A single institution experience with the new bethesda system for reporting thyroid cytopathology: correlation with existing cytologic, clinical, and histological data

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Atypia of undetermined significance/follicular lesion of undetermined significance: Asian vs. non-Asian practice, and the Singapore experience

The Bethesda System for Reporting Thyroid Cytopathology has paved the way for comparisons of the practice of thyroid cytology in many different regions. However, there have been comparatively few studies documenting differences between Asian and non-Asian practice. Here, we aim to compare a few key parameters between the two regions, focusing on the indeterminate category of atypia of undetermined significance (AUS)/follicular lesion of undetermined significance (FLUS). We compared its incidence, resection rates (RRs), risk of malignancy (ROM), rate of repeat fine needle aspiration (rFNA), ROMs of cytomorphologic subcategories of nuclear atypia (AUS-N) vs. architectural atypia (AUS-A), and, finally, the incidence of papillary thyroid carcinoma (PTC) vs. follicular neoplasms (FNs) in resected AUS/FLUS cases in Asian and non-Asian regions. Where possible, these metrics were compared with the Singapore experience from a tertiary referral institution. While the incidence of AUS/FLUS was similar in both regions, we found geographical differences in the RRs and ROMs, which may reflect a higher collective threshold for surgery in Asian countries. However, both cohorts showed higher ROMs in the AUS-N subcategory as compared to the AUS-A subcategory, supporting the subclassification of the AUS/FLUS based on the presence of nuclear atypia. We also observed a higher incidence of AUS-N coupled with a higher incidence of PTC in resected AUS/FLUS nodules in Asian cohorts, while AUS-A and follicular-patterned neoplasms featured more prominently in the non-Asian cohorts. These incidences may account for the starkly different molecular approaches that we noted-in Asian (chiefly Korean and Chinese) centers, BRAF mutational analysis was favored, while gene panels and gene expression classifiers were more frequently applied in non-Asian centers (chiefly in the United States of America). Overall, the data from Singapore appears more closely aligned to non-Asian trends, despite its geographical location in Southeast Asia and its predominantly Asian population. We conclude that there is significant heterogeneity in the outcomes of the AUS/FLUS categories between and within regions, which is only partially explained by regional variations, and may also reflect different regional diagnostic and management practices. This highlights the importance of understanding the local context in the interpretation of indeterminate Bethesda categories, rather than adopting a "one-size fits all" approach.

Strategy to reduce unnecessary surgeries in thyroid nodules with cytology of Bethesda category III (AUS/FLUS): a retrospective analysis of 667 patients diagnosed by surgery

PURPOSE

Fine-needle aspiration (FNA) is widely used for the diagnosis of thyroid nodules detected by ultrasonography. However, the cytology of atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) often leads to unnecessary thyroid surgery. This study aimed to identify a strategy to reduce unnecessary surgeries in patients with AUS/FLUS nodules.

METHODS

Medical records of 667 patients with the cytology of AUS/FLUS who underwent surgery from January 2007 to December 2017 were retrospectively reviewed. Clinicopathological data were analyzed to identify malignant factors in thyroid nodules with AUS/FLUS. Factors were compared between patients with thyroid cancer and those with benign thyroid nodules, using stepwise multivariate logistic regression and decision tree model.

RESULTS

Pathological thyroid cancer was identified in 193 (43.3%) patients. There was a significant difference in malignancy incidence with respect to family history, number of nodules, number of FNAs, ultrasonographic finding, lymphocytic thyroiditis, and BRAFV600E mutation. Multivariate analysis showed that ultrasonography (K-TIRADS 5) was the most influential independent predictor of malignancy in AUS/FLUS (odds ratio = 11.02, p < 0.001), followed by possessing BRAFV600E mutation (odds ratio = 4.54, p < 0.001). This strategy enabled 226 (89.3%) patients to avoid unnecessary surgeries based on the decision tree model. There was no node of repeated FNA in the decision tree model, which reduced the risk of malignancy (odds ratio = 0.35, p = 0.029).

CONCLUSION

K-TIRADS 5 and BRAFV600E mutation were predictive of malignancy in nodules of AUS/FLUS. These factors should be considered in strategies to reduce unnecessary surgeries for AUS/FLUS.

The Implementation of the Bethesda System for Reporting Thyroid Cytopathology Improves Malignancy Detection Despite Lower Rate of Thyroidectomy in Indeterminate Nodules

BACKGROUND

The Bethesda system for reporting thyroid cytopathology (TBSRTC) was developed in 2009 to standardize the terminology for interpreting fine-needle aspiration (FNA) specimens.

METHODS

A historical prospective case series design was employed. The study group included patients with a thyroid nodule classified as TBSRTC AUS/FLUS (B3) or FN/SFN (B4) in 2011-2012 in a tertiary university-affiliated medical center. Rates of surgery and malignancy detection were compared to our pre-TBSRTC (1999-2000) study.

RESULTS

Of 3927 nodules aspirated, 575 (14.6%) were categorized as B3/B4. Complete data were available for 322. Thyroidectomy was performed in 123 (38.2%) cases: 66/250 (26.4%) B3 and 57/72 (79.2%) B4. Differentiated thyroid cancer was found in 66 (53.7%) patients: 30/66 (45.5%) B3 and 36/57 (63.2%) B4 (p=0.075). Operated patients were younger than the non-operated (B3: 52.4±16 vs. 59.7±13 years, p=0.009; B4: 51.7±15 vs. 60.5±14 years, p=0.042), and operated B3 nodules were larger than the non-operated (27.2 vs. 22.2 mm, p=0.014). Additional FNA was done in 160 patients (49.7%): 137/250 (54.8%) B3 and 23/72 (31.9%) B4 (p=0.002). The additional B3 nodules aspirations yielded a diagnosis of B2 in 84 patients (61.3%), B3 in 48 (35%), and B4 in 5 (3.6%). Of the 23 repeated B4 aspirations, B2 was reported in 5 (21.7%), B3 in 12 (52.2%), B4 in 4 (17.4%), and B6 in 2 (8.7%). The number of aspirated nodules was twice that reported in 1999-2000. The rate of indeterminate nodules increased from 6 to 14.6%, the surgery rate decreased from 52.3 to 38.2%, and the accuracy of malignancy diagnosis increased from 25.9 to 53.7%.

CONCLUSIONS

The application of TBSRTC significantly improves diagnostic accuracy for indeterminate thyroid nodules, leading to higher rates of malignancy detection despite lower rates of thyroidectomies.

Value of TIRADS, BSRTC and FNA-BRAF V600E mutation analysis in differentiating high-risk thyroid nodules

The thyroid imaging reporting and data system (TIRADS) and Bethesda system for reporting thyroid cytopathology (BSRTC) have been used for interpretation of ultrasound and fine-needle aspiration cytology (FNAC) results of thyroid nodules. BRAF(V600E) mutation analysis is a molecular tool in diagnosing thyroid carcinoma. Our objective was to compare the diagnostic value of these methods in differentiating high-risk thyroid nodules. Total 220 patients with high-risk thyroid nodules were recruited in this prospective study. They all underwent ultrasound, FNAC and BRAF(V600E) mutation analysis. The sensitivity and specificity of TIRADS were 73.1% and 88.4%. BSRTC had higher specificity (97.7%) and similar sensitivity (77.6%) compared with TIRADS. The sensitivity and specificity of BRAF(V600E) mutation (85.1%, 100%) were the highest. The combination of BSRTC and BRAF(V600E) mutation analysis significantly increased the efficiency, with 97.8% sensitivity, 97.7% specificity. In patients with BSRTC I-III, the mutation rate of BRAF(V600E) was 64.5% in nodules with TIRADS 4B compared with 8.4% in nodules with TIRADS 3 or 4A (P < 0.001). Our study indicated that combination of BSRTC and BRAF(V600E) mutation analysis bears a great value in differentiating high-risk thyroid nodules. The TIRADS is useful in selecting high-risk patients for FNAB and patients with BSRTC I-III for BRAF(V600E) mutation analysis.

Application of the Bethesda System for Reporting Thyroid Cytopathology in the Eastern Province of Saudi Arabia: A Follow-Up Study

This is a follow-up study to our previous analysis of thyroid aspirates utilizing the Bethesda System for Reporting Thyroid Cytology (BSRTC). The same study design was utilized for 2 years comparing 2 periods. A total of 251 thyroid aspirates from 218 patients were reviewed and deemed comparable to the previous cohort. The variance and consequently the number of interpretations dropped from 26 to 11 with a statistically significant 58% reduction and more consistency. Our unsatisfactory rate dropped from 22 to 10% (reduction of 55%). The risk of malignancy in this follow-up study showed a similar trend: an increase in risk with each step up in the BSRTC categories starting from the 'nondiagnostic' and up to 'malignant'. Few of our benign cases ended up with resection. We noticed sensitivity to the word 'follicular' in this benign category; therefore we propose a modification of the current BSRTC system by omitting the word 'follicular' from the benign category. We strongly believe that this modification harbors no serious damage to the intentions of BSRTC. This follow-up study has shown that the previous awareness campaign about the implementation has worked and can be considered a valid performance improvement program.

Ultrasound-guided core-needle biopsy in thyroid nodules. A study of 676 consecutive cases with surgical correlation

OBJECTIVES

To analyze the diagnostic accuracy of ultrasound-guided core-needle biopsy (CNB) of thyroid nodules.

METHODS

Of 3517 CNBs performed using an 18G spring-loaded device in one institution, we retrospectively reviewed 676 nodules in 629 consecutive patients who underwent surgery. CNB and pathological examination were compared. CNB diagnosis was standardized in four categories: insufficient (I), benign (B), follicular lesion (FOL), and malignant (M). Main outcome measures were predictive positive values (PPV), false positives (FP), and false negatives (FN).

RESULTS

CNB showed a low rate of insufficient and FOL diagnoses (5.8 % and 4.5 %). On surgery, there were eight FNs in 374 benign CNBs and three FPs in 148 malignant CNBs. The 154 nodules classified as FOL in CNB included, at surgery, 122 neoplasms; 28 of them malignant. PPV for malignancy of a malignant CNB was 98 %, and for a CNB diagnosis of FOL 18.2 %. Sensitivity for malignancy if CNB of FOL and M are considered positive was 95.6. Only one major complication was observed.

CONCLUSIONS

CNB is reliable, safe, and accurate to evaluate thyroid nodules and can be an alternative technique to FNA. It has low rate of non-diagnostic and undetermined cases, with high sensitivity and PPV.

KEY POINTS

Thyroid core-needle biopsy (CNB) has high sensitivity and PPV. Pitfalls of CNB are rare. Pitfalls are due to cystic cancer, histological heterogeneity, and mistakes in analysis. CNB is a reliable, safe, and accurate method to approach thyroid nodules. CNB can be used primarily or after insufficient or indeterminate FNA.

The Bethesda System for Reporting Thyroid Fine-Needle Aspiration Cytology: A Kuwaiti Experience - A Cytohistopathological Study of 374 Cases

INTRODUCTION

The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) identifies 6 diagnostic categories in which the risk of malignancy increases respectively. The aim of our study was to assess TBSRTC reporting in our hospital and to evaluate its specificity based on cytohistological correlation.

METHODS

A histological diagnosis was available in 374 (110 males and 264 females) out of 7,809 thyroid aspirates examined at Mubarak Al-Kabeer Hospital, Kuwait, from 2004 to 2012. The aspirates were classified in accordance with TBSRTC.

RESULTS

Thyroid aspirates were classified as nondiagnostic (n = 18; 4.8%), benign (n = 114; 30.5%); atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS; n = 59; 15.8%), follicular neoplasm/suspicious for follicular neoplasm (FN/SFN; n = 17; 4.5%), suspicious for malignancy (SM; n = 80; 21.4%), or malignant (n = 86; 23.0%). In 75 of 86 malignant cases, a papillary carcinoma was detected. There were 3 (1.6%) false-positive aspirates and the sensitivity, specificity, negative predictive value, and positive predictive value were 91.0, 61.9, 84.2, and 75.3%, respectively.

CONCLUSIONS

Our results are fairly comparable to those of various previous studies in the SM, AUS/FLUS, and SFN categories. The higher rates observed in the nondiagnostic and benign categories were possibly due to limited guided aspirations and a lack of on-site evaluation for all cases.

The impact of atypia/follicular lesion of undetermined significance and repeat fine-needle aspiration: 5 years before and after implementation of the Bethesda System

BACKGROUND

Limited studies have examined the impact of the Bethesda System for Reporting Thyroid Cytopathology (BSRTC) and specifically the category of atypia or follicular lesion of undetermined significance (AUS/FLUS). We studied their effects on reporting rates, subsequent management, and surgical outcome over a 10-year period, 5 years before and after implementation of the BSRTC.

METHODS

A retrospective review of thyroid fine-needle aspiration (FNA) reports from 2003 to 2012 was performed. Diagnoses made before BSRTC were reclassified into the most appropriate category. Repeat FNA results for all AUS/FLUS cases were recorded. Surgical follow-up results were matched by side and size of the targeted nodule. Incidental microcarcinomas were not considered "malignant" on excision. Malignancy rates were calculated based on excision and by all aspirated specimens.

RESULTS

Initial AUS/FLUS cases increased from 3% to 7% (P = .001) with implementation of the BSRTC. The nondiagnostic rate decreased from 19% to 10% (P = .026). Differences in malignancy rates before and after implementation of the BSRTC were not significant for all diagnostic categories. More repeat FNAs and fewer surgical excisions were performed after an initial AUS/FLUS diagnosis. Repeat FNA reclassified 56% of AUS/FLUS cases into a definitive category. The malignancy risks for AUS/FLUS plus benign and AUS/FLUS plus AUS/FLUS repeat FNAs were elevated compared with single benign and AUS/FLUS diagnoses.

CONCLUSIONS

AUS/FLUS cases are increasing with the implementation of the BSRTC. Given the potential increase in repeat FNAs as a result, it may be important to alert the clinician regarding the elevated malignancy risk of a benign or AUS/FLUS diagnosis associated with a prior AUS/FLUS finding.