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Purpose: Although the thyroid isthmus seems like a rudimentary structure that connects bilateral lobes, it is an undiscovered area that needs to be explored. Currently, the data is evolving that the increase in the risk of malignancy is higher in the isthmic nodules, and extrathyroidal extensions and lymph node metastases are more common in isthmic-derived malignant thyroid nodules. Therefore, we aimed to compare the malignancy rate of isthmic and lobar nodules, the ultrasonographic features of isthmic and lobar nodules, and presence of lymph node metastases, distant metastases, and extrathyroidal invasions in malignant isthmic nodules., Methods: In this retrospective study, we enrolled patients between the ages of 18-80 years, who had thyroid nodule/nodules cytology and/or pathology results from January 2009 to November 2022. 9504 nodules were selected for the analysis of US findings, cytopathology results, and malignancy rates., Results: A mean ± SD age of 55.3 ± 13.0 years with a female to male ratio of [7618 (80.2%)/1886(19.8%)] were included in the study. 962 of the nodules were at isthmic localization; whereas 8542 nodules were at lobar localization. 1188 nodules were resulted as malignant from histopathological evaluation. Of the 1188 malignant nodules, 986 nodules were (83.0%) PTC, 114 nodules (9.6%) were FTC, 55 nodules were (4.6%) MTC, 16 nodules 1.3% were Hurtle cell carcinoma, 8 nodules (0.7%) were anaplastic thyroid carcinoma, and 9 nodules (0.8%) were thyroid tumors of uncertain malignant potential (TT-UMP). 156 of the malignant nodules (13.1%) were located in the isthmus, whereas the majority of the malignant nodules (n = 1032, 86.9%) were located at the lobar parts (right or left) of the thyroid. When the metastasis patterns of isthmic and lobar thyroid cancers were examined, no significant relationship was found between isthmic and lobar cancers in terms of capsule invasion (p = 0.435), muscle invasion (p = 0.294), and lymph node metastasis (p = 0.633). A significant relation was found between nodule localization (isthmus-upper-middle and lower lobes) and malignancy (p < 0.001). In our logistic regression analysis, isthmic and upper pole nodule localizations, age and TI-RADS were evaluated as independent risk factors for malignancy (p < 0.001 for all factors)., Conclusion: We recommend nodule localization has to be considered an additional risk factor when performing a Fine Needle Aspiration Biopsy for the increased malignancy risk in this localization., (© 2024. The Author(s).)

Purpose: Ultrasound-guided fine-needle aspiration biopsy (UG-FNAB) was implemented in Qilu Hospital of Shandong University in 2015 as a preoperative diagnostic method for thyroid surgery. BRAF p.V600E genetic testing was implemented in 2019. This study evaluated the impact of these two tests on the malignancy rate in patients undergoing thyroidectomy., Methods: A total of 19,496 patients were included in the study. We retrospectively collected data from patients undergoing thyroid surgery in the Hospital Information System (HIS) of Qilu Hospital of Shandong University from January 2012 to December 2021. Meanwhile, data of FNAB, UG-FNAB, and BRAF p.V600E genetic testing were collected. Differences in means among groups were analyzed via one-way ANOVA, and differences in frequencies were analyzed via Pearson's chi-squared test., Results: In this study, the 10-year period was divided into three stages, with the implementation of UG-FNAB in 2015 and that of BRAF p.V600E genetic testing in 2019 as dividing lines. The malignancy rate in thyroid surgery increased significantly during these three stages (48.06% vs. 73.47% vs. 88.17%; P < 0.001). In the same period (May 2019 to December 2021), the malignancy rate in thyroid surgery was significantly different between the Non-FNAB, UG-FNAB, and UG-FNAB-BRAF groups (78.87% vs. 95.63% vs. 98.32%; P < 0.001)., Conclusions: The successful implementation of UG-FNAB and BRAF p.V600E genetic testing improved the malignancy rate in thyroid surgery and reduced unnecessary diagnostic surgery for benign and marginal lesions. It can, therefore, provide a clinical reference for other hospitals., (© 2022. The Author(s).)

Background: Thyroid nodules are stratified through fine-needle aspiration (FNA) and are often categorized using The Bethesda System for Reporting Thyroid Cytopathology, which estimates the risk of malignancy for six cytopathological categories. The atypia of undetermined significance (AUS) and follicular lesion of undetermined significance (FLUS) categories have varying malignancy rates reported in the literature which can range from 6 to 72.9%. Due to this heterogeneity, we assessed the malignancy rate and effectiveness of repeat FNA (rFNA) for AUS/FLUS thyroid cytopathology at our institution., Methods: Electronic health records of patients with AUS/FLUS thyroid cytopathology on FNA at our center since the implementation of the Bethesda System on May 1, 2014-December 31, 2019 were retrospectively reviewed. Patient demographics, treatment pathway, and pathology results were collected. The treatment pathway of the nodules, the rFNA results, and the malignant histopathology results were reported. Malignancy rates were calculated as an upper and lower limit estimate., Results: This study described 182 AUS/FLUS thyroid nodules from 177 patients. In total, 24 thyroid nodules were deemed malignant upon histopathology, yielding a final malignancy rate of 13.2-25.3%. All of the malignancies were variants of papillary thyroid carcinoma. The malignancy rate of the nodules which underwent resection without rFNA (21.5%) was lower than the malignancy rate of the nodules which underwent resection after rFNA (43.8%). 45.5% of the rFNA results were re-classified into more definitive categories., Conclusion: The malignancy rate of AUS/FLUS thyroid cytopathology at our center is in line with the risk of malignancy stated by the 2017 Bethesda System. However, our malignancy rate is lower than some other Canadian centers and approximately half of our rFNAs were re-classified, highlighting the importance of establishing center-specific malignancy and rFNA re-classification rates to guide treatment decisions., (© 2021. The Author(s).)

Introduction: The Bethesda System for Reporting Thyroid Cytopathology was developed in 2007 to facilitate an accurate, reproducible communication of thyroid fine-needle aspiration (FNA) interpretations between clinicians and cytopathologists and to serve as a guide for treatment. Based on large patient series, the system details the risk of malignancy for each category as well as a suggested management for each FNA result. Though this system has been widely adopted, there are only few studies to determine whether results are applicable for Israel., Methods: A multicenter, retrospective analysis of medical charts of all patients who underwent thyroid surgery between January 1st, 2012 and December 31st, 2016 in four medical centers in Israel was performed. Data was analyzed for the overall risk of malignancy for the Bethesda system groups as well as comparison between the different laboratories performing the test., Results: Records of 810 thyroidectomies in which preoperative cytological reports and final pathology were available and reviewed. The malignancy rates according to the Bethesda groups' I-VI for our cohort were: 27.8%, 17.6%, 41.4%, 41.4%, 86.9%, and 98.1% respectively. Similar results were seen when results were analyzed according to the different laboratories performing the tests., Conclusions: Post-surgical review of all Bethesda groups had higher malignancy rates than those reported in the original report. These results indicate a difference in the malignancy rates for the different Bethesda system groups in Israel compared to those reported. Physicians are encouraged to use data validated for their own country or patients' community in addition to published values., Competing Interests: Declaration of competing interest All authors have nothing to declare. There's no financial/personal interest or belief that could affect their objectivity., (Copyright © 2021 Elsevier Ltd, BASO ~ The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.)

Background: Fine-needle aspiration cytology (FNAC) has become a well-established modality in the diagnosis, staging and follow-up of thyroid nodules. FNAC outcomes are routinely classified using the Bethesda System for Reporting Thyroid Cytopathology (BSRTC), facilitating appropriate clinical management. Bethesda categories III and IV encompass varying risks of malignancy. This retrospective study established a possible association between these cytological categories and malignancy rates in patients treated at a single institution., Methods: Over a 6-year period, 11,627 FNAC procedures were performed on thyroid nodules. Of these, 814 (59.63%) patients were submitted to thyroidectomy. The nodules of 108 patients were classified as Bethesda category III and 47 patients as Bethesda category IV. Patient data were reviewed to establish a correlation between the FNAC results and the final histopathological analyses., Results: The rates of malignancy among patients who underwent surgery were 25% for category III and 27.6% for category IV, with no significant differences between categories (p = 0.67). The pathological parameters of malignant nodules, namely tumour type, size, encapsulation, invasion into the thyroid capsule, extrathyroidal extension and lymphovascular invasion did not significantly differ between the groups (p > 0.05)., Conclusions: This paper provides a more precise correlation of malignancy rates with thyroid nodules classified as Bethesda categories III and IV, as our findings are comparable to the literature, giving malignancy rates ranging from 10 to 30% for category III and 25-40% for category IV. Use of the BSRTC is heterogeneous across institutions, and there is some degree of subjectivity in the distinction between categories III and IV; therefore, it is crucial to estimate the rates of malignancy at each institution. Molecular assays are of increasing importance in determining the need for surgical intervention for thyroid lesions. Gene expression assays using FNAC material may demonstrate a high predictive value for cytologically indeterminate thyroid nodules diagnosed as Bethesda classes III and IV.

Introduction: The rates of atypia of undetermined significance (AUS) by fine-needle aspiration (FNA) and malignant outcomes have been estimated at < 7% and 5-15%, respectively. Initial AUS diagnosis is followed up clinically with serial ultrasounds, repeat FNA, molecular testing, or direct surgery. We investigated the incidence, follow-up modalities, and final outcomes of AUS in Newfoundland., Methods: All cases of AUS diagnosed at the Eastern Health Cytology Laboratory between 1 January 2010 and 31 December 2013 were identified. Electronic medical records were examined for follow-up modalities and final histologic diagnosis. The final outcomes were reported as benign, malignant, or undetermined., Results: Out of 3,285 thyroid FNAs, 181 (5.5%) were AUS. Fifty-seven (31.5%) had repeat FNA diagnosed as benign (38.6%), AUS (29.8%), or suspicious/malignant (8.8%). Eighty-four (46.4%) had surgery after the first AUS diagnosis, 39 (46.4%) of which were malignant. Twenty-four patients (13.3%) were followed up by serial ultrasound only, 2 (1.1%) by molecular testing, and 1 (0.6%) died of unrelated disease. Thirteen (7.2%) had no follow-up record. Our malignancy rate (MR) was 29.8%., Conclusion: The MR in our population was higher than the rate proposed by The Bethesda System for Reporting Thyroid Cytopathology. Repeat FNA can reduce the rate of unnecessary surgeries, but practice guidelines should consider individual and institutional circumstances. The ratio MR:ADR (AUS diagnostic rate) may be a better indicator of performance., (© 2018 S. Karger AG, Basel.)

Background: In patients undergoing active surveillance of papillary thyroid microcarcinoma, definitive therapy-usually preceded by a definitive diagnostic procedure-is not recommended until evidence of disease progression is obtained, as stated in the American Thyroid Association guidelines. This is because the deferring of definitive diagnosis and therapy until disease progression has no impact on the disease-specific survival. This study evaluated the malignancy rate and probability of thyroid nodules, which was further stratified based on the size cutoff value of 1 cm, with suspicious findings on ultrasonography (US), by using various malignant stratification systems., Methods: The data were retrospectively collected between January 2003 and June 2003 from nine university hospitals that had previously participated in the Korean Society of Thyroid Radiology multicenter study on the ultrasonographic differentiation between benign and malignant thyroid nodules. In total, 829 thyroid nodules from 711 patients (620 women, 91 men; M age  = 48.7 years; range 6-98 years; 351 malignant and 478 benign nodules) were included. The probability for malignancy of thyroid nodules was calculated, which was further stratified by size, by using four different types of malignant risk-stratification systems. The factors that could differentiate benign from malignant nodules were assessed using the chi-square test., Results: In the suspicious thyroid nodules <1 cm on US, the malignancy probability ranged from 77.4% to 82.8%; the lowest rate was found in the Korean Society of Thyroid Radiology multicenter study, whereas the highest rate was noted in the Web-based system. Thus, the probability of benign nodules among suspicious thyroid nodules <1 cm on US was 17.2-22.6%., Conclusion: A biopsy should be considered before active surveillance to exclude benign nodules with suspicious US features, and could thus prevent unnecessary active surveillance and patient anxiety.

Background: The Bethesda system for reporting thyroid cytopathology (TBSRTC) was introduced to standardize the communication of fine-needle aspiration cytology (FNAC) interpretation between clinicians and pathologists. This study was undertaken to evaluate the diagnostic utility of TBSRTC for reporting thyroid FNACs and rate of malignancy in each diagnostic category of TBSRTC., Methods: A total of 603 thyroid FNAC results were retrieved retrospectively between July 2012 and January 2015 and reclassified according to TBSRTC. Of these, 392 cases had a histopathological follow-up. The FNACs results were compared to the histopathological diagnoses and the malignancy rates of each diagnostic categories of TBSRTC were calculated., Results: Of the 603 FNACs, nondiagnostic were 16 (2.7%), benign were 393 (65.2%), atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) were 60 (10%), follicular neoplasm/suspicious for a follicular neoplasm (FN/SFN) were 64 (10.6%), suspicious for malignancy (SM) were 32 (5.3%), and malignant were 38 (6.3%). In 392 cases, there was follow-up histopathology. The malignancy rate for nondiagnostic, benign, AUS/FLUS, FN/SFN, SM, and malignant categories were 0%, 0.8%, 24.4%, 28.9%, 70.8%, and 100%, respectively., Conclusion: Our study validated the efficacy of TBSRTC. In conclusion, the malignancy rate of AUS/FLUS in this study was higher than the risk mentioned in TBSRTC and other published studies. Hence, AUS/FLUS category patients in our setup warrant further workup including ultrasound and/or thyroid scan in addition to immediate repeat FNAC., (Copyright © 2016 Chang Gung University. Published by Elsevier B.V. All rights reserved.)