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

Serum cholesterol levels are inversely associated with the risk of malignancy in subjects with Bethesda category IV thyroid nodules

INTRODUCTION

Some epidemiological data suggest that there may be an inverse relationship between cholesterol levels and the risk of thyroid cancer in the overall population. The present study was aimed to evaluate the lipid profile specifically in subjects with Bethesda category IV thyroid nodules, and compare whether there were any differences between those with benign and malignant nodules.

METHODS

Single-centre, retrospective study on 204 subjects treated by partial or total thyroidectomy for excision of a Bethesda category IV thyroid nodule, who had undergone a blood lipid profile test in the 12 months prior to surgery. In addition to lipid measures, other demographic, clinical, biochemical and ultrasound data were collected.

RESULTS

Seventy-five subjects (36.8%) were diagnosed with thyroid carcinoma in the definitive histopathological examination. Patients with thyroid cancer had lower levels of total cholesterol, LDL-cholesterol and non-HDL-cholesterol than subjects with benign thyroid diseases. There were no differences in HDL-cholesterol, triglycerides or total cholesterol/HDL-cholesterol ratio. There were no differences either between groups in other clinical, biochemical and ultrasound variables, including the use of lipid-lowering drugs. In multivariate analysis, only LDL-cholesterol was independently associated with malignancy. Subjects with follicular carcinoma showed the lowest cholesterol levels, while those with papillary carcinoma had intermediate values between the group with follicular carcinoma and the group with benign thyroid diseases.

CONCLUSIONS

In subjects with cytologically indeterminate Bethesda category IV thyroid nodules, levels of total cholesterol, non-HDL-cholesterol and, particularly, LDL-cholesterol are lower among those with malignant nodules.

Performance of a multigene genomic classifier and clinical parameters in predicting malignancy in a Southeast Asian cohort of patients with cytologically indeterminate thyroid nodules

BACKGROUND

Most thyroid nodules are benign. It is important to determine the likelihood of malignancy in such nodules to avoid unnecessary surgery. The primary objective of this study was to characterize the genetic landscape and the performance of a multigene genomic classifier in fine-needle aspiration (FNA) biopsies of cytologically indeterminate thyroid nodules in a Southeast Asian cohort. The secondary objective was to assess the predictive contribution of clinical characteristics to thyroid malignancy.

METHODS

This prospective, multicenter, blinded study included 132 patients with 134 nodules. Molecular testing (MT) with ThyroSeq v3 was performed on clinical or ex-vivo FNA samples. Centralized pathology review also was performed.

RESULTS

Of 134 nodules, consisting of 61% Bethesda category III, 20% category IV, and 19% category V cytology, and 56% were histologically malignant. ThyroSeq yielded negative results in 37.3% of all FNA samples and in 42% of Bethesda category III-IV cytology nodules. Most positive samples had RAS-like (41.7%), followed by BRAF-like (22.6%), and high-risk (17.9%) alterations. Compared with North American patients, the authors observed a higher proportion of RAS-like mutations, specifically NRAS, in Bethesda categories III and IV and more BRAF-like mutations in Bethesda category III. The test had sensitivity, specificity, negative predictive value, and positive predictive value of 89.6%, 73.7%, 84.0%, and 82.1%, respectively. The risk of malignancy was predicted by positive MT and high-suspicion ultrasound characteristics according to American Thyroid Association criteria.

CONCLUSIONS

Even in the current Southeast Asian cohort with nodules that had a high pretest cancer probability, MT could lead to potential avoidance of diagnostic surgery in 42% of patients with Bethesda category III-IV nodules. MT positivity was a stronger predictor of malignancy than clinical parameters.

A Comprehensive Approach to the Thyroid Bethesda Category III (AUS) in the Transition Zone Between 2nd Edition and 3rd Edition of The Bethesda System for Reporting Thyroid Cytopathology: Subcategorization, Nuclear Scoring, and More

Significant interobserver variabilities exist for Bethesda category III: atypia of undetermined significance (AUS) of The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). Thus, subcategorization of AUS including AUS "nuclear" and AUS "other" is proposed in the recent 3rd edition of TBSRTC. This study investigated the impact of the nuclear features/architectural features/nuclear score (NS) (3-tiered)/subcategories and subgroups on risk of malignancy (ROM) in thyroid fine-needle aspirations (FNA). 6940 FNAs were evaluated. 1224 (17.6%) cases diagnosed as AUS were reviewed, and 240 patients (initial FNAs of 260 nodules and 240 thyroidectomies) were included. Subcategories and subgroups were defined according to TBSRTC 2nd and 3rd editions. Histological diagnostic groups included nonneoplastic disease, benign neoplasm, low-risk neoplasm, and malignant neoplasm. Overall, ROM was 30.7%. ROM was significantly higher in FNAs with nuclear overlapping (35.5%), nuclear molding (56.9%), irregular contours (42.1%), nuclear grooves (74.1%), chromatin clearing (49.4%), and chromatin margination (57.7%), and these features were independent significant predictors for malignancy. FNAs with NS3 had significantly higher ROM (64.2%). Three-dimensional groups were significantly more frequent in malignant neoplasms (35.7%). ROM was significantly higher in AUS-nuclear subcategory (48.2%) and in AUS-nuclear and architectural subcategory (38.3%). The highest ROM was detected in AUS-nuclear1 subgroup (65.2%). ROM was significantly higher in the group including AUS-nuclear and AUS-nuclear and architectural subcategories, namely "high-risk group" than the group including other subcategories, namely "low-risk group" (42.0%vs 13.9%). In conclusion, subcategorization may not be the end point, and nuclear scoring and evaluation of architectural patterns according to strict criteria may provide data for remodeling of TBSRTC categories.

The risk of malignancy in the atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) category subgroups: a Thai institute experience

INTRODUCTION

This study investigated the rate of reporting and the risk of malignancy (ROM) for atypia of undetermined significance (AUS) subgroups in a Thai population. AUS, which is category III of the Bethesda System for Reporting Thyroid Cytopathology, is a problematic diagnosis for thyroid nodule management because the risks of malignancy are diverse.

MATERIALS AND METHODS

Patients who underwent thyroid fine needle aspirations between January 2015 and December 2019 were included in this retrospective study. Gender, age, and nodule features were described, and all slides were re-evaluated and categorized into 2 subgroups: AUS-Nuclear (including cytology atypia and cytologic and architectural atypia) and AUS-Other (including architectural atypia, oncocytic atypia, and atypia not otherwise specified). The lower and upper limits of ROM were calculated for each subgroup.

RESULTS

Of total, 258 out of 2995 fine needle aspirations (8.6%) were diagnosed as AUS. The patients were predominantly female (88.9%), with a mean age of 54.1 years. The average nodule size was 2.5 cm. Of the 258 AUS patients, 81 (38.9%) had histological correlations. The ROM for the AUS category was 9.1% to 23.5%. The ROM of the AUS-Nuclear and AUS-Other were 11.1% to 27.3% and 2.2% to 6.7%, respectively. Features of pseudonuclear inclusions had the highest ROM (33.3%-42.9%), followed by pale chromatin (28.57%-47.06%).

CONCLUSIONS

Less than ten percent of our interpretations were AUS, which is acceptable in our practice. Cytological atypia harbored the highest ROM. Studies of associations between cytology and histology may aid in improving diagnostic criteria for this population.

Preoperative evaluation of thyroid nodules - Diagnosis and management strategies

Thyroid cancer is the most common endocrine malignancy, with increasing incidence over the past few decades. Fine needle aspiration (FNA) biopsy is the gold standard for preoperative diagnosis of thyroid malignancies. Nevertheless, this method renders indeterminate results in up to 30% of the cases. Therefore, these patients are often referred to unnecessary surgery to establish the diagnosis. To improve the accuracy of preoperative diagnosis, several other ways, such as ultrasonography, elastography, immunohistochemical analysis, genetic testing, and core needle biopsy, have been developed and can be used either in association with or as an alternative to FNA. This review aims to evaluate all these diagnostic tools to determine the most appropriate way of managing thyroid nodules and subsequently improve the selection of cases referred to surgery.

The influence of papillary features on the risk of malignancy in thyroid nodules diagnosed as atypia of undetermined significance or follicular lesion of undetermined significance

BACKGROUND

The objective of this study was to the assess the risk of malignancy in thyroid lesions that were diagnosed as AUS/FLUS when using a novel cytology subclassification system that is based on the presence or absence of papillary features.

METHODS

AUS/FLUS case cytology was re-reviewed and subclassified into minor or major concern groups based upon the absence or presence of papillary features, respectively. The risk of malignancy (ROM) was calculated and compared between the two groups. Inter-pathologist agreement in case subclassification was also measured.

RESULTS

The minor concern group had a 12.6% associated ROM, while the major concern group had a significantly higher ROM (58.4%), (P < 0.001). Based on 108 cases, the inter-pathologist agreement in case subclassification was 79%, and the κ value was 0.47.

CONCLUSIONS

The identification of papillary features significantly increases the ROM in thyroid lesions with an AUS/FLUS diagnosis.

Predictors of Malignancy in Thyroid Nodules Classified as Bethesda Category III

OBJECTIVE

To determine predictors of malignancy in surgically treated Bethesda category III nodules.

METHODS

Patients with surgically treated thyroid nodules classified as Bethesda category III were retrospectively enrolled. The association between clinical/sonographic features and postoperative pathology was evaluated using univariate and multivariate analyses.

RESULTS

A total of 188 nodules from 184 patients were included. The overall malignancy rate was 54.3%. In univariate analysis, male sex, aspect ratio >1, microcalcification, unclear boundary, BRAF^V600E mutation, and nuclear atypia were significantly associated with malignant disease in Bethesda category III nodules. Multivariate analysis confirmed that male sex, aspect ratio >1, microcalcification, and BRAF^V600E mutation were independent predictors of malignant disease.

CONCLUSIONS

Malignant disease was common in Bethesda category III nodules, and surgical treatment was strongly indicated in the presence of male sex, aspect ratio>1, microcalcification, and BRAF^V600E mutation.

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features and the risk of malignancy in thyroid cytology: Data from Singapore

INTRODUCTION

The impact of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) on the risk of malignancy (ROM) in fine-needle aspiration cytology (FNAC) per The Bethesda System for Reporting Thyroid Cytopathology has not been well reported in Singapore.

METHODS

We retrospectively identified 821 thyroid nodules with preoperative FNAC from 788 patients out of 1,279 consecutive thyroidectomies performed between January 2010 and August 2016 in a tertiary general hospital in Singapore. Possible cases of NIFTP were reviewed for reclassification and the impact of NIFTP on ROM was analysed.

RESULTS

The incidence of NIFTP was 1.2% (10 out of 821). If NIFTP is considered benign, ROM in Bethesda I through VI were 8.6%, 3.5%, 26.3%, 20.0%, 87.7%, 97.0% versus 8.6%, 4.2%, 28.1%, 26.7%, 89.2% and 100% if NIFTP is considered malignant. Eight patients with NIFTP had follow-up of 15 to 110 months. One had possible rib metastasis as evidenced by I131 uptake but remained free of structural or biochemical disease during a follow-up period of 110 months. None had lymph node metastasis at presentation, nor locoregional or distant recurrence.

CONCLUSION

Classifying NIFTP as benign decreased ROM in Bethesda II through VI, but the benignity of NIFTP requires more prospective studies to ascertain. The impact of NIFTP on ROM in our institution also appears to be lower than that reported in the Western studies.

Comparison of Korean vs. American Thyroid Imaging Reporting and Data System in Malignancy Risk Assessment of Indeterminate Thyroid Nodules

BACKGROUND

The management of cytologically indeterminate thyroid nodules is challenging for clinicians. This study aimed to compare the diagnostic performance of the Korean Thyroid Imaging Reporting and Data Systems (K-TIRADS) with that of the American College of Radiology (ACR)-TIRADS for predicting the malignancy risk of indeterminate thyroid nodules.

METHODS

Thyroid nodules diagnosed by fine-needle aspiration (FNA) followed by surgery or core needle biopsy at a single referral hospital were enrolled.

RESULTS

Among 200 thyroid nodules, 78 (39.0%) nodules were classified as indeterminate by FNA (Bethesda category III, IV, and V), and 114 (57.0%) nodules were finally diagnosed as malignancy by surgery or core needle biopsy. The area under the curve (AUC) was higher for FNA than for either TIRADS system in all nodules, while all three methods showed similar AUCs for indeterminate nodules. However, for Bethesda category III nodules, applying K-TIRADS 5 significantly increased the risk of malignancy compared to a cytological examination alone (50.0% vs. 26.5%, P=0.028), whereas applying ACR-TIRADS did not lead to a change.

CONCLUSION

K-TIRADS and ACR-TIRADS showed similar diagnostic performance in assessing indeterminate thyroid nodules, and K-TIRADS had beneficial effects for malignancy prediction in Bethesda category III nodules.

A Large Thyroid Fine Needle Aspiration Biopsy Cohort with Long-Term Population-Based Follow-Up

Background: Prior studies evaluating thyroid fine needle aspiration biopsies (FNABs) have limited the calculation of risk of malignancy (ROM) to cytologic specimens with corresponding histologic specimens, and clinical follow-up for those patients who do not undergo immediate surgery has been largely disregarded. Moreover, there is marked variability in how researchers have approached thyroid FNAB statistical analyses. This study addresses the urgent need for information from a large cohort of patients with long-term clinical follow-up to more accurately determine the performance of thyroid FNAB and ROM for each diagnostic category. Methods: A retrospective review of the University of California, San Francisco (UCSF), pathology database for thyroid FNABs from January 1, 1997, to December 31, 2004, was performed. Diagnoses were coded using the 2017 The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC), and patients were matched to both the UCSF cancer registry and California Cancer Registry. Data were analyzed using the Kaplan-Meier method, and stratified by TBSRTC diagnostic category. Kaplan-Meier curves were used to estimate incidence rates of malignancy, stratified by FNAB category. Cox proportional hazards models were used to determine the instantaneous ROM. Results: Initial FNABs from 2207 patients were included. Median follow-up period after the first thyroid FNAB was 13.9 years (range: 10.5-18.4 years). During follow-up, there were 279 confirmed diagnoses of thyroid malignancy. Estimates derived from Kaplan-Meier curves demonstrated that the risk of having a thyroid malignancy was low for nondiagnostic and benign categories, intermediate for atypia of undetermined significance (AUS), follicular lesion of undetermined significance (FLUS), AUS/FLUS combined, and follicular neoplasm, and high for suspicious and malignant categories. A total of 52/1575 false-negative cases (3.2%) were identified. Excluding papillary microcarcinomas, the false-negative rate was 1.5% (23/1575). No patients with a false-negative diagnosis died of thyroid cancer during the follow-up period. Conclusions: Asymptomatic patients with low-risk clinical and radiologic features and initially benign or unsatisfactory biopsy are unlikely to develop thyroid malignancy and highly unlikely to die of thyroid cancer. FNAB is highly accurate in detecting malignancy. Additional studies evaluating similar large data sets after the adoption of TBSRTC and the integration of molecular testing are needed.

Cancer prevalence in the subcategories of the indeterminate class III (AUS/FLUS) of the Bethesda system for thyroid cytology: a meta-analysis

PURPOSE

The indeterminate cytologic report represents a major challenge in the field of thyroid nodule. The indeterminate class III of the Bethesda classification system (i.e., AUS/FLUS) includes a heterogeneous group of subcategories characterized by doubtful nuclear and/or architectural atypia. The study aim was to  conduct a systematic review and meta-analysis to evaluate the rate of malignancy in each subcategory of Bethesda III.

METHODS

PubMed, CENTRAL, and Scopus databases were searched until April 2020. Original articles reporting data on the subcategories of Bethesda III were included. The histological diagnosis was the reference standard to classify true/false negative and true/false positive cases.

RESULTS

The pooled cancer prevalence in each subcategory of Bethesda III was estimated using a random-effects model. Twenty-three papers with 4241 nodules were included. Overall, 1163 (27.4%) were malignant. The cancer rate observed in the subcategories ranged from 15%, in "Hürthle cell aspirates with low risk pattern", to 44%, in "Focal cytologic atypia".

CONCLUSIONS

The overall cancer rate found in the Bethesda III ranged more largely than that originally estimated (10-30%) and varied among any scenarios. These evidence-based data represent a reference for the clinical management of these patients.

Indeterminate thyroid cytology: detecting malignancy using analysis of nuclear images

BACKGROUND

Thyroid nodules diagnosed as 'atypia of undetermined significance/follicular lesion of undetermined significance' (AUS/FLUS) or 'follicular neoplasm/suspected follicular neoplasm' (FN/SFN), according to Bethesda's classification, represent a challenge in clinical practice. Computerized analysis of nuclear images (CANI) could be a useful tool for these cases. Our aim was to evaluate the ability of CANI to correctly classify AUS/FLUS and FN/SFN thyroid nodules for malignancy.

METHODS

We studied 101 nodules cytologically classified as AUS/FLUS (n = 68) or FN/SFN (n = 33) from 97 thyroidectomy patients. Slides with cytological material were submitted for manual selection and analysis of the follicular cell nuclei for morphometric and texture parameters using ImageJ software. The histologically benign and malignant lesions were compared for such parameters which were then evaluated for the capacity to predict malignancy using the classification and regression trees gini model. The intraclass coefficient of correlation was used to evaluate method reproducibility.

RESULTS

In AUS/FLUS nodule analysis, the benign and malignant nodules differed for entropy (P < 0.05), while the FN/SFN nodules differed for fractal analysis, coefficient of variation (CV) of roughness, and CV-entropy (P < 0.05). Considering the AUS/FLUS and FN/SFN nodules separately, it correctly classified 90.0 and 100.0% malignant nodules, with a correct global classification of 94.1 and 97%, respectively. We observed that reproducibility was substantially or nearly complete (0.61-0.93) in 10 of the 12 nuclear parameters evaluated.

CONCLUSION

CANI demonstrated a high capacity for correctly classifying AUS/FLUS and FN/SFN thyroid nodules for malignancy. This could be a useful method to help increase diagnostic accuracy in the indeterminate thyroid cytology.

Subclassification of the Bethesda Category III (AUS/FLUS): A study of thyroid FNA cytology based on ThinPrep slides from the National Cancer Center in China

BACKGROUND

The atypia of an undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) category in the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) is a heterogeneous category, which includes various cell patterns. The subclassification of AUS/FLUS was suggested in the 2017 TBSRTC. However, the risk of malignancy (ROM) associated with different subgroups remains unresolved. Herein, AUS/FLUS aspirates were subclassified, from which the ROM of each subgroup was determined.

METHODS

All cases undergoing fine-needle aspiration (FNA) from July 2013 to December 2018 were reviewed. Of 12,913 thyroid FNAs, 1053 (8.2%) were AUS/FLUS. The slides of 222 patients with AUS/FLUS with surgical follow-up were reviewed and subclassified according to the recommendations of the 2017 TBSRTC. There were 195 aspirates consistently diagnosed as AUS/FLUS and subclassified as cytologic atypia 1 (AUS-C1); cytologic atypia 2 (AUS-C2); architectural atypia (AUS-A); cytologic and architectural atypia (AUS-C&A); Hürthle cell aspirates (AUS-H); atypia, not otherwise specified (AUS-NOS); and atypical lymphoid cells, rule out lymphoma (AUS-L).

RESULTS

Malignancy was identified in 83.3% (185 of 222) of the AUS/FLUS nodules. The AUS-C1 group was the most common (62.1%), followed by the AUS-C&A (12.8%), AUS-C2 (10.8%), AUS-H (6.7%), AUS-NOS (5.6%), AUS-L (1.5%), and AUS-A (0.5%) groups. AUS-C1 had the highest ROM (92.6%) among the groups and varied significantly from that of the AUS-C&A (P = .171), AUS-C2 (P = .001), AUS-H (P = .001), and AUS-NOS (P < .001) groups.

CONCLUSIONS

As a heterogeneous category of TBSRTC, the ROM for AUS/FLUS varies greatly among medical centers. Subclassification of AUS/FLUS might be helpful in identifying nodules with a high ROM in this category and improving the management of such nodules.

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.

Risk Stratification Study of Indeterminate Thyroid Nodules with a next-generation Sequencing Assay with Residual ThinPrep® Material

Objective: The management of indeterminate thyroid nodules is challenging. Molecular testing has emerged as a promising method for stratifying this gray area of fine-needle aspiration (FNA) cytology. Next-generation sequencing (NGS) can be used to test a large variety of genetic changes with very small amounts of nucleic acids obtained from FNA samples.

Methods: Thyroid FNA assays were classified according to the Bethesda System for Reporting Thyroid Cytopathology after routine ThinPrep® slide preparation. Indeterminate nodules with surgical outcomes were assayed with an 18-gene NGS panel with the residual ThinPrep® material, including nodules categorized as atypia of undetermined significance (AUS)/follicular lesions of undetermined significance (FLUS) or follicular neoplasm (FN)/suspicious for a follicular neoplasm (SFN). We evaluated the diagnostic efficacy of the 18-gene panel for thyroid malignancies and potential malignancies and compared it with a well-accepted examination, ThyroSeq v2 testing.

Results: A total of 36 indeterminate nodules were assayed, seven were categorized as AUS/FLUS and 29 as FN/SFN. All of them had adequate DNA for the NGS procedure. When noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) was considered malignant, the risk of malignancy was 71.4% for AUS/FLUS nodules, and 69.0%for FN/SFN nodules. The 18-gene panel showed 72.0% sensitivity, 72.7% specificity, 85.7% positive predictive value (PPV), and 53.3% negative predictive value (NPV) in identifying malignancies and potential malignancies in the indeterminate nodules. Compared with a multicenter report from ThyroSeq v2 testing, 18-gene panel showed a lower NPV (p=0.005), but a higher PPV (p=0.02).

Conclusions: NGS assays are feasible on residual ThinPrep® material, with the advantage of not requiring additional FNA procedure. The 18-gene panel testing can be used as a 'rule in' test for surgical management based on indeterminate nodules and showed a lower NPV but a higher PPV compared to ThyroSeq v2 testing.

Thyroid paraganglioma accompanied by lymph node metastasis or trachea invasion: A case report

Thyroid paraganglioma (TP) is an uncommon neuroendocrine tumor with potential for misdiagnosis. Case 1 (male; 44 years old) presented with hoarseness for 3 months. A 2.5-cm gray nodule in the left thyroid was diagnosed as TP by immunohistochemistry. Lymph node metastasis was confirmed by H&E staining and immunohistochemistry. The patient was followed-up for 3 years without any signs of recurrence or metastasis. Case 2 (female; 39 years old) presented with an asymptomatic but rapidly growing thyroid nodule. The patient underwent thyroidectomy 8 years ago (2008) and was diagnosed with TP postoperatively. The patient was diagnosed with recurrence and exhibited trachea invasion. Thyroidectomy and partial trachea resection were performed. A literature review revealed that 62 other cases of TP have been reported, and most of them exhibited low malignant potential. However, the two cases presented in the current case report exhibited a high malignant potential, accompanied by lymph node metastasis or trachea invasion, and these features imply that the choice of treatment for patients should be based on their different degrees of malignancy.

The diversities in thyroid cytopathology practices among Asian countries using the Bethesda system for reporting thyroid cytopathology

Background

The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) has been adopted and widely used among Asian countries. This study aims to investigate the application of TBSRTC in thyroid cytology practice among Asian countries.

Methods

We searched electronic databases including PubMed and Web of Science from 2010 to 2019. Meta-analysis of proportion and their 95% confidence intervals (CIs) were calculated using the random-effect model. Meta-regression and subgroup analysis were used to search for heterogeneity origins.

Results

We included 42 Asian studies with 84.953 fine-needle aspirations. Among six categories, benign was the most commonly diagnosed category. The resection rate (RR) and risk of malignancy (ROM) were highest in malignant and SM categories, and lowest among benign nodules. Thyroid cytology practice in Asia was characterized by a low RR and high ROM in patients with indeterminate thyroid nodules. There was a significant amount of heterogeneities of TBSRTC outputs (frequency, resection rate, and malignancy risk) among Asian countries. Meta-regression showed that the sources of heterogeneity might stem from the differences in study origin and the application of molecular testing. We highlighted the usefulness of preoperative molecular testing to select patients for surgery.

Conclusions

Our study provided insight regarding thyroid cytology practice among Asian countries. Active surveillance is commonly used in Asian practice resulting in a low RR and high ROM for indeterminate nodules. There are still variations in general thyroid cytology practice in Asia. Future guidelines and consensus regarding the application of TBSRTC in thyroid cytology practice among Asian countries are required.

Malignancy rate of Bethesda category III thyroid nodules according to ultrasound risk stratification system and cytological subtype

The risk of malignancy is considered to be 10% to 30% for cases of thyroid nodules with atypia or follicular lesion of undetermined significance (AUS/FLUS). However, only a minority of patients with AUS/FLUS undergo surgery; therefore, the risk of malignancy might be overestimated due to selection bias. To overcome this problem, we categorized cases of thyroid nodules with AUS/FLUS using the ultrasound risk stratification system (US-RSS) to calculate the malignancy rate and identify the patients most suitable for surgical treatment.In this retrospective observational study, we subcategorized 382 pathologically confirmed thyroid nodules with AUS/FLUS using current US-RSSs (American Thyroid Association, Korean-Thyroid Imaging Report and Data System, American College of Radiology-Thyroid Imaging, Reporting and Data System, European Thyroid Imaging Report and Data System) and calculated the malignancy rate. Additionally, cases of nodules with AUS/FLUS were categorized according to their cytological subtypes, and the malignancy rate was calculated.Current US-RSSs showed good or moderate agreement among them. The overall malignancy rate for thyroid nodules with AUS/FLUS was 38.7%. On categorization of the nodules with AUS/FLUS, the malignancy rates were found to be 60% to 67.5% for the high suspicion category, 32.2-36.6% for the intermediate suspicion category, and 12.4% to 16.3% for the low suspicion category. The malignancy rate for nodules with cytologic atypia was significantly higher than that for nodules with architectural atypia, especially in the intermediate suspicion category.Categorization of thyroid nodules with AUS/FLUS using current US-RSSs helps to determine the optimal course of management of patients, especially when combined with cytological subtype characterization.

Subcategorisation of AUS/FLUS thyroid lesions as per the 2017 Bethesda System for Reporting Thyroid Cytopathology: a retrospective study from a tertiary care centre analysing risk of malignancy (ROM) of the different subcategories

Aims

The 2017 Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) recommends subclassification of atypia of undetermined significance (AUS)/follicular lesion of undetermined significance (FLUS) into six subcategories. The present study evaluates the risk of malignancy (ROM) and risk of neoplasm (RON) among these.

Methods

All thyroid aspirates reported as AUS/FLUS over a 4.5-year period, with available histology, were reviewed and subclassified as per TBSRTC. ROM and RON were calculated and compared.

Results

Of 2554 thyroid aspirates, 281 (11.0%) were AUS/FLUS. Eighty-one with available histology were evaluated. ROM was 51.8%. Cytologic and architectural atypia (AUS-C&A) was the most prevalent (62.9%), followed by Hürthle cell type (19.6%), AUS-A (11.1%), AUS-not otherwise specified (NOS) (7.4%), cytologic atypia (AUS-C) (4.9%) and atypical lymphoid cells (1.2%). Papillary thyroid carcinoma (PTC) and adenomatous goitre (AG) were the most common histological diagnoses (27% each). On histology, AUS-C had 2/4 PTC and 2/4 AG on histology. AUS-A had 4/9 follicular neoplasm (FN) and 2/9 non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) while AUS C&A had 18/51 PTC, 13/51 AG, 11/51 NIFTP and 5/51 FN. ROM and RON were similar across subcategories, ROM was the highest for AUS-C&A (58.8%), AUS-C (50%) and AUS-NOS (50%). NIFTP reclassification as non-malignant reduced ROM to 35.8% (absolute reduction of 16% and a relative decrease of 31%) with the greatest relative decrease seen in AUS-A (50%), followed by AUS-C&A (37%), and none in others.

Conclusions

AUS/FLUS subcategorisation helped to indicate risk for the more likely neoplasm, whether PTC or FN. ROM was the highest for cases with cytological atypia but did not differ significantly across different subcategories. NIFTP changed the ROM of AUS-A and AUS-C&A, since both NIFTP and FN have microfollicles.

Ultrasound characteristics of thyroid nodules facilitate interpretation of the malignant risk of Bethesda system III/IV thyroid nodules and inform therapeutic schedule

Background

This study was designed to explore whether ultrasound of thyroid nodules facilitates the interpretation of the malignant risk of Bethesda III/IV thyroid nodules to inform further therapies.

Methods

We reviewed patient records in which the results of ultrasound‐guided fine‐needle aspiration (US‐FNA) were classified by the Bethesda III/IV in our institution between January 2016 and June 2018. Studies were retrieved from PubMed, Cochrane Central Register of Controlled Trials, ISI Web of Science, Science Direct, Wiley Online Library, EMBASE, China National Knowledge Infrastructure, WanFang, and Chinese VIP. The odds ratio (OR) was used to measure associations between risk factors and thyroid nodule malignancy.

Results

Fifty‐nine cases of Bethesda III/IV with corresponding surgeries were included, and the malignancy risk was 54.2%. Meta‐analysis revealed irregular borders, solitary nodules, hypoechogenicity, microcalcifications, and being taller than wide, all of which increased the malignancy risk of thyroid nodules. Combined ORs for these factors were 4.08 (95% CI: 2.34‐7.14, P < .001), 2.18 (95% CI: 1.39‐3.42, P = .001), 2.02 (95% CI: 1.35‐3.01, P = .001), 3.21 (95% CI: 2.26‐4.56, P < .001), and 4.35 (95% CI: 3.07‐6.15, P < .001), respectively.

Conclusion

As the risk of malignancy for papillary thyroid carcinoma (PTC) is high, when any one of the five ultrasound features of malignancy were confirmed, repeated FNA is recommended to confirm PTC‐type malignancy, even though nodules were Bethesda III/IV classification. However, repeated FNA should be avoided when none of these ultrasound features are identified because repeated FNA does not contribute to identifying non‐PTC type malignancies, such as follicular thyroid carcinoma and poorly differentiated thyroid carcinoma.

Risk of Malignancy According to the Sub-classification of Atypia of Undetermined Significance and Suspicious Follicular Neoplasm Categories in Thyroid Core Needle Biopsies

The objective of this study was to evaluate the risk of malignancy (ROM) associated with atypia of undetermined significance (AUS) and suspicious follicular neoplasm (SFN) core needle biopsy (CNB) categories after further sub-classification. Data from 2267 thyroid nodules evaluated by ultrasound-guided CNB, from January to December 2015, were retrospectively reviewed. AUS nodules (n = 556) were sub-classified as follows: (1) architectural atypia (AUS-A; n = 369, 66.4%), (2) cytologic atypia (AUS-C; n = 35, 6.3%), (3) cytologic/architectural atypia (AUS-C/A; n = 85, 15.3%), or (4) oncocytic atypia (AUS-O; n = 67, 12.1%). SFN nodules (n = 172) were sub-classified as follows: (1) architectural atypia only (SFN-A; n = 110, 64%), (2) cytologic/architectural atypia (SFN-C/A; n = 24, 14%), or (3) oncocytic atypia (SFN-O; n = 38, 22%). Diagnostic surgery was performed in 162 (30.2%) AUS cases and 105 (61%) SFN cases. The ROM of each sub-category was evaluated. The overall ROM was 15.3-52.5% in AUS nodules and 35.5-58.1% in SFN nodules. The ROM was higher in the AUS-C (22.9-88.9%) and AUS-C/A (32.9-90.3%) groups than AUS-A (11.9-40%) and AUS-O (7.5-41.7%). In the SFN category, ROM in the SFN-C/A group was also higher than SFN-A or SFN-O (37.5-75%, 40-57.9%, and 21.1-47.1%, respectively). Our study shows that the ROM was higher in AUS or SFN sub-categories with cytologic atypia than those without cytologic atypia. Because of the heterogeneous nature of AUS and SFN categories, sub-classification may be a more effective approach for risk stratification, allowing optimal management of patients with thyroid nodules.

A Proposal for Separation of Nuclear Atypia and Architectural Atypia in Bethesda Category III (AUS/FLUS) Based on Differing Rates of Thyroid Malignancy

Objectives

Bethesda category III (atypia of undetermined significance/follicular lesion of undetermined significance) includes sparsely cellular specimens with nuclear atypia (3N) and/or architectural atypia (3A). This study investigates whether the two types of atypia have different rates of malignancy (ROMs).

Methods

Cytologic and histologic diagnoses of resected thyroid nodules were recorded. ROM was calculated for all Bethesda categories and for 3N and 3A subcategories. Possible noninvasive follicular thyroid neoplasms with papillary-like nuclear features were reviewed and removed from malignancies, and ROM was recalculated.

Results

A total of 1,396 nodules were included. ROM of 3N (33.3%-26.0%) was higher than 3A (7.7%-5.0%) (P < .0001) and was similar to suspicious for follicular neoplasm (25.0%-20.3%) (P = .3). ROM of 3A approached benign (2.4%-1.5%) (P = .02).

Conclusions

Strong consideration should be given to separating 3N (nuclear atypia with higher risk for papillary thyroid carcinoma) from 3A (architectural atypia with higher chance of being benign) to convey different ROMs.