACR scoring risk-stratification model. All models were well calibrated.

CONCLUSION

The web-based scoring risk-stratification model using the combined information of ultrasonography features and biopsy result for AUS/FLUS nodules to stratify malignancy risk presents an acceptable predictive accuracy.

Clinical Parameter for Deciding the BRAFV600E Mutation Test in Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance Thyroid Nodules: US Features According to TIRADS

This study aimed to investigate the usefulness of a thyroid imaging reporting and data system (TIRADS) to select thyroid nodules with atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) cytology for additional BRAF mutation testing. Three hundred three thyroid nodules were included. Statistical analysis was performed at both patient and nodule levels according to BRAF mutation positivity and clinical factors. Univariate and multivariate logistic regression analyses were performed to assess independent associations between BRAF mutation positivity and clinical factors. Of 303 AUS/FLUS nodules, 16 (5.3%) of 303 nodules had the BRAF mutation. The frequency of the BRAF mutation according to the TIRADS was 35.7% for category 5, 10.8% for category 4c, 2.5% for category 4b, 1.1% for category 4a, and 0% for category 3 nodules (P < 0.001). On multivariate analysis, BRAF mutation positivity was significantly associated with high suspicion on the TIRADS (odds ratio, 15.247; P < 0.001). In conclusion, the ultrasonography patterns of the TIRADS can be used as a clinical parameter for deciding the BRAF mutation test in thyroid nodules with AUS/FLUS cytology.

The association between the ultrasonography TIRADS classification system and surgical pathology among indeterminate thyroid nodules

BACKGROUND

A high proportion of cytologically indeterminate, Afirma-suspicious thyroid nodules are benign. The Thyroid Imaging Reporting and Data System was proposed by the American College of Radiology in 2015 to determine appropriate management of thyroid nodules in a standardized fashion. Our aim was to determine the diagnostic value of the Thyroid Imaging Reporting and Data System in cytologically indeterminate and Afirma-suspicious nodules.

METHODS

We retrospectively queried cytopathology archives for retrospectively for thyroid fine-needle aspiration specimens obtained between February 2012 and September 2016 that were associated with the following: (1) indeterminate diagnosis, (2) ultrasonographic imaging at our institution, (3) an Afirma Gene Expression Classifier-suspicious result, and (4) surgery at our institution. We then calculated the diagnostic value of the Thyroid Imaging Reporting and Data System in predicting surgical pathology.

RESULTS

Our cohort consisted of 133 nodules among 131 patients who underwent thyroid surgery for cytologically indeterminate, Afirma-suspicious nodules. A total of 9 nodules (6.8%) were assigned TR2 "not suspicious," 25 (18.8%) TR3 "mildly suspicious," 81 (60.9%) TR4 "moderately suspicious," and 18 (13.5%) TR5 "highly suspicious." Among our cohort, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the Thyroid Imaging Reporting and Data System was 71.4%, 38.1%, 40.2%, 69.6%, and 50.4%, respectively.

CONCLUSION

Among cytologically indeterminate and Afirma-suspicious nodules, the Thyroid Imaging and Reporting and Data System was a poor predictor of final surgical pathology. Additional prospective studies are needed to validate these findings.

Cytomorphologic, Imaging, Molecular Findings, and Outcome in Thyroid Follicular Lesion of Undetermined Significance/Atypical Cell of Undetermined Significance (AUS/FLUS): A Mini-Review

OBJECTIVES

Since the introduction of the entity of "Atypical cell of undetermined significance /follicular lesion of undetermined significance" (AUS/FLUS) by The Bethesda System for Reporting Thyroid Cytology (TBSRTC) in 2007, there have been many published studies about the cytomorphologic criteria, subclassification, outcome, and management of patients with the diagnosis of AUS/FLUS. There have been many studies in different aspects of this indeterminate category, i.e., cytologic and molecular findings, ultrasonographic findings, and in some instances even core-needle biopsy to address a better and safer way of the management of patients with this fine-needle aspiration cytology diagnosis. The second edition of TBSRTC and the 2015 American Thyroid Association guidelines provide an update on the follow-up and management of AUS/FLUS. A multidisciplinary team consisting of pathologists, endocrinologists, surgeons, and radiologists should be involved in the diagnosis and management of AUS/FLUS, and all of them should be aware of the heterogeneity of this lesion for the prediction of the treatment and outcome.

STUDY DESIGN

In this review, we consider different research platforms (2008-2017) to find the best and key reports for the above-mentioned challenging aspects of AUS/FLUS.

CONCLUSION

AUS/FLUS is now a well-defined group of thyroid lesions, which can be most accurately diagnosed and managed with cytomorphology, molecular, and ancillary studies.

Thyroid Nodules with Indeterminate Cytology: Utility of the American Thyroid Association Sonographic Patterns for Cancer Risk Stratification

BACKGROUND

The 2015 American Thyroid Association (ATA) guidelines recommend using a classification based on sonographic patterns to set the size threshold for biopsies. Each pattern is associated with a distinct estimated rate of malignancy that it was hypothesized should stratify the risk of malignancy of cytologically indeterminate thyroid nodules (ITNs).

METHODS

Ultrasound images of 463 ITNs (38% atypia/follicular lesions of undetermined significance; 62% follicular neoplasms) with histological follow-up consecutively evaluated between October 2008 and June 2015 at the authors' academic cancer center were independently evaluated by three observers and classified into one of the five sonographic patterns proposed by the ATA. Nodules with sonographic patterns not defined in the classification were grouped into a non-ATA pattern category. Differences in clinical and histological findings between the sonographic patterns were assessed. The prevalence of malignancy and odds ratio for malignancy were calculated for each sonographic pattern (low and intermediate patterns were collapsed for the analysis).

RESULTS

The distribution of size and cytological diagnosis was significantly different between sonographic patterns (p < 0.001). The overall rate of malignancy was 27%. The rate of malignancy for the very low, low/intermediate, high, and non-ATA patterns were 0%, 19%, 56%, and 36%, respectively, and were all significantly different. Compared to the low/intermediate suspicion patterns, the odds ratios for malignancy were 2.35 for the non-ATA and 5.18 for the high suspicion patterns (p < 0.001). The odds ratio of the non-ATA pattern was 0.45 over the high suspicion pattern (p = 0.04). Results were similar in both cytological categories and for each observer separately. Sonographic patterns were associated with distinct histopathological profiles (p < 0.001).

CONCLUSIONS

ATA sonographic patterns are associated with distinct clinical features and pathological outcomes, and effectively stratify the cancer risk in ITNs. Thus, the ATA sonographic patterns should be used not only to set the size threshold for biopsy, but also to personalize management after the biopsy.

Factors Predicting Thyroid Malignancy in Fine Needle Aspiration Biopsy Specimens Classified as Atypia of Uncertain Significance/Follicular Lesion of Uncertain Significance

The atypia of uncertain significance/follicular lesion of uncertain significance (AUS/FLUS) category of the Bethesda system for reporting thyroid cytopathology for fine needle aspiration biopsy (FNAB) has a predicted incidence of malignancy from 5 to 15 per cent. The literature has reported that suspicious ultrasound (SUS) characteristics can assist in predicting malignancy in thyroid biopsies. Some research suggests further subdivision of AUS/FLUS into nuclear atypia predominant or follicular predominant. We hypothesized that the rate of malignancy would be higher in AUS/FLUS biopsies with SUS characteristics and in the AUS/FLUS subset classified as nuclear atypia predominant. We performed a four-year retrospective analysis of patients who underwent FNAB classified as AUS/FLUS and who subsequently underwent thyroidectomy from October 2008–October 2012. A total of 3839 thyroid FNAB were performed over the four-year period, of which 342 received AUS/FLUS classification. Of these, we identified 119 patients who underwent thyroidectomy, of which 27 (23%) malignancies were identified. Reported cytology (nuclear atypia vs follicular predominant) did not differ between patients with and without carcinomas (P = 0.33). Suspicious ultrasound appearance failed to be significantly associated with an underlying carcinoma (P = 0.14); although, nearly 70 per cent of malignancies displayed SUS compared with 50 per cent within the benign group. Ultrasound seems to have no additional value in predicting malignancy in the AUS/FLUS categorization. Further subcategorization did not aid in risk stratification of this indeterminate category. This may suggest an expanded role for ancillary technologies such as molecular markers in this challenging Bethesda system for reporting thyroid cytopathology class. Further study of these findings is warranted.

Evaluation and Management of Indeterminate Thyroid Nodules: The Revolution of Risk Stratification Beyond Cytological Diagnosis

In accordance with National Guidelines, we currently follow a linear approach to the diagnosis of thyroid nodules, with management decision based primarily on a cytological diagnosis following fine-needle aspiration biopsy. However, 25% of these biopsies render an indeterminate cytology, leaving uncertainty regarding appropriate management. Individualizing the risk of malignancy of these nodules could improve their management significantly. We summarize the current evidence on the relevance of clinical information, radiological features, cytological features, and molecular markers tests results and describe how these can be integrated to personalize the management of thyroid nodules with indeterminate cytology. Several factors can be used to stratify the risk of malignancy in thyroid nodules with indeterminate cytology. Male gender, large tumors (>4 cm), suspicious sonographic patterns, and the presence of nuclear atypia on the cytology are all associated with an increased cancer prevalence. The added value of current molecular markers in the risk stratification process needs further study because their performance seems compromised in some clinical settings and remains to be validated in others. Risk stratification is possible in thyroid nodules with indeterminate cytology using data that are often underused by current guidelines. Future guidelines should integrate these factors and personalize the recommended diagnostic and therapeutic approaches accordingly.

Diagnostic performance of ATA, BTA and TIRADS sonographic patterns in the prediction of malignancy in histologically proven thyroid nodules

INTRODUCTION

We aimed to compare the malignancy risk stratification of histologically proven thyroid nodules using the 2015 American Thyroid Association (ATA) Management Guidelines, 2014 British Thyroid Association (BTA) Guidelines for the Management of Thyroid Cancer and the Thyroid Imaging Reporting and Data System (TIRADS).

METHODS

Thyroid nodules measuring > 1 cm resected over 5.5 years were retrospectively studied. Demographic information as well as cytology and histopathology results were collected. Static ultrasonography (US) images and radiologists' reports of each resected nodules were reviewed and classified based on the above risk classification systems.

RESULTS

A total of 167 thyroid nodules from 150 patients were examined. More malignant nodules were solid (78.4% vs. 62.5%; p = 0.049) or hypoechoic (70.6% vs. 28.6%; p < 0.001), and had irregular margins (35.3% vs. 8.0%; p < 0.001), taller-than-wide morphology (9.8% vs. 2.7%; p = 0.031), microcalcifications (33.3% vs. 8.0%; p < 0.001), disrupted rim calcifications (9.8% vs. 0.9%; p = 0.012) or associated abnormal cervical lymphadenopathy (13.7% vs. 0.9%; p = 0.001) compared with benign nodules. The guidelines' diagnostic performance was: ATA - sensitivity 98.0%, specificity 17.3%, positive predictive value (PPV) 35.0%, negative predictive value (NPV) 95.0%; BTA - sensitivity 90%, specificity 50.9%, PPV 45.5%, NPV 91.8%; and TIRADS - sensitivity 94.0%, specificity 28.2%, PPV 37.3%%, NPV 91.2%.

CONCLUSION

Sonographic patterns outlined by the three guidelines displayed high sensitivity and NPV. Although isolated suspicious US features cannot predict malignancy risk, they should be considered when risk stratifying nodules that do not fit into particular sonographic patterns based on current guidelines.

Diagnostic Utility of Molecular and Imaging Biomarkers in Cytological Indeterminate Thyroid Nodules

Indeterminate thyroid cytology (Bethesda III and IV) corresponds to follicular-patterned benign and malignant lesions, which are particularly difficult to differentiate on cytology alone. As ~25% of these nodules harbor malignancy, diagnostic hemithyroidectomy is still custom. However, advanced preoperative diagnostics are rapidly evolving.This review provides an overview of additional molecular and imaging diagnostics for indeterminate thyroid nodules in a preoperative clinical setting, including considerations regarding cost-effectiveness, availability, and feasibility of combining techniques. Addressed diagnostics include gene mutation analysis, microRNA, immunocytochemistry, ultrasonography, elastosonography, computed tomography, sestamibi scintigraphy, [18F]-2-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET), and diffusion-weighted magnetic resonance imaging.The best rule-out tests for malignancy were the Afirma® gene expression classifier and FDG-PET. The most accurate rule-in test was sole BRAF mutation analysis. No diagnostic had both near-perfect sensitivity and specificity, and estimated cost-effectiveness. Molecular techniques are rapidly advancing. However, given the currently available techniques, a multimodality stepwise approach likely offers the most accurate diagnosis, sequentially applying one sensitive rule-out test and one specific rule-in test. Geographical variations in cytology (e.g., Hürthle cell neoplasms) and tumor genetics strongly influence local test performance and clinical utility. Multidisciplinary collaboration and implementation studies can aid the local decision for one or more eligible diagnostics.

Subclassification of Bethesda Atypical and Follicular Neoplasm Categories According to Nuclear and Architectural Atypia Improves Discrimination of Thyroid Malignancy Risk

BACKGROUND

Although The Bethesda System for Reporting Thyroid Cytopathology has provided clinicians with a standardized classification scheme for the diagnosis of thyroid fine-needle aspiration cytology (FNAC) specimens, the indeterminate categories of Bethesda III (B3)-atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS)-and Bethesda IV (B4)-follicular neoplasm/suspicious for follicular neoplasm (FN/SFN)-continue to pose challenges with regards to ideal diagnostic and therapeutic management. Having previously demonstrated the presence of nuclear atypia as a high-risk subgroup in B3, the objective of this study was to evaluate the malignancy rates in the B4 subgroup with nuclear atypia.

METHODS

A retrospective review of all thyroid FNACs diagnosed as B4 (FN/SFN) between 2008 and 2015 was conducted at a tertiary referral center in Singapore. Data on patient demographics, sonographic features, and final histological diagnosis were collected. This was compared to data from a previous analysis on all nodules diagnosed as B3 (AUS/FLUS) over a similar period.

RESULTS

A total of 137/309 (44.3%) and 88/111 (79.3%) FNACs diagnosed as B3 and B4, respectively, underwent surgical excision yielding final histopathological diagnoses. The malignancy rate of B4 was 31/88 (35.2%) compared to B3, which was 37/137 (27.0%). Subclassification based on the presence of architectural versus nuclear atypia showed significantly higher malignancy rates in B4 nodules with nuclear atypia (21.8% vs. 57.6%; p < 0.01). These findings corroborate previous results within the B3 category (malignancy rate of 14.7% vs. 36.8%; p < 0.01). The only sonographic features predictive of malignancy were the presence of macrocalcifications in B4 compared to irregularity of margins in B3.

CONCLUSION

The presence of nuclear atypia identifies subgroups with significant differential malignancy risks within both the B3 and B4 categories. This supports the notion that subclassification is a useful risk stratification tool that can guide diagnostic and therapeutic management of indeterminate thyroid nodules with heterogenous risk profiles.

Use of the Kwak Thyroid Image Reporting and Data System (K-TIRADS) in differential diagnosis of thyroid nodules: systematic review and meta-analysis

PURPOSE

The purpose of this systematic literature review was to assess the usefulness of the Thyroid Image Reporting and Data System (K-TIRADS) classification proposed by Kwak for differentiation of thyroid nodules.

MATERIAL AND METHODS

Four literature databases were searched for relevant articles through early January 2017. A meta-analysis was performed to calculate pooled sensitivity, specificity, positive likelihood ratio (LR+), negative likelihood ratio (LR-) and diagnostic odds ratio (DOR). The area under the curve (AUC) from the pooled receiver operating characteristic (ROC) was used to assess the usefulness of this classification for differentiation of thyroid nodules. Meta-analysis was conducted by using meta-analysis software.

RESULTS

We analysed six publications describing 10,926 nodules. Pooled sensitivity, specificity, LR+, LR-, DOR, and AUC for pooled ROC were 0.983 (95 % CI 0.976-0.989), 0.552 (95 % CI 0.542-0.562), 2.666 (95 % CI 1.692-4.198), 0.05 (95 % CI 0.035-0.072), 51.020 (95 % CI 15.241-170.79) and 0.938, respectively.

CONCLUSIONS

Kwak TIRADS has high sensitivity and low specificity. Thus, it is very useful to discard the benign cases and to reduce the number of biopsies.

KEY POINTS

• Routine, adequate standardization of thyroid nodules ultrasound classification is mandatory. • Kwak TIRADS parameters are accurate for differentiating focal thyroid lesions. • Kwak TIRADS system is simple to apply. • Kwak TIRADS system may become a useful diagnostic tool.

Malignancy Risk and Related Factors of Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance in Thyroid Fine Needle Aspiration

Atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) in thyroid fine needle aspiration (FNA) is a challenging category. The malignancy risk is different by multiple factors and subsequent management strategy is inconclusive. Therefore, we analyzed the malignancy risk of AUS/FLUS according to radiological and clinical features. A total of 687 nodules that had been initially diagnosed as AUS/FLUS were retrospectively reviewed from 6365 thyroid FNAs between 2011 and 2014. The ultrasonographic (US) features were categorized using the Korean Thyroid Imaging Reporting and Data System. Radiological and clinical features were compared according to the second FNA results or histologically confirmed results from surgery. Repeat FNA was performed on 248 (36%) nodules, and 49 (7%) nodules underwent immediate surgery. Among the 248 nodules subjected to repeated FNA, 49 (20%) nodules were diagnosed again as AUS/FLUS, 123 (50%) were found to be benign, and 47 (19%) were diagnosed as follicular neoplasm, suspicious for malignancy or malignant. Among histologically confirmed nodules, the US features were more unfavorable in malignant nodules, and hypo- or anechogenicity was associated with a higher risk of malignancy after adjusting for age, size, and other US features (P < 0.01). In conclusion, we observed that malignant nodules tended to show unfavorable US features, especially hypo- or anechogenicity. Age, sex, and thyroid function were not significantly associated with malignancy risk. We also found out that malignancy risk was not different between the group which underwent immediate operation following the AUS/FLUS diagnosis and the group which underwent repeated FNA after the initial diagnosis.

Differences in Clinical Features Between Subcategories of "Atypia/Follicular Lesion of Undetermined Significance"

Within the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC), category III (atypia or follicular lesion of undetermined significance (AUS/FLUS)) comprises specimens with heterogeneous features and the need for subcategorization has been reported. We compared the clinical features of two subgroups from within the category of AUS/FLUS to determine precise guidelines for clinicians who explain the results of fine-needle aspiration (FNA) to patients. Retrospective review was performed including data from all patients who underwent FNA with results reported as AUS/FLUS at a single tertiary hospital from January 2010 to August 2014. The results of repeated FNA, core needle biopsy, and diagnostic surgery were analyzed. Of the 903 patients with results categorized as AUS/FLUS, 500 were subcategorized as cellular atypia and 160 as architectural atypia. On repeated biopsy, diagnostic results were obtained for 78.9% patients of the cellular atypia group, compared to only 54.3% of the architectural atypia group (p < 0.0001). The rate of neoplasm or malignancy was also significantly higher in the cellular atypia group compared to the architectural atypia group (51.8 vs. 25.2%, p < 0.0001, 48.2 vs. 14.2%, p < 0.0001). Therefore, clinicians can inform patients with architectural atypia that the risk of malignancy is low. However, the high rate of non-diagnostic results on repeated biopsy makes clinical decisions difficult. The data of the present study revealed the necessity of subcategorization of category III of TBSRTC in the future.

Cytologically indeterminate thyroid nodules: increased diagnostic performance with combination of US TI-RADS and a new scoring system

To investigate the diagnostic performance of combination of ultrasound (US) thyroid imaging reporting and data system (TI-RADS) and a new US scoring system for diagnosing thyroid nodules (TNs) with indeterminate results (Bethesda categories III, IV and V) on fine-needle aspiration (FNA) cytology. 453 patients with 453 cytologically indeterminate TNs were included in this study. Multivariate analyses were performed to construct the scoring system. The diagnostic performances of TI-RADS and the combined method were evaluated and compared. Multivariate analyses revealed that marked hypoechogenicity, taller than wide shape and absence of halo sign were independent predictors for malignancy in cytologically indeterminate TNs. Scoring system was thereafter defined as follows: risk score (RS) = 3.2 x (if marked hypoechogenicity) + 2.8 x (if taller than wide shape) + 1.3 x (if absence of halo sign). Compared with TI-RADS alone, the areas under the receiver operating characteristic curves (AUC), specificity, accuracy and positive predictive value (PPV) of the combined method increased significantly with 0.731 versus 0.569, 48.5% versus 14.1%, 76.2% versus 62.3%, and 70.9% versus 59.9%, respectively (all P < 0.05). The combination of TI-RADS and new US scoring system showed superior diagnostic performances in predicting malignant TNs with indeterminate FNA cytology results in comparison with TI-RADS alone.

Risk Stratification of Thyroid Nodules With Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance (AUS/FLUS) Cytology Using Ultrasonography Patterns Defined by the 2015 ATA Guidelines

PURPOSE

The purpose of this study was to evaluate the predictive value of ultrasonography (US) patterns based on the 2015 American Thyroid Association (ATA) guidelines for malignancy in atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS) nodules.

METHODS

From January 2014 to August 2015, 133 thyroid nodules that were initially diagnosed as AUS/FLUS on fine needle aspiration (FNA) were included in this study. Each nodule was assigned a category with US patterns defined by the ATA guidelines. Clinical characteristics and US patterns were compared between the benign and malignant nodules, and malignancy rates were calculated according to the ATA guidelines.

RESULTS

The malignancy rate in the very low suspicion group was 0.0% in AUS/FLUS nodules. When applying the ATA guidelines, significant differences existed for US patterns between the benign and malignant nodules in the AUS group ( P = .032) but not the FLUS group ( P = .168).

CONCLUSIONS

Ultrasonography patterns by the 2015 ATA guidelines can provide risk stratification for nodules with AUS cytology but not for ones with FLUS cytology. For nodules with AUS/FLUS cytology with the very low suspicion pattern of the ATA guidelines, follow-up US might be recommended instead of repeat FNA.

Thyroid nodules classified as atypia or follicular lesions of undetermined significance deserve further research: Analysis of 305 surgically confirmed nodules

OBJECTIVE

The objective of the present study was to determine the malignancy risk for nodules categorised as atypia or follicular lesions of undetermined significance atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) and to investigate the predictors of malignancy.

METHODS

All nodules diagnosed as AUS/FLUS on fine needle aspiration (FNAs) performed between January 2011 and December 2015 were retrospectively reviewed. Clinical data, ultrasonographic features, follow-up data and the final pathological results were recorded. After further exclusion, only nodules that underwent surgical excision were included in the final analysis. The malignancy rate and the range of malignancy rates were calculated. Clinical and ultrasound features were examined to determine the predictors of malignancy.

RESULTS

During the study period, FNA was performed on 9938 nodules, and 1019 (10.2%) nodules were diagnosed as AUS/FLUS. After further exclusion, 976 nodules were evaluated. After the initial diagnosis of AUS/FLUS, 139 (14.2%) patients underwent surgery, 518 (53.1%) had repeated FNAs. A total of 305 (31%) had undergone surgical excision at different time points. For surgically confirmed nodules, the malignancy rate after the initial FNA was 34.5% (the lower and upper thresholds for the malignancy rate were 19.3% and 66.3%, respectively), and 37.9% after the repeated FNA. No ultrasound feature was determined as a predictor, whereas age (>55 years) was a predictor for malignancy.

CONCLUSIONS

The overall malignancy rate for nodules diagnosed as AUS/FLUS and the malignancy rate for nodules that underwent repeated FNA after AUS/FLUS were higher than the expected malignancy rates of the National Cancer Institute. It is, therefore, suggested that the current recommendations should be reconsidered.

Comparison of risk of malignancy in a subgroup with atypia of undetermined significance/follicular lesion of undetermined significance: A meta-analysis

BACKGROUND

As heterogeneous findings are included in the atypia of undetermined significance (AUS)/follicular lesion of undetermined significance (FLUS) category, differing risks of malignancy in subgroups have been reported in several articles.

METHODS

We performed a meta-analysis of full-text publications written in English found in the Embase and PubMed databases.

RESULTS

The 4-tiered subgroup proportion meta-analysis showed that the 95% confidence interval (95% CI) of the risk of malignancy in the cellular atypia group did not overlap with the other 3 subgroups and demonstrated a significant difference. Two-tiered analysis using the cytologic and architectural atypia groups showed that cytologic atypia group had a 2.64-fold increase in the risk of malignancy compared with the architectural atypia group.

CONCLUSION

The cytologic atypia had a significantly higher risk of malignancy than the architectural atypia group, and it should be considered as a separate category.

Diagnostic accuracy of Thyroid Imaging Reporting and Data System in the prediction of malignancy in nodules with atypia and follicular lesion of undetermined significance cytologies

OBJECTIVE

Thyroid Imaging Reporting and Data System (TIRADS) is a simple and reliable reporting system for the prediction of malignancy. We aimed to determine the role of TIRADS in the prediction of malignancy in subcategories of Bethesda Category III, atypia of undetermined significance (AUS) and follicular lesion of undetermined significance (FLUS).

DESIGN & PATIENTS

A total of 461 nodules with AUS cytology in 450 patients and 179 nodules with FLUS cytology in 168 patients were included. Ultrasonography (US) features and postoperative histopathology results were documented. Every suspicious US feature was scored as 1 and 0 according to the presence or not, respectively. TIRADS category of each nodule was determined.

RESULTS

In AUS subcategory, histopathologically malignant nodules had significantly different TIRADS categories compared to benign nodules (P = 0·001), but this was not the case in FLUS subcategory (P = 0·121). In AUS group, malignant nodules had significantly higher prevalance of microcalcification, hypoechogenicity and anteroposterior/transverse ratio than benign ones (P < 0·001, P < 0·001 and P = 0·003, respectively) and TIRADS categories of 4c and 5 were more frequent in malignant nodules (P < 0·05). Microcalcification, hypoechogenicity and TIRADS were found to be associated with malignancy in multivariate logistic regression analysis in this subcategory. TIRADS category ≥4c was associated with malignancy (AUC ± SE: 0·584 ± 0·028). In FLUS subcategory, there was no significant difference between histopathologically malignant and benign nodules with respect to suspicious US features (P > 0·05, all).

CONCLUSION

TIRADS seems to be useful in predicting malignancy and planning further management in the AUS subcategory, but not quite so in the FLUS subcategory.

Ultrasound is helpful to differentiate Bethesda class III thyroid nodules: A PRISMA-compliant systematic review and meta-analysis

BACKGROUND

Fine-needle aspiration (FNA) is the most dependable tool to triage thyroid nodules for medical or surgical management. However, Bethesda class III cytology, namely "follicular lesion of undetermined significance" (FLUS) or "atypia of undetermined significance" (AUS), is a major limitation of the US-FNA in assessing thyroid nodules. As the most important imaging method, ultrasound (US) has a high efficacy in diagnosing thyroid nodules. This meta-analysis aimed to assess the role of US in evaluating Bethesda class III thyroid nodules.

METHODS

With keywords "Undetermined Significance," "Bethesda Category III," "Bethesda system," "Cytological Subcategory," "AUS/FLUS," "Atypia of Undetermined Significance," and "Ultrasound/US," papers in PubMed, Cochrane Library, Medline, Web of Science, Embase, and Google Scholar from inception to December 2016 were searched. A meta-analysis of these trials was then performed for evaluating the diagnostic value of thyroid ultrasound in Bethesda Category III thyroid nodules.

RESULTS

Fourteen studies including 2405 nodules were analyzed. According to the criteria for US diagnosis of thyroid nodules in each article, with any one of suspicious features as indictors of malignancy, US had a pooled sensitivity of 0.75 (95% CI 0.72-0.78) and a pooled specificity of 0.48 (95% CI 0.45-0.50) in evaluating Bethesda Class III Nodules. The pooled diagnostic odds ratio was 10.92 (95% CI 6.04-19.74). The overall area under the curve was 0.84 and the Q* index was 0.77. With any 2 or 3 of US suspicious features as indictors of malignancy, the sensitivity and specificity were 0.77 (95% CI 0.71-0.83) and 0.54 (95% CI 0.51-0.58), 0.66 (95% CI 0.59-0.73) and 0.71 (95% CI 0.68-0.74), respectively.

CONCLUSIONS

US was helpful for differentiating benign and malignant Bethesda class III thyroid nodules, with the more suspicious features, the more likely to be malignant.

The predictive value of sonographic images of follicular lesions - a comparison with nodules unequivocal in FNA - single centre prospective study

BACKGROUND

To determine the diagnostic efficacy of ultrasonographic malignancy risk features (UMRFs) in follicular lesions (FL) in a population with low risk of malignancy in FL and to compare it with a similar analysis in a group of patients with unequivocal cytology (UC): benign lesion (BL) or malignant neoplasm (MN).

METHODS

Presence of UMRFs (hypoechogenicity, solid echostructure, taller-than-wide shape, pathological vascularization, irregular margins, microcalcifications and macrocalcifications) and their sets were assessed in 322 FL: 202 follicular lesions of undetermined significance (FLUS) and 120 suspicious for follicular neoplasm (SFN) and 300 nodules with UC: 200 BL and 100 MN, subsequently evaluated histopathologically.

RESULTS

Cancers were confirmed in 100% nodules in MN group (89.0% of them were papillary carcinomas - PTC), in 6.4% FLUS nodules (69.2% PTC), and in 10.8% SFN nodules (30.8% PTC). In the UC group all UMRFs occurred more frequently in cancers than in benign lesions. In the FL group only calcifications were found in cancers more frequently - macro and microcalcifications together: 34.6 vs. 11.5% (p = 0.001) and isolated macrocalcifications: 26.0 vs. 6.8% (p = 0.001); the presence of those features increased the basic risk of malignancy in FL more than 2 times. The presence of at least 2 of the following URMFs: hypoechogenicity, solid echostructure, any type of calcifications and suspected shape, additionally improved sensitivity.

CONCLUSIONS

Evaluation of UMRFs in FLs is less effective than in nodules with UC, and its effectiveness decreases parallel to the decrease in percentage of PTCs among malignant neoplasms and to the increase of the percentage of adenomas among benign nodules. The presence of macrocalcifications in such FLs significantly increases the basic risk of malignancy in these nodules.

Malignancy is associated with microcalcification and higher AP/T ratio in ultrasonography, but not with Hashimoto's thyroiditis in histopathology in patients with thyroid nodules evaluated as Bethesda Category III (AUS/FLUS) in cytology

The predictors of malignancy are important for the decision of appropriate management in nodules with atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS). Our aim was to determine the ultrasonographical, clinical, and biochemical predictors of malignancy in these patients. A total of 427 patients with cytologically Bethesda Category III (AUS/FLUS) thyroid nodules were included in this retrospective study. We divided the nodules into two subgroups according to the histopathology as benign and malignant, and compared the preoperative ultrasonographical, clinical, and biochemical findings. In overall, 427 patients with 449 AUS/FLUS nodules who had undergone surgery, the rate of malignancy was 23.4 % (105/449). When evaluated separately, the rate of malignancy was 25.8 % in nodules with AUS (82/318) and 17.6 % in nodules with FLUS (23/131) (p = 0.061). The vast majority of malignant specimens in histopathology consisted of papillary thyroid carcinoma (PTC) (n = 91, 86.7 %). Preoperative ultrasonographic features of 105 malignant nodules in histopathology were compared with the 344 benign nodules in histopathology. Anteroposterior/Transverse (AP/T) ratio was significantly higher in malignant group compared to benign group (p = 0.013). In multiple logistic analysis, we found that higher AP/T ratio and microcalcification were independently associated with malignancy (p < 0.05). The malignancy-associated cut-off value of AP/T ratio at maximum sensitivity and specificity was ≥0.81. We did not find any correlation between malignancy and Hashimoto's thyroiditis in histopathology in multivariate analysis (p > 0.05). In Bethesda Category III nodules with higher AP/T ratio and microcalcification, surgery might be considered as a first therapeutic option instead of repeat fine-needle aspiration biopsy or observation.