The atypical thyroid fine-needle aspiration: past, present, and future

Unveiling the Malignancy Risk of Surgically Treated Bethesda III Thyroid Nodules: A 10-Year Retrospective Study Comparing Fine-Needle Aspiration Cytology (FNAC) and Histopathology

Introduction Thyroid malignancy remains a significant global health concern, making the accurate differentiation between benign and malignant thyroid nodules crucial for optimal patient management. Fine-needle aspiration cytology (FNAC) is the gold-standard preoperative diagnostic tool, and The Bethesda System for Reporting Thyroid Cytopathology provides a standardized framework for interpretation. This 10-year retrospective study evaluated the malignancy risk in surgically treated patients with thyroid nodules classified as Bethesda Category III by comparing FNAC findings with histopathological outcomes. Materials and methods This observational retrospective study included patients with thyroid nodules classified as Bethesda Category III treated surgically at Shaukat Khanum Memorial Cancer Hospital and Research Centre (SKMCH & RC) Lahore between January 2014 and January 2024. Data were analyzed using SPSS version 20 (IBM Corp., Armonk, NY, US). Results A total of 44 patients were included in the study, with a mean age of 50.59 years. The majority were female 36 (81.8%) with 8 (18.2%) males. All patients underwent surgery, with 23 (52.3%) undergoing total thyroidectomy and 21 (47.7%) undergoing lobectomy. Final histopathological analysis revealed benign findings in 27 (61.4%) cases and malignancy in 17 (38.6%). Conclusion In our study, benign adenomatous nodules and papillary thyroid carcinoma had equal prevalence. The malignancy rate in Bethesda Category III nodules was 38.6%, higher than the previously reported range of 10% to 30%. This elevated risk may reflect the specialized cancer center setting in which the study was conducted, aligning with similar findings from other cancer centers. These results suggest that Bethesda Category III may carry a higher malignancy risk, warranting reconsideration of current management guidelines.

A Study of Thyroid Fine Needle Aspiration of Follicular Adenoma in the "Atypia of Undetermined Significance" Bethesda Category Using Digital Image Analysis

BACKGROUND

Originally designed for computerized image analysis, ThinPrep is underutilized in that role outside gynecological cytology. It can be used to address the inter/intra-observer variability in the evaluation of thyroid fine needle aspiration (TFNA) biopsy and help pathologists to gain additional insight into thyroid cytomorphology.

METHODS

We designed and validated a feature engineering and supervised machine learning-based digital image analysis method using ImageJ and Python scikit-learn . The method was trained and validated from 400 low power (100x) and 400 high power (400x) images generated from 40 TFNA cases.

RESULT

The area under the curve (AUC) for receiver operating characteristics (ROC) is 0.75 (0.74-0.82) for model based from low-power images and 0.74 (0.69-0.79) for the model based from high-power images. Cytomorphologic features were synthesized using feature engineering and when performed in isolation, they achieved AUC of 0.71 (0.64-0.77) for chromatin, 0.70 (0.64-0.73) for cellularity, 0.65 (0.60-0.69) for cytoarchitecture, 0.57 (0.51-0.61) for nuclear size, and 0.63 (0.57-0.68) for nuclear shape.

CONCLUSION

Our study proves that ThinPrep is an excellent preparation method for digital image analysis of thyroid cytomorphology. It can be used to quantitatively harvest morphologic information for diagnostic purpose.

Malignancy Rates of Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance (AUS/FLUS) Cases: A Tertiary Center Study

Aim

To evaluate the malignancy rates of Atypia of undetermined significance /follicular lesion of undetermined significance (AUS/FLUS) cases in the light of clinical and sonographic features.

Material and Methods

The percentage of AUS/FLUS cases, second fine needle aspiration cytology (FNAC) results, cyto-histopathological correlations and risk of malignancy were analyzed.

Results

113 out of 1461 thyroid FNAC samples (7.7%) were diagnosed as AUS/FLUS and included in the study. Seventy three out of 113 cases (64.6 %) underwent repeat biopsies or surgery. From 45 cases repeat biopsies were taken and 28 had thyroidectomy or lobectomy. There was a significant relation between nodule size and underwent surgery or repeat FNAC (p=0.036). Malignancy rate was 24.6% for cases which had any managements. The malignancy rates were higher in AUS/FLUS cases with cytological atypia (28.8%). After surgery the most common malignancy was papillary thyroid carcinoma, followed by follicular carcinoma.

Conclusion

The risk of malignancy of AUS/FLUS cases is quite high because of the heterogeneity of the group. The sub-classification of this category according to cytological or/and architecture atypia may be more useful in predicting malignancy risk. Further larger studies with ancillary techniques including molecular analysis may be more useful in determining the malignancy risk and appropriate management of this heterogeneous category.

Surgical Outcome and Malignant Risk Factors in Patients With Thyroid Nodule Classified as Bethesda Category III

Background

Thyroid nodules are a very common finding in the general population. Fine-needle aspiration (FNA) has been recommended as the initial test for the evaluation of thyroid nodules. The trend on reporting as atypia of undetermined significance (AUS) has been significantly increased, but the malignant risk is still controversial among different studies. The aim of this study is to investigate the malignancy risk of thyroid nodules reported as Bethesda category III (AUS/FLUS) on initial FNA.

Method

We reviewed 272 papillary thyroid cancer (PTC) patients with suspicious thyroid nodules who underwent fine-needle aspiration and received surgical treatment during 2019 to 2020.

Results

One hundred ten (40.4%) patients were diagnosed with PTC. Multivariate analysis showed that microcalcification (p = 0.037, OR = 2.260, 95% CI: 1.051-4.860), shape (p = 0.003, OR = 4.367, 95% CI: 1.629-11.705), diameters (p = 0.002, OR = 0.278, 95% CI: 0.123-0.631), anti-thyroglobulin antibodies (TGAb) (p = 0.002, OR = 0.150, 95% CI: 0.046-0.494), anti-thyroid peroxidase antibody (A-TPO) (p = 0.009, OR = 4.784, 95% CI: 1.486-15.401), and nodule goiter (p < 0.001, OR = 0.100, 95% CI: 0.046-0.217) were independent malignant risk factors in patients with thyroid nodule classified as Bethesda category III.

Conclusion

In this study, malignant risk factors in patients with thyroid nodule classified as Bethesda category III were significantly associated with preoperative serum TGAb, A-TPO, microcalcification, irregular shape, and nodule diameters. Nodules with malignant factors should be carefully elevated; surgery may be the better option for those patients.

Evaluation of the American College of Radiology Thyroid Imaging, Reporting and Data System (Thyroid imaging reporting) scoring in thyroid Bethesda category on atypia and follicular lesion of uncertain significance patients

OBJECTIVE

Treatment and follow-up are controversial in patients whose thyroid fine needle aspiration biopsy (FNAB) is reported as atypia of undetermined significance and follicular lesion of uncertain significance (AUS/FLUS). We aimed the efficacy of the American College of Radiology Thyroid Imaging, Reporting and Data System (ACR TI-RADS) in preventing unnecessary thyroidectomies in patients with FNA cytology results as AUS/FLUS.

METHODS

In Bolu Abant Izzet Baysal University General Surgery Clinic, case series between 2017 and 2020 were analyzed with thyroid operated. Grouping was made according to the result of postoperative pathology: those with benign results after postoperative pathology were classified as Group 1, and those with malignant results after postoperative pathology were classified as Group 2.

RESULTS

As a result, 66 patients were found to be AUS/FLUS. A total of 28.8% of AUS/FLUS patients have been determined with cancer. In the statistical analysis of the ACR TI-RADS score between the groups, the ACR TI-RADS score in Group 1 patients (3.36) (SD 0.87) was significantly lower than that in Group 2 patients (4.11) (SD 1.04) (p=0.003). The distribution of the ACR TI-RADS scores of the patients in Group 2 was TR2: 2 (15.4%) patients, TR3: 3 (25%) patients, TR4: 5 (16.1%), TR5: 9 (90%) patients, respectively.

CONCLUSION

The ACR TI-RADS score was statistically significant in predicting malignancy in AUS/FLUS patients whose follow-ups and treatments are controversial, and the ACR TI-RADS has a limited role in preventing unnecessary thyroidectomies in patients with AUS/FLUS.

The value of repeating fine-needle aspiration for thyroid nodules

BACKGROUND

Fine-needle aspiration (FNA) is an invaluable technique used in the evaluation of thyroid nodules.

OBJECTIVES

Evaluate the concordance of results for consecutive FNA readings.

DESIGN

Retrospective, descriptive.

SETTINGS

Two tertiary care centers.

METHODS

Demographics were collected along with every FNA result and final pathology results for all patients (aged 9-90 years old) who underwent thyroid surgery from 2010 to 2017. The Bethesda system was used for cytology. Agreement levels were calculated and compared with final pathology.

SAMPLE SIZE

Of 1237 initially included, 1134 had at least one FNA performed with results available for review.

RESULTS

For the 1134 patients, demographic and clinical data were collection and a comparison was made between the three FNA results; the highest agreement was between FNA 2 and 3 (53.6%); however, the kappa value was consistently low for all comparisons, indicating a poor level of agreement overall. Also, the risk of malignancy was higher in this study than in the 2017 Bethesda system for reporting thyroid cytopathology in FNA cytology categories I and II.

CONCLUSION

Repeating FNA biopsies yield different results every time; hence, there is a low level of agreement. The clinical decision should therefore include other important risk factors. Prospective studies could help shed more light on this topic.

LIMITATIONS

Retrospective design.

CONFLICT OF INTEREST

None.

Is Subdivision of Atypia of Undetermined Significance AUS/Follicular Lesion of Undetermined Significance Cases According to Detailed Nuclear Features Vital for Assessing the Risk of Malignancy?

Background:

It has been known that the “atypia of undetermined significance (AUS)/follicular lesion of undetermined significance (FLUS)” category is the most problematic category in Bethesda system due to its highly heterogeneous morphological features. Recently, it has been reported that aspirates including nuclear atypia in the AUS/FLUS category have a higher risk of malignancy.

Aims:

This study aimed to assess each nuclear property in aspirates with cytological atypia and also to determine the relationship with the risk of malignancy.

Material and Methods:

We reviewed 980 AUS/FLUS fine-needle aspirations (FNAs) performed between '2012 and 2019' at a single institution. We classified these aspirates into four groups: AUS-N (nuclear atypia), AUS-A (architectural atypia), AUS-H (Hurthle cell change), and AUS-O (other). Nuclear features were detailed sub-classified; size and shape (enlargement, elongation, and overlapping), membrane irregularities (irregular contours, grooves, pseudoinclusion), and chromatin characteristics (pale chromatin). The estimated risk of malignancy (ROM) was calculated for each subgroup.

Results:

Of 980 AUS/FLUS cases, follow-up histological outcome data were available for 209 cases. Among these cases, the estimated ROM was 27.8%. The ROM were 26.4%, 15.4%, and 22.5% for AUS-N, A, and H, respectively. The most common nuclear findings associated with ROM were nuclear groove (67.9%); irregular contours (76.9%) suspected pseudoinclusion (100%) and overlapping (56%) (P < 0,001). But nuclear findings such as nuclear enlargement, mild pleomorphism, or pale chromatin have a similar ROM as architectural atypia.

Conclusion:

Although it is known that the presence of cytological atypia in an AUS/FLUS nodule increases the estimated risk of malignancy, all nuclear properties are not equally effective in predicting malignancy risk. Emphasizing nuclear atypia details in reports of AUS case may be a more sensitive way to identify nodules with a high risk of malignancy.

Preanalytic variables in quality and quantity of nucleic acids extracted from FNA specimens of thyroid gland nodules collected in CytoLyt: Cellularity and storage time

BACKGROUND

Morphologic and genetic analysis of thyroid nodules may be performed from a single vial. Preanalytic variables that affect nucleic acid extracted from a single vial are evaluated.

METHODS

Thyroid fine-needle aspiration (FNA) specimens collected in CytoLyt were evaluated. A ThinPrep slide was prepared. Extracted nucleic acids were analyzed using Oncomine Comprehensive Panel, version 2, after Ion AmpliSeq library preparation. A pathologist and a cytotechnologist enumerated specimen cellularity.

RESULTS

Fifty-six samples were collected from 55 nodules in 53 patients. Bethesda category correlated with cellularity (P = .01), and storage time (median, 43 days; range, 7-77 days) was longer for specimens in categories II and III than for those in categories IV and VI (P = .01). The mean specimen DNA concentration was 4.5 ng/µL (range, 0-23.8 ng/µL), and 25 (45%) had concentrations >3.3 ng/µL. The mean specimen RNA concentration was 4.8 ng/µL (range, 0-42.4 ng/µL), and 31 (55%) had concentrations >1.4 ng/µL. Nucleic acid quantity increased with epithelial cellularity. Storage time weakly correlated with the quantity of extracted DNA, independent of cellularity, but not extracted RNA. Greater proportions of cell-free DNA and lesser proportions of long, intact RNA fragments were extracted from a subset of samples with longer storage time. Among 15 single nucleotide variants, the median mutant allelic fraction was 15.1%. One false-negative result was identified. Five specimens subsequently determined to harbor a genetic alteration failed quality metrics.

CONCLUSIONS

Cellularity and storage time affect the quantity and quality of nucleic acid extracted from thyroid FNA specimens collected in CytoLyt. Further investigation will serve to quantify the magnitude of such effects and to elucidate other contributing factors.

Can Repeat Biopsies Change the Prognoses of AUS/FLUS Nodule?

OBJECTIVE

Experience with atypia of undetermined significance/follicular lesions of undetermined significance (AUS/FLUS) showed that this category exhibited a marked variability in incidence and malignant outcome in resection specimens. We aimed to determine the utility of repeated fine-needle aspiration biopsies (FNABs) and ultrasonography to determine the malignancy rate in AUS/FLUS nodules.

METHODS

23,587 nodules were biopsied, and 1,288 had at least one AUS/FLUS cytology. Ultrasonographic features including solid hypoechoic status, irregular margins, microcalcifications, nodule taller than wider, or an extrathyroidal extension were also recorded. Nodules for which only 1 FNAB revealed AUS/FLUS cytology were termed Group 1; nodules that underwent 2, 3, and 4 FNABs were termed Groups 2, 3 and 4, respectively. We compared these groups according to malignancy rates.

RESULTS

576 of nodules underwent only 1 FNAB (Group 1); 505, 174, and 33 underwent 2 (Group 2), 3 (Group 3), and 4 FNABs (Group 4), respectively. Fifty-six (30.6%), 45 (27.3%), 18 (30%), and 5 (33.3%) of Groups 1-4 were malignant, respectively. The risk of malignancy was similar in each group (p > 0.05). Suspicious ultrasonographic features were encountered in malignant nodules more than benign nodules (p < 0.05, for each).

CONCLUSION

Repeat biopsy of AUS/FLUS nodules did not enhance the identification of malignancy. Ultrasonographic features may be a better guide for the decision of either surveillance or diagnostic surgery.

UTILITY OF AFIRMA GENE EXPRESSION CLASSIFIER FOR EVALUATION OF INDETERMINATE THYROID NODULES AND CORRELATION WITH ULTRASOUND RISK ASSESSMENT: SINGLE INSTITUTIONAL EXPERIENCE

Objective: We assessed our experience with Afirma gene expression classifier (GEC) combined with sono-graphic risk assessment, using both the American Thyroid Association (ATA) and the Thyroid Imaging Reporting and Data System (TI-RADS) in evaluating indeterminate thyroid nodules. Methods: We identified 98 patients with 101 nodules who had a second fine needle aspiration biopsy (FNA) between January 1, 2014, and September 30, 2017, and sent to Veracyte for cytopathology and subsequent Afirma GEC testing. A second FNA biopsy was performed if the initial cytopathology was either Bethesda III or IV (n = 94) or nondiagnostic (n = 7). We correlated cytopathology, histopathology, and Afirma GEC results with sonographic risk assessment using both the ATA system and TI-RADS. Results: The mean age of the cohort was 57.4 ± 12.3 years; 84% women and 60% white. Repeat FNA was benign in 51 of 101 nodules, and of the remaining 50 nodules, 18 (36%) were GEC-benign and 32 (64%) GEC-suspicious. Eighteen of the 32 GEC-suspicious nodules underwent surgery with the following results: 7 benign (39%), 1 follicular thyroid carcinoma (6%), 6 follicular variant of papillary thyroid cancer (33%), and 4 noninvasive follicular tumor with papillary-like nuclear features (22%). The malignancy rate among the surgical cohort was 39% (without noninvasive follicular tumor with papillary-like nuclear features [NIFTP]) and 61% (with NIFTP) and about 50% and 20% of this group scored in the high suspicion category by ATA and TR5 by TI-RADS, respectively. Conclusion: Afirma GEC was useful in avoiding surgery in one-third of indeterminate nodules and performed similarly to ATA and TI-RADS. However, the use of echogenicity in scoring may underestimate the risk of malignancy in patients with indeterminate nodules. Abbreviations: ATA = American Thyroid Association; AUS = Atypia of Undetermined Significance; FLUS = Follicular Lesion of Undetermined Significance; FN = follicular neoplasm; FNA = fine needle aspiration; FTC = follicular thyroid cancer; FVPTC = follicular variant of papillary thyroid cancer; GEC = Gene Expression Classifier; ND = nondiagnostic; NIFTP = noninvasive follicular tumor with papillary-like nuclear features; TI-RADS = Thyroid Imaging Reporting and Data System; TR = TI-RADS.

Distribution and malignancy risk of six categories of the pathology reporting system for thyroid core-needle biopsy in 1,216 consecutive thyroid nodules

PURPOSE

The purpose of this study was to present the distribution of lesions among the six categories of the pathology reporting system for thyroid core-needle biopsy (CNB), along with the range of malignancy risk of each category based on different diagnostic criteria for benignity in a clinical cohort.

METHODS

For 1,216 consecutive nodules (≥1 cm) of 1,125 patients who underwent CNB at two hospitals, the diagnostic results based on the six categories of thyroid CNB were analyzed. Patients were divided into three groups according to prior fine-needle aspiration (FNA) status: second-line CNB for nodules where prior FNA yielded nondiagnostic or unsatisfactory results (n=57), second-line CNB for nodules with prior FNA results of atypia/follicular lesion of undetermined significance (AUS/FLUS) (n=303), and first-line CNB (n=856).

RESULTS

The proportion of nodules in each CNB category and the range of the malignancy rate for each category was as follows, in order from category I to VI: 1.8%, 23.1%-75.0%; 57.9%, 0.7%-16.7%; 16.0%, 13.2%-46.7%; 8.8%, 53.8%-56.8%; 2.0%, 100%; and 13.5%, 100%. First-line CNB was associated with a higher rate of conclusive diagnoses (category II, IV, or VI) (725 of 856, 84.7%) than second-line CNB with prior nondiagnostic or AUS/FLUS FNA results (241 of 360, 66.9%; P<0.001).

CONCLUSION

The overall distribution of nodules across the six categories of thyroid CNB and the ranges of malignancy risk for those categories were presented in a clinical cohort. First-line CNB tended to produce a higher rate of conclusive results than second-line CNB with prior inconclusive FNA results.

2019 Practice guidelines for thyroid core needle biopsy: a report of the Clinical Practice Guidelines Development Committee of the Korean Thyroid Association

Ultrasound-guided core needle biopsy (CNB) has been increasingly used for the pre-operative diagnosis of thyroid nodules. Since the Korean Society of the Thyroid Radiology published the ‘Consensus Statement and Recommendations for Thyroid CNB’ in 2017 and the Korean Endocrine Pathology Thyroid CNB Study Group published ‘Pathology Reporting of Thyroid Core Needle Biopsy’ in 2015, advances have occurred rapidly not only in the management guidelines for thyroid nodules but also in the diagnostic terminology and classification schemes. The Clinical Practice Guidelines Development Committee of the Korean Thyroid Association (KTA) reviewed publications on thyroid CNB from 1995 to September 2019 and updated the recommendations and statements for the diagnosis and management of thyroid nodules using CNB. Recommendations for the resolution of clinical controversies regarding the use of CNB were based on expert opinion. These practical guidelines include recommendations and statements regarding indications for CNB, patient preparation, CNB technique, biopsy-related complications, biopsy specimen preparation and processing, and pathology interpretation and reporting of thyroid CNB.

Thyroid Bethesda Category AUS/FLUS in Our Microscopes: Three-Year-Experience and Cyto-Histological Correlation

The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) introduced a new category: Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance (AUS/FLUS) comprising of heterogenous lesions with a lesser degree of atypia. Its routine use is a bit controversial. The study cohort included AUS/FLUS thyroid cytopathological diagnoses signed out at Fimlab Laboratories from the period of 1 October 2013 to 31 December 2016. We analyzed all the AUS/FLUS cases, their cytology subclassification, and their cyto-histological correlation, when available. In total, there were 331 AUS/FLUS cases from 252 patients. The mean age was 59.8 years and there were 196 females and 56 males. Repeated AUS/FLUS was diagnosed in 75 (29.8%) cases. Out of 252 patients, 118 (46.8%) were operated on. Sixty-eight were operated on after the first AUS/FLUS diagnosis, 46 after 2 AUS/FLUS diagnoses, and 4 after 3 AUS/FLUS diagnoses. In total, there were 37 (14.7%) malignancies and 40 benign tumors. The risk of malignancy for AUS/FLUS (14.7%) is in agreement with the original TBSRTC risk of malignancy. The risk of neoplasia was 30.6% in our series.

Risk of malignancy in Thyroid "Atypia of undetermined significance/Follicular lesion of undetermined significance" and its subcategories - A 5-year experience

Context

Atypia of undetermined significance/Follicular lesion of undetermined significance [AUS/FLUS] is a heterogeneous category with a wide range of risk of malignancy [ROM] reported in the literature. The Bethesda system for reporting thyroid cytopathology [TBSRTC], 2017 has recommended subcategorization of AUS/FLUS.

Aims

To evaluate the ROM in thyroid nodules categorized as AUS/FLUS, as well as separate ROM for each of the five subcategories.

Settings and Design

Retrospective analytic study.

Methods and Materials

A retrospective audit was conducted for all thyroid fine-needle aspiration cytology (FNAC) from January 2013 to December 2017. Slides for cases with follow-up histopathology were reviewed, classified into the five recommended subcategories, and differential ROM was calculated.

Statistical Analysis Used

z test for comparison of proportions was done to evaluate the difference in ROM among different subcategories of AUS/FLUS. The P value of less than 0.05 was taken as statistically significant.

Results

Total number of thyroid FNACs reported was 1,630, of which 122 were AUS/FLUS (7.5%). Histopathology was available in 49 cases, out of which 18 were malignant (ROM = 36.7%). The risk of malignancy (ROM) for nodules with architectural and cytologic atypia was higher (43.8%) than ROM for nodules with only architectural atypia (16.7%).

Conclusions

The sub-classification of AUS/FLUS into subcategories as recommended by TBSRTC, 2017 may better stratify the malignancy risk and guide future management guidelines.

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.

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.

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.

Cytological Diagnoses Associated with Noninvasive Follicular Thyroid Neoplasms with Papillary-Like Nuclear Features According to the Bethesda System for Reporting Thyroid Cytopathology: A Systematic Review and Meta-Analysis

BACKGROUND

The recent introduction of noninvasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP) in the World Health Organization classification of thyroid tumors has significantly modified the risk of malignancy of cytological diagnoses. In fact, while this tumor was previously classified as a carcinoma (the encapsulated, noninvasive form follicular variant of papillary thyroid carcinoma), it is now considered a neoplasm with low malignant potential. Given that the cytological features of NIFTP are not specific and overlap with other pathologic entities, there is no specific cytological diagnostic category for NIFTP. To obtain more robust information about the cytological findings associated with NIFTP, published articles were systematically reviewed, and a meta-analysis of the data was conducted.

METHODS

The review was conducted according to PRISMA guidelines. A comprehensive literature search of the PubMed/MEDLINE and Scopus databases was conducted using a combination of terms "noninvasive," "encapsulated," "follicular variant," "NIFTP," and "thyroid cancer." The search was updated to June 2018, and references of the retrieved articles were also screened. Only original articles reporting the classification of histologically proven NIFTPs with cytological findings according to The Bethesda System for Reporting Thyroid Cytopathology were eligible for inclusion.

RESULTS

The literature search revealed 117 articles, of which 15 were included in the study. All studies were retrospective. A total of 915 NIFTP cases were retrieved. The incidence of cases cytologically classified according to the Bethesda system was as follows: non-diagnostic 3%, benign 10%, atypia of undetermined significance or follicular lesion of undetermined significance 30%, follicular neoplasm or suspicious for a follicular neoplasm 21%, suspicious for malignancy 24%, and malignant 8%. Mild heterogeneity between the studies was found. Publication bias was absent.

CONCLUSIONS

This meta-analysis shows that the cytological diagnoses associated with NIFTP by fine-needle aspiration cytology includes a wide spectrum of findings. The majority of cases are cytologically indeterminate, and the remainder may be read as non-diagnostic, benign, or malignant. In order to develop an accurate presurgical diagnosis of these cases, further cytological and/or molecular characteristics need to be identified.

A importância da descrição ultrassonográfica padronizada e da punção aspirativa por agulha fina na avaliação de nódulos tireoidianos

Nódulos tireoidianos são muito frequentes, sendo detectáveis pela palpação em cerca de 5% das mulheres. A ultrassonografia e a punção aspirativa por agulha fina (PAAF) são métodos diagnósticos largamente utilizados na propedêutica da doença nodular da tireoide. O objetivo deste estudo foi descrever a utilização da PAAF em pacientes com nódulos tireoidianos submetidos à tireoidectomia. Foram incluídos 20 pacientes, com média de idade de 46±14 anos, (02 homens/18 mulheres), submetidos à PAAF e tireoidectomia em um hospital universitário, entre janeiro/2010 e abril/2016. Apenas 12,5% dos laudos ultrassonográficos descreveram o tamanho dos nódulos em três dimensões e nenhum deles continha todos os itens recomendados para caracterização adequada de um nódulo tireoidiano. De um total de 32 nódulos estudados, 8% constituíram amostra não diagnóstica (categoria Bethesda I). Após tireoidectomia, seis (28%) pacientes apresentaram carcinoma papilífero, sendo dois (33,3%) classificados como Bethesda III e quatro (66,6%) Bethesda V e VI. Observou-se que a falta de padronização dos laudos ultrassonográficos de tireoide pode retardar a investigação diagnóstica e gerar custos elevados para o sistema de saúde. Em contrapartida, o sistema Bethesda está bem consolidado como uma ferramenta para direcionar a conduta frente à doença nodular de tireoide.

Updates in Salivary Gland Fine Needle Aspiration Biopsy: The Use of the Milan System and Ancillary Testing

Salivary gland fine needle aspiration biopsies remain common specimens seen by most cytology services. The diagnostic diversity and overlap between many of the lesions seen with these biopsies impart many challenges for the cytopathologist, rendering most specific diagnoses impossible with cytology alone. Here, the use of the Milan System for the classification of salivary gland fine needle aspiration biopsy FNAB is discussed, together with the potential use of ancillary testing in arriving at definitive diagnoses.

The Bethesda System for Reporting Thyroid Cytopathology Explained for Practitioners: Frequently Asked Questions

BACKGROUND

The recent update of The Bethesda System for Reporting Thyroid Cytology (TBSRTC) is a very important development in the evaluation of thyroid nodules. Clinical experience and scientific literature both show that practitioners performing thyroid fine-needle aspiration are accustomed to basing the clinical management of patients on reports using TBSRTC. Specifically, clinicians are familiar with the percent risk of malignancy corresponding to each TBSRTC diagnostic category (DC), as well as with the respective recommendation for clinical management. However, most clinicians are much less familiar with the specific considerations that lie between a given DC, on the one end, and the respective risk of malignancy and associated management recommendation, on the other end.

SUMMARY

A deeper understanding of the system can enlighten the clinician's thinking about the specific nodule under examination and can guide the decision-making process in a more meaningful way. Such an understanding can only be developed via close two-way communication between cytopathologists and clinicians. Through this type of interaction in the authors' tertiary medical center, recurring issues of particular importance for clinical practice were identified, which are reported here in the form of 16 frequently asked questions posed by the clinician to the cytopathologist.

CONCLUSIONS

For each frequently asked question, an answer is provided based on the literature, the authors' experience, the new version of TBSRTC, and the new World Health Organization classification of tumors of endocrine organs.

The surgery and repeat aspiration outcomes of the atypia of undetermined significance/follicular lesion of undetermined significance category in The Bethesda System for Reporting Thyroid Cytopathology

BACKGROUND/OBJECTIVE

The atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) category is one of six diagnostic categories of The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). In this study, we report the diagnostic distribution of thyroid fine needle aspiration (FNA) cytology and analyze the outcome of AUS/FLUS cases.

METHODS

A total of 29,937 thyroid FNA results, reported between April 2012 and December 2016, were retrieved from the database of a medical center. We reviewed the electronic medical records and analyzed the management of these patients.

RESULTS

Overall frequency of AUS/FLUS is 3.1% in our laboratory, which is at the lower limit of the recommended range. Of these, 891 reports of AUS/FLUS from 770 patients were identified. Out of the 770 patients, 367 had surgical intervention. In these 367 patients, final surgical pathology yielded 204 (55.6%) malignancies, 12 indeterminateness (3.3%), and 151 (41.1%) benignity. Among these surgical patients, 113 (30.8%) had received a repeat FNA of the thyroid before thyroid resection. The difference between the malignancy rates among patients who directly received surgery after the first AUS/FLUS diagnosis (132 of 254, 52.0%) and patients having a repeat FNA before surgery (72 of 113, 63.7%) was not statistically significant.

CONCLUSION

Our results are in agreement with AUS/FLUS diagnoses in less than 7% of specimens, and confirm that it is appropriate to perform either a repeat thyroid FNA or thyroid lobectomy, with the clinical decision being subject to the standardized management protocols of the second edition of TBSRTC in the AUS/FLUS category.

Non-diagnostic thyroid nodules after application of the Bethesda system: a study evaluating the interval for repeat aspiration for non-diagnostic results

Background The non-diagnostic category of the Bethesda system has a low malignancy rate; nevertheless, repeat ultrasonography-guided fine needle aspiration (US-FNA) is recommended with no consensus for follow-up intervals. Purpose To investigate whether a six-month time interval for repeat US-FNA is appropriate for non-diagnostic thyroid nodules after applying the Bethesda system. Material and Methods From January 2010 to January 2014, 322 thyroid nodules ≥10 mm with non-diagnostic results on initial US-FNA with any follow-up with US or US-FNA were included (mean age = 52.2 years ± 12.4). Clinical and US features were compared according to size change (increase, no change, decrease) and follow-up interval (<6 months and ≥6 months after initial US-FNA), and the minimal time interval observed in nodules with size increase on follow-up. The outcome of non-diagnostic nodules according to follow-up interval and size change were evaluated. Results Of the 322 nodules, 13 (4.0%) were malignant and 309 (96.0%) were benign. None of the 82 nodules with decreased size were malignant and 90.2% nodules with decreased size were found after six months. Of 175 nodules with repeat US-FNA, repeat cytology results did not differ significantly between the groups with follow-up US-FNA before and after six months ( P = 0.337). No significant differences were seen in size or extrathyroidal extension among the 13 malignant nodules according to the six-month interval (all P > 0.05), and no lateral lymph node metastasis was present. Conclusion Repeat US-FNA for initially non-diagnostic thyroid nodules can be performed at a six-month interval after initial procedure without tumor progression.

Utility of a formatted pathologic reporting system in thyroid core needle biopsy: A validation study of 1998 consecutive cases

OBJECTIVE

Thyroid core needle biopsy (CNB) is increasingly being used as a tool for evaluating thyroid nodules; thus, standardization of its diagnostic terminology is called for. We aimed to analyse the pathologic reporting system of thyroid CNB based on the recently proposed protocol by the Korean Endocrine Pathology Thyroid Core Needle Biopsy Study Group and evaluate its usefulness.

DESIGN/METHODS

A total of 1998 consecutive cases of thyroid CNBs were reviewed and divided into six categories according to the protocol. Malignancy rate in each category and the diagnostic performance of thyroid CNB were calculated using 705 resected cases.

RESULTS

Thyroid CNB yielded 132 nondiagnostic (6.6%), 791 benign (39.6%), 328 indeterminate (16.4%), 227 follicular neoplasm (11.4%), 69 suspicious for malignancy (3.5%) and 451 malignant lesions (22.6%). In resected specimens, all of the cases designated as suspicious for malignancy and malignant categories in CNB were proven to be true malignant lesions. Lesions diagnosed with follicular neoplasm in CNB were identified as malignant lesions in 57.0%. Malignancy rate was significantly higher in indeterminate lesions with nuclear atypia compared to those with architectural atypia (80.0% vs 28.2%). When CNB diagnoses of indeterminate lesions or higher categories were considered positive, the sensitivity and positive predictive value for final malignant diagnoses were 99.2% and 81.3%, respectively.

CONCLUSIONS

CNB is an accurate method of evaluating thyroid nodules and can serve as an alternative to fine needle aspiration when it is used and reported according to standardized diagnostic categories.

The impact of repeat FNA in non-diagnostic and indeterminate thyroid nodules: A 5-year single-centre experience

INTRODUCTION

FNA is a well-established method for the preoperative diagnosis of thyroid nodules, but limitations still reside among non-diagnostic and indeterminate samples. The objective of the present study was to assess the impact of repeat FNA in thyroid nodules primarily classified as non-diagnostic and indeterminate, with the evaluation of the diagnostic resolution rate after the reassessment of the nodule.

METHODS

We retrospectively collected all cases of thyroid FNA at our institution in the last 5 years that had one or more repeat aspirations of the same nodule, calculating the percentage of samples with change in the diagnostic category. Additional collected data included sex, age and interval between the repeat aspirations.

RESULTS

One hundred and seventy-eight specimens from 167 patients (140 female, 27 male) with a median age of 56 years (range 11-90) were included in the study. Among the 86 cases primarily classified as non-diagnostic, 25 (29.1%) remained in the same category after the first reassessment and only 18 (20.9%) after the second repeat aspiration. Among the 40 indeterminate cases, only 10 (25%) retained their status after the second aspiration, with no change after the third assessment.

CONCLUSION

Repeat aspiration of non-diagnostic and indeterminate thyroid nodules had a positive impact in both groups, with diagnostic resolution rates of 80% and 75%, respectively. The present study therefore endorses the use of such strategy for the initial follow-up of nodules with no definite diagnosis, especially in low-resource centres with limited access to modern molecular technologies.

Role of core needle biopsy as a first-line diagnostic tool for thyroid nodules: a retrospective cohort study

PURPOSE

The purpose of this study was to evaluate the diagnostic efficacy of fine-needle aspiration (FNA), core needle biopsy (CNB), and combined FNA/CNB for the first-line diagnosis of thyroid nodules.

METHODS

A total of 782 consecutive nodules that underwent simultaneous FNA and CNB were analyzed in this study. We compared the rate of inconclusive results and the diagnostic values for malignancy among FNA, CNB, and combined FNA/CNB.

RESULTS

CNB showed a lower rate (10.2%) of inconclusive results than FNA (23.7%) (P&lt;0.001). Combined FNA/CNB showed a lower rate (6.5%) of inconclusive results than FNA (all nodules, P&lt;0.001; macronodules, P&lt;0.001; and micronodules, P&lt;0.001, respectively) or CNB (all nodules, P&lt;0.001; macronodules, P&lt;0.001; and micronodules, P=0.003, respectively). Combined FNA/ CNB and CNB showed significantly higher sensitivity, accuracy, and diagnostic performance for malignancy as defined by criterion 1 (Bethesda category VI) or criterion 2 (Bethesda categories IV/V/VI) than FNA (P&lt;0.001). However, there was no significant difference in the sensitivity, accuracy, or diagnostic performance between combined FNA/CNB and CNB (with criterion 1, P=0.063, P=0.063, and P=0.412, respectively; with criterion 2, P=0.500, P=0.500, and P=0.348, respectively).

CONCLUSION

CNB was found to be more effective than FNA for the diagnosis of thyroid nodules, and its sensitivity and diagnostic performance for malignancy were similar to those of combined FNA/CNB. CNB has the potential to be an effective alternative first-line diagnostic tool for thyroid nodules when performed by an experienced operator.

Atypia of Undetermined Significance in Thyroid Fine Needle Aspirates: a 4-Year Audit of Thy3a Reporting

OBJECTIVE

Thyroid nodules are common within the general population. Cytological analysis of fine needle aspirates (FNAs) of these lesions allows for identification of those that require further surgery. A numerical classification system is in place to streamline reporting. The 3a category is used for lesions that are neither benign nor malignant but show atypia of undetermined significance. We reviewed our use and clinical outcomes of Thy3a over a 4-year period.

METHODS

All thyroid FNAs performed at this institute from January 2012 to December 2015 were identified from our laboratory information system using SNOMED codes. Cytology was correlated with histology.

RESULTS

Of the 1,259 FNAs reported at this institute, Thy3a constituted only 1.2% (n = 16) of all cases, with a malignancy rate of 7%. Five Thy3a cases had a repeat FNA that was reported as Thy2 (benign), 1 as Thy1c (cyst), 1 as Thy3f (follicular lesion), and 1 as Thy5 (malignant). Six cases without repeat FNA were follicular adenomas at resection. Two cases were lost to follow-up. Within all thyroid cytology categories in this 4-year period, we had a false-positive rate of 1.9% and a false-negative rate of 0.3%.

CONCLUSIONS

The Thy3a subclassification has varied diagnostic criteria and lacks reproducibility. Despite the rare use of the Thy3a category at our centre, our diagnostic accuracy remained high. At this time, further Thy3a cohort studies are required to assess the real benefits of this category.

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.

Cytology-Ultrasonography Risk-Stratification Scoring System Based on Fine-Needle Aspiration Cytology and the Korean-Thyroid Imaging Reporting and Data System

BACKGROUND

The malignancy risk of a cytology diagnosis may depend on the ultrasonography (US) patterns of thyroid nodules, and management should be determined by the combined malignancy risk of fine-needle aspiration (FNA) cytology and US patterns. This study was performed to develop a clinically applicable cytology-ultrasonography (CU) scoring system for malignancy risk stratification based on FNA cytology and US patterns, according to the Korean-Thyroid Imaging Reporting and Data System (K-TIRADS).

METHODS

This retrospective Institutional Review Board-approved study included 1651 thyroid nodules (≥1 cm) with final diagnoses. The malignancy risk was assessed of the combined results of FNA cytology and the K-TIRADS for the development of the CU system. The interaction between FNA cytology and US pattern (K-TIRADS) in the malignancy risk of nodules was investigated by using a binominal test.

RESULTS

The malignancy risk of nodules could be stratified into four CU scores (very low risk, <3%; low risk, ≥3%, <30%; high risk, ≥30%, <90%; very high risk, ≥90%). In nodules with non-diagnostic, benign, and atypia of undetermined significance/follicular lesion of undetermined significance cytology results, low-suspicion US pattern (K-TIRADS 3) significantly decreased the malignancy risk of nodules (p = 0.003, 0.013, and 0.027, respectively), and a high-suspicion US pattern (K-TIRADS 5) significantly increased the malignancy risk of nodules (p ≤ 0.001). A Bethesda 1 or 4 cytology result did not significantly change the malignancy risk of any K-TIRADS (p ≥ 0.518 and p ≥ 0.137, respectively). A Bethesda 2 cytology result decreased and a Bethesda 5 or 6 cytology result increased the malignancy risk of K-TIRADS 3, 4, and 5 (p ≤ 0.001). A Bethesda 3 cytology result increased the malignancy risk of K-TIRADS 3 and 4 (p < 0.001 and p = 0.024, respectively).

CONCLUSION

The malignancy risk of thyroid nodules can be stratified by the CU risk-stratification system, based on FNA cytology and the K-TIRADS. The proposed CU scoring system may be helpful in the management of thyroid nodules after FNA.

Proposal for a novel management of indeterminate thyroid nodules on the basis of cytopathological subclasses

Indeterminate thyroid nodules include heterogeneous lesions that could benefit from a differential management. Our aim is to better define the management of the Bethesda System for Reporting Thyroid Cytopathology class III and IV nodules, by identifying cytological subcategories among Bethesda System for Reporting Thyroid Cytopathology class III associated with different clinical risk, by means of ultrasound, repeated FNAB, and BRAFV600E molecular analysis. We also evaluated the outcome of nodules not operated, over a 5-year follow-up. Out of 460 nodules (269 Bethesda System for Reporting Thyroid Cytopathology class III and 191 Bethesda System for Reporting Thyroid Cytopathology class IV), 344 were operated on surgical group and 116 followed-up conservatively (follow-up group). Bethesda System for Reporting Thyroid Cytopathology class III was divided into four subcategories on the basis of cytomorphological features (III-1, III-2, III-3, III-4). Clinical risk was defined on the basis of histological, cytological, and ultrasound data. Malignancy was higher in Bethesda System for Reporting Thyroid Cytopathology class III vs. Bethesda System for Reporting Thyroid Cytopathology class IV (34.4 vs. 26.2 %; p < 0.01). Papillary thyroid carcinoma was the most frequent cancer in each Bethesda System for Reporting Thyroid Cytopathology class (35 %). BRAFV600E diagnostic accuracy was 87 %. Repeated FNAB reclassified as benign nearly 40 % of nodules, selecting patients where surgery could be spared. Significant nodule growth occurred in 13.7 % of nodules, belonging mostly to Bethesda System for Reporting Thyroid Cytopathology class III-2 and Bethesda System for Reporting Thyroid Cytopathology class IV. Overall clinical risk was higher in Bethesda System for Reporting Thyroid Cytopathology III-1, III-4, and IV classes. We propose a differential management of Bethesda System for Reporting Thyroid Cytopathology III and IV classes and related subcategories: surgery may be indicated in Bethesda System for Reporting Thyroid Cytopathology class III-1, III-4, and IV; a conservative follow-up avoiding repeated FNAB may be appropriated in class III-3, while repeated FNAB may be useful in class III-2.

The Use of the Bethesda System for Reporting Thyroid Cytopathology in Korea: A Nationwide Multicenter Survey by the Korean Society of Endocrine Pathologists

Background

The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) has standardized the reporting of thyroid cytology specimens. The objective of the current study was to evaluate the nationwide usage of TBSRTC and assess the malignancy rates in each category of TBSRTC in Korea.

Methods

Questionnaire surveys were used for data collection on the fine needle aspiration (FNA) of thyroid nodules at 74 institutes in 2012. The incidences and follow-up malignancy rates of each category diagnosed from January to December, 2011, in each institute were also collected and analyzed.

Results

Sixty out of 74 institutes answering the surveys reported the results of thyroid FNA in accordance with TBSRTC. The average malignancy rates for resected cases in 15 institutes were as follows: nondiagnostic, 45.6%; benign, 16.5%; atypical of undetermined significance, 68.8%; suspicious for follicular neoplasm (SFN), 30.2%; suspicious for malignancy, 97.5%; malignancy, 99.7%.

Conclusions

More than 80% of Korean institutes were using TBSRTC as of 2012. All malignancy rates other than the SFN and malignancy categories were higher than those reported by other countries. Therefore, the guidelines for treating patients with thyroid nodules in Korea should be revisited based on the malignancy rates reported in this study.

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.

Reproducibility of atypia of undetermined significance/follicular lesion of undetermined significance category using the bethesda system for reporting thyroid cytology when reviewing slides from different institutions: A study of interobserver variability among cytopathologists

BACKGROUND

The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) offers a six-tiered diagnostic scheme for thyroid Fine Needle Aspiration (FNA): Benign, Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance (AUS/FLUS), suspicious for follicular neoplasm, suspicious for malignancy, malignant, and unsatisfactory with an aim to standardize diagnostic criteria. Reported rate of AUS/FLUS category in the literature has varied from 3% to 20.5%.

METHODS

The aim of this study was to assess interobserver variability among cytopathologists to assess reproducibility of the AUS/FLUS category. Seven cytopathologists brought FNA cases (a mixture of atypical and non-atypical FNA diagnosis) diagnosed using TBSRTC from their respective institutions which were reviewed and diagnosed by the participants. The analysis assessed interobserver variability among 7 cytopathologists and determined characteristics on the slides which were associated with concordance to the institutional diagnosis.

RESULTS

Seventy eight of 125 (62.4%) benign cases were classified as benign by the reviewers and 26 (21%) were called AUS/FLUS on review. A third of the AUS/FLUS cases were called benign on review and 28.2% were classified as suspicious for neoplasia/malignancy. Roughly a third each of the suspicious for follicular neoplasm/suspicious for malignancy cases were classified as AUS/FLUS.

DISCUSSION

When pathologists from different institutions shared their slides, concordance was high for specimens with adequate cellularity and those that were clearly benign but thresholds varied for the other indeterminate categories. Most definite categorization of the AUS/FLUS category was seen on review. Diagn. Cytopathol. 2017;45:399-405. © 2017 Wiley Periodicals, Inc.

Malignancy rate in thyroid nodules categorized as atypia of undetermined significance or follicular lesion of undetermined significance - An institutional experience

Introduction:

Atypia of undetermined significance (AUS) or follicular lesion of undetermined significance (FLUS) of Bethesda system for reporting thyroid cytopathology has emerged as most controversial category due to its heterogeneity and inconsistent usage. Initially associated risk of malignancy was estimated to be about 5–15%, but eventually different results have been obtained across institutions due to variable follow-ups and interpretation. The present study was conducted to evaluate the rate of malignancy along with appropriate management in this category.

Materials and Methods:

The study included AUS/FLUS cases diagnosed over period of 4 years on thyroid fine needle aspiration cytology (FNAC). Detailed clinical history and radiological examination were recorded along with follow-ups and management of all cases. Histopathology was available for cases which underwent surgery due to high clinical suspicion, worrisome radiological features or two consecutive AUS/FLUS reports.

Results:

The incidence of AUS/FLUS was 6.4% with repeat FNAC done in 39.6%, immediate surgery in 49.2% and follow-up without intervention in 11.1% cases. The overall malignancy rate was 28.5% with most common malignancy being follicular variant of papillary carcinoma (FVPC). Malignancy rate was more in cases (24.1%) which morphologically showed atypical nuclear features in comparison to architectural atypia.

Conclusion:

AUS/FLUS is associated with higher risk of malignancy than previously anticipated. Surgical intervention may have greater implication than repeat FNAC in appropriate management of this category. Substratification of this category according to nuclear features and architecture may be more useful in predicting malignancy risk and reducing the variability in the group.

Evaluation of thyroid nodules classified as Bethesda category III on FNAC

Background:

The Bethesda (BSRTC) category III has been ascribed a malignancy rate of 5–15%, however, the probability of malignancy remains variable.

Aim:

To evaluate category III with respect to its rate and risk of malignancy and substratify it.

Settings and Design:

Atypia of undetermined significance/Follicular lesion of undetermined significance (AUS/FLUS) percentage, cytohistological correlation, and risk of malignancy were analyzed and substratification was done.

Material and Methods:

Category III cases over a 2-year period were analyzed retrospectively.

Statistical Analysis:

Two-tailed Fisher exact test, with a level of significance set at 0.05, was performed for data analysis.

Results:

Of 1169 thyroid fine needle aspirations (FNAs), 76 (6.5%) were category III. A total of 48 patients had follow up; 24 patients underwent surgery, 12 repeat FNA, and 12 were clinically followed. Repeat FNA cytology was unsatisfactory in 8.3%, benign in 66.7%, AUS in 8.3%, and follicular neoplasm in 16.7%. Of the 24 operated, 8 (33.3%) were malignant (follicular variants of papillary thyroid carcinoma), 5 (20.8%) were follicular adenomas, and 11 (45.8%) were non-neoplastic. Among all AUS/FLUS nodules with follow-up, malignancy was confirmed in 16.7% (8/48) whereas with nodules triaged to surgery only, the malignancy rate was 33.3% (8/24). Substratification into categories of “cannot exclude PTC” and “favor benign” helped detect malignancy better, as 85.7% cases in the first subcategory (P < 0.001) and none (P < 0.02) in the last proved malignant.

Conclusion:

Though the rate of Category III in our study is in accordance to BSRTC, the risk of malignancy in AUS/FLUS nodules is higher. Substratification of AUS/FLUS may help better patient management.

First-Line Use of Core Needle Biopsy for High-Yield Preliminary Diagnosis of Thyroid Nodules

BACKGROUND AND PURPOSE

Although core needle biopsy was introduced as a diagnostic alternative to fine-needle aspiration, the utility and safety of core needle biopsy for thyroid nodules in a large population has yet to be studied comprehensively. We evaluate core needle biopsy yields on a large-scale basis to investigate its potential in the preliminary diagnosis of thyroid nodules.

MATERIALS AND METHODS

Between March 2005 and December 2013, 2448 initially detected thyroid nodules from 2120 consecutive patients who underwent core needle biopsy were retrospectively evaluated. Of these, 72 thyroid nodules from 63 patients were excluded due to prior fine-needle aspiration attempts. The inconclusive and conclusive result rates, diagnostic accuracy, sensitivity, specificity, positive predictive value, negative predictive value, and unnecessary surgery rate of core needle biopsy were evaluated.

RESULTS

With core needle biopsy as the first-line method, the inconclusive result rate was 11.9% (283/2376) and the conclusive result rate was 88.1% (2093/2376). The diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of core needle biopsy for the diagnosis of malignancy were 96.7% (1160/1200), 89.7% (347/387), 100% (813/813), 100% (347/347), and 95.3% (813/853), respectively. There were no major complications and 12 minor complications.

CONCLUSIONS

We have demonstrated that first-line use of core needle biopsy may well improve diagnostic accuracy in thyroid nodules, reducing inconclusive or false-negative results and unnecessary operations. Such benefits underscore the promising role of core needle biopsy in managing thyroid nodules and optimizing related surgical decision-making.

Core-needle biopsy versus repeat fine-needle aspiration for thyroid nodules initially read as atypia/follicular lesion of undetermined significance

BACKGROUND

The purpose of this study was to evaluate the role of core-needle biopsy (CNB) by comparing the results of CNB and repeat fine-needle aspiration (FNA) for thyroid nodules that are initially read as atypia/follicular lesion of undetermined significance (AUS/FLUS) on FNA.

METHODS

Among 2631 initial AUS/FLUS FNA results, 505 consecutive nodules (295 repeat FNAs and 210 CNBs) were retrospectively analyzed. The primary outcome was inconclusive (ie, nondiagnostic or AUS/FLUS). The secondary outcomes included inconclusive results of the subcategory, risk factors for inconclusive results, and diagnostic performance.

RESULTS

CNB demonstrated significantly fewer inconclusive results than repeat FNA for the overall nodules (40.9% vs 63%; p < .001). Repeat FNA and group FLUS were significant risk factors for inconclusive results (odds ratio = 1.92; p =.001 and odds ratio = 2.08; p <.001, respectively). All diagnostic performances using CNB were higher than repeat FNAs.

CONCLUSION

CNB is more useful than repeat FNAs for reducing inconclusive results and improving the diagnostic performance of thyroid nodules with initial AUS/FLUS FNA results. © 2016 Wiley Periodicals, Inc. Head Neck 39: 361-369, 2017.

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.

The 5-tiered categorization system for reporting cytology is sufficient for management of patients with thyroid nodules compared to the 6-tiered Bethesda system

To analyze whether the 5-tiered categorization system without the atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS) category is sufficient compared to the 6-tiered Bethesda system. This IRB-approved retrospective study was waived informed consent. The pre-Bethesda period was from March 2008 to December 2008 and the Bethesda period was from January 2012 to January 2013. Of 4677 nodules ≥10 mm with initial ultrasonography-guided fine-needle aspiration, 2553 nodules were from the pre-Bethesda period and 1754 nodules were from the Bethesda period. The utilization and malignancy rates of each category were compared between the two periods. The utilization rate of the benign category decreased from 67.7 % in the pre-Bethesda period to 60.0 % in the Bethesda period (p = 0.001). In the pre-Bethesda period, the malignancy rates of the non-diagnostic, benign, suspicious follicular neoplasm/Hürthle cell neoplasm, suspicious for malignancy, and malignancy categories were 3.8, 1.9, 25, 78.8, and 99.7 %, respectively. The malignancy rate of the benign category decreased from 1.9 to 0.3 % after the Bethesda system (p < 0.001). The utilization and malignancy rates of the AUS/FLUS category were 7 and 22.8 %. When the AUS/FLUS category was included in the benign category, the malignancy rate became 2.6 % which was not significantly different from 1.9 % in the pre-Bethesda period (p = 0.189). The malignancy rates of other categories were not significantly different. The 5-tiered categorization system without the AUS/FLUS category for reporting cytology was sufficient for management of patients with thyroid nodules compared to the 6-tiered categorization of the Bethesda system.

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

OBJECTIVE

To evaluate the clinical significance and compare the imaging features according to the Thyroid Image Reporting and Data System (TIRADS) between atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) subcategories.

DESIGN & PATIENTS

A total of 192 thyroid nodules in 188 patients (mean age: 50·2 ± 11·8 years) that had been initially diagnosed as AUS/FLUS on US-guided fine needle aspiration (US-FNA) were included. One cytopathologist retrospectively reviewed the cytology slides, subcategorizing cytology results into AUS and FLUS. A TIRADS category was assigned to each thyroid nodule according to the number of suspicious US features. Clinical, US features and malignancy rates were compared between the two subcategories.

RESULTS

Of the 192 AUS/FLUS lesions, 149 (77·6%) were subcategorized as AUS and 43 (22·4%) as FLUS. Of the 192 AUS/FLUS nodules, 82 (42·7%) were malignant. The malignancy rates between AUS and FLUS subcategories were not significantly different, 45·6% to 32·6%, respectively (P = 0·127). When applying TIRADS, significant differences were seen in TIRADS category between benign and malignant nodules in the AUS subcategory (P < 0·001), but not in the FLUS subcategory (P = 0·414). The malignancy rates in TIRADS categories 3, 4a, 4b, 4c and 5 were 15·4%, 22·2%, 33·3%, 57·1% and 80·0% (P < 0·001) in AUS nodules and 40·0%, 50·0%, 23·5%, 22·2% and 0·0% (P = 0·414) in FLUS nodules, respectively.

CONCLUSION

Suspicious US features are useful in predicting malignancy among AUS subcategories but not in FLUS subcategories. Subcategorization into AUS and FLUS cytology may be helpful in deciding upon treatment or management of thyroid nodules.

Subcategorization of Bethesda System Category III by Ultrasonography

BACKGROUND

Bethesda System category III (atypia of undetermined significance/follicular lesion of undetermined significance [AUS/FLUS]) creates a dilemma because of heterogeneity. The aim of this study was to assess whether ultrasonography (US) contributes to differentiating AUS from FLUS and may suggest characteristics of malignancy within category III.

METHODS

From April 2011 to April 2012, 433 thyroid nodules that had been interpreted as nuclear atypia (AUS group; n = 322) or microfollicular architecture (FLUS group; n = 111) were included in the retrospective study. Final diagnoses were acquired in 327 nodules after surgery and clinico-radiological follow-up. The AUS group and FLUS group were compared in terms of US features (composition, echogenicity, margin, shape, and calcifications), US diagnosis (probably benign, malignant), malignancy rate, and final malignant histology.

RESULTS

In univariate and multivariate analysis, the AUS group more frequently had non-circumscribed margins, taller-than-wide shape, and an US diagnosis suggestive for malignancy than the FLUS group did. The risk of malignancy was significantly higher in the AUS group than it was in the FLUS group (51.0% vs.8.1%; p < 0.001). There was a significant difference in the presence of a BRAF mutation between the AUS group and the FLUS group (47.6% vs. 4.2%; p < 0.001). Of the patients with malignancy, papillary thyroid carcinoma was found more frequently in the AUS group than in the FLUS group (97.7% vs. 66.7%; p = 0.004). The incidence of follicular thyroid carcinoma was significantly higher in the FLUS group than it was in the AUS group (33.3% vs.1.6%; p = 0.004).

CONCLUSION

Bethesda System category III subcategorization into AUS and FLUS can be supported by US features. In Bethesda III nodules, US features may further help in predicting a malignant histology.

Diagnostic value of BRAF (V600E)-mutation analysis in fine-needle aspiration of thyroid nodules: a meta-analysis

Fine-needle aspiration (FNA) is a reliable method for preoperative diagnosis of thyroid nodules; however, about 10%–40% nodules are classified as indeterminate. The BRAF^V600E mutation is the most promising marker for thyroid FNA. This meta-analysis was conducted to investigate the diagnostic value of BRAF^V600E analysis in thyroid FNA, especially the indeterminate cases. Systematic searches were performed in PubMed, Web of Science, Scopus, Ovid, Elsevier, and the Cochrane Library databases for relevant studies prior to June 2015, and a total of 88 studies were ultimately included in this meta-analysis. Compared with FNA cytology, the synergism of BRAF^V600E testing increased the diagnostic sensitivity from 81.4% to 87.4% and decreased the false-negative rate from 8% to 5.2%. In the indeterminate group, the mutation rate of BRAF^V600E was 23% and varied in different subcategories (43.2% in suspicious for malignant cells [SMC], 13.77% in atypia of undetermined significance/follicular lesion of undetermined significance [AUS/FLUS], and 4.43% in follicular neoplasm/suspicious for follicular neoplasm [FN/SFN]). The sensitivity of BRAF^V600E analysis was higher in SMC than that in AUS/FLUS and FN/SFN cases (59.4% vs 40.1% vs 19.5% respectively), while specificity was opposite (86.1% vs 99.5% vs 99.7% respectively). The areas under the summary receiver-operating characteristic curve also confirmed the diagnostic value of BRAF^V600E testing in SMC and AUS/FLUS rather than FN/SFN cases. Therefore, BRAF^V600E analysis can improve the diagnostic accuracy of thyroid FNA, especially indeterminate cases classified as SMC, and select malignancy to guide the extent of surgery.

Ultrasonography Diagnosis and Imaging-Based Management of Thyroid Nodules: Revised Korean Society of Thyroid Radiology Consensus Statement and Recommendations

The rate of detection of thyroid nodules and carcinomas has increased with the widespread use of ultrasonography (US), which is the mainstay for the detection and risk stratification of thyroid nodules as well as for providing guidance for their biopsy and nonsurgical treatment. The Korean Society of Thyroid Radiology (KSThR) published their first recommendations for the US-based diagnosis and management of thyroid nodules in 2011. These recommendations have been used as the standard guidelines for the past several years in Korea. Lately, the application of US has been further emphasized for the personalized management of patients with thyroid nodules. The Task Force on Thyroid Nodules of the KSThR has revised the recommendations for the ultrasound diagnosis and imaging-based management of thyroid nodules. The review and recommendations in this report have been based on a comprehensive analysis of the current literature and the consensus of experts.

Cytopathologic diagnosis of fine needle aspiration biopsies of thyroid nodules

Fine-needle aspiration (FNA) cytology is an important diagnostic tool in patients with thyroid lesions. Several systems have been proposed for the cyropathologic diagnosis of the thyroid nodules. However cases with indeterminate cytological findings still remain a matter of debate. In this review we analyze all literature regarding Thyroid Cytopathology Reporting systems trying to identify the most suitable methodology to use in clinical practice for the preoperative diagnosis of thyroid nodules. A review of the English literature was conducted, and data were analyzed and summarized and integrated from the authors’ perspective. The main purpose of thyroid FNA is to identify patients with higher risk for malignancy, and to prevent unnecessary surgeries for benign conditions. The Bethesda System for Reporting Thyroid Cytopathology is the most widely used system for the diagnosis of thyroid FNA specimens. This system also contains guidelines for the diagnosis and treatment of indeterminate or suspicious for malignancy cases. In conclusion, patients who require repeated FNAs for indeterminate diagnoses will be resolved by repeat FNA in a percentage of 72%-80%.

Malignancy risk of oncocytic changes in thyroid nodules: who should we offer surgery to?

Background Oncocytic (Hürthle) cell in fine-needle aspiration biopsy (FNAB) remains challenging for surgeons. Surgical treatment is recommended for oncocytic change in FNAB, since it can sometimes be a struggle to determine the nature of thyroid nodules. We aimed to investigate the clinical significance of oncocytic changes in FNAB in terms of management of patients. Methods The FNAB samples of 172 patients with thyroid nodules were reviewed. Of these, 39 patients with cytologic findings of oncocytic changes on FNAB [POC: predominance of oncocytic cells; SFON-H: suspicious for follicular or oncocytic neoplasm (Hürthle cell type), SM-O: suspicious for malignancy-papillary or follicular carcinoma; oncocytic variant)] were included. Results FNAB demonstrated POC in 14 (35.8%), SFON-H in 15 (38.4%), and SM-O in 10 (25.6%) patients. The overall malignancy rate was 35.8% (n = 14). Clinical and laboratory data were not found to be associated with thyroid cancer while nodule size was significantly higher in patients with thyroid malignancy (15.2 versus 23.3 mm, p = 0.032). Regarding FNAB results including oncocytic changes, the rate of malignancy was significantly different and almost three-fold higher in nodules classified as SFON-H and SM-O [48% versus 14.2% with POC, p = 0.044]. Besides, there was a positive correlation between SFON-H and SM-O cytology and malignancy (p = 0.036, r = 0.337). Conclusions It is hard to discern the significance of oncocytic changes in FNAB report and to determine an optimal approach as a surgeon. We recommend surgery for the patients with an FNAB showing SFON-H and SM-O whereas POC should be better to be followed-up.

Pathobiology of MicroRNAs and Their Emerging Role in Thyroid Fine-Needle Aspiration

OBJECTIVE

MicroRNAs (miRs) are noncoding, single-stranded regulatory RNA molecules involved in the posttranscriptional regulation of gene expression. They control the development and maintenance of the diverse cellular processes including proliferation, differentiation, motility and apoptosis. Expression of miRs is tissue-specific and each alteration of the tissue miR profile is associated with a distinct disease status.

STUDY DESIGN

We reviewed the literature on the expression of miRs in thyroid tumors, focusing on methodology and diagnostic and prognostic output. Separately, we analyzed 11 studies on miR profiles in thyroid cytological material.

RESULTS

Numerous studies have evaluated the miR profiles of thyroid tumors in an attempt to find a possible diagnostic and prognostic role. Both downregulation and upregulation of numerous miRs was found, but differences between the surgical pathology specimens and corresponding fine-needle aspirates in the expression of the same miRs were also reported.

CONCLUSIONS

The results from surgically resected material cannot be extrapolated into preoperative use without validation. For diagnostic use, the strong overlap between follicular adenoma and follicular carcinoma miR profiles is challenging. In summary, miR-221 and miR-222 are consistently upregulated in different types of thyroid carcinomas and might be used as markers of malignancy.

Cytological diagnosis of pediatric thyroid nodule in perspective of the Bethesda System for Reporting Thyroid Cytopathology

Background:

Thyroid nodule is one of the most common endocrinopathies occurring children and adolescents. Though thyroid nodule is rare in the pediatric age group, the rate of malignancy is much higher in this age group compared to adult population.

Aim:

The objective is to study the application of The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) in pediatric patients and compare the findings with histology.

Materials and Methods:

A total of 218 cases younger than 18 years were studied in a 4-year period from August 2010 to July 2014. The smears were categorized according to TBSRTC into six categories — Nondiagnostic, benign, atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS), suspicious for follicular neoplasm (SFN), suspicious for malignancy (SM), and malignancy.

Results:

Out of 218 cases, 33 were males and 185 were females. Histological follow-up was available in 44 cases. The diagnosis according to TBSRTC included 12 (5.5%) nondiagnostic, 151 (69.26%) benign, 23 (10.5%) AUS/FLUS, 18 (8.2%) SFN, 5 (2.3%) SM, and 9 (4.1%) malignancy cases. On histological follow-up, the rate of malignancy in each category was 0%, 0%, 8.3%, 10% 100%, and 100%, respectively.

Conclusion:

The study demonstrates that TBSRTC in pediatric thyroid nodule is as sensitive and specific as in adults, especially with 100% accuracy in the diagnosis of benign and malignant categories.

Diagnostic Thyroidectomy May Be Preferable in Patients With Suspicious Ultrasonography Features After Cytopathology Diagnosis of AUS/FLUS in the Bethesda System

Atypia/follicular lesion of undetermined significance (AUS/FLUS) is a new category in the Bethesda System for Reporting Thyroid Cytopathology (BSRTC) for which repeat fine-needle aspiration cytology (FNAC) is recommended. The aim of this study was to identify specific ultrasonography and clinical predictors of malignancy in a subset of thyroid nodules associated with cytology diagnoses of AUS/FLUS.Between January 2011 and December 2102, 5440 patients underwent thyroid surgery at our institution. Of these, 213 patients were diagnosed AUS/FLUS at the preoperative cytopathology diagnosis. The frequency of FNAC and ultrasonography images was compared between patients with cancerous and benign tumors based on their final pathology.Of the 213 patients, 158 (74.2%) were diagnosed with thyroid carcinoma in their final pathology reports. In univariate and multivariate analyses, the frequency of FNAC was not significantly correlated with the cancer diagnosis. Hypoechogenicity (odds ratio 2.521, P = 0.007) and microcalcification (odds ratio 3.247, P = 0.005) were statistically correlated with cancer risk.Although AUS/FLUS in cytopathology is recommended for repeating FNAC in BSRTC, we proposed that thyroid nodules with ultrasonography findings that suggest the possibility of cancer should undergo thyroidectomy with diagnostic intent.