Application of the Bethesda System for Reporting Thyroid Cytopathology in the Eastern Province of Saudi Arabia: phase I pilot retrospective analysis

Patient Compliance With Surveillance of Thyroid Nodules Classified as Atypia of Undetermined Significance

OBJECTIVE

To determine whether thyroid nodule surveillance compliance is influenced by patient demographics or plan type.

STUDY DESIGN

Retrospective case series from 2010 to 2018.

SETTING

United States Military Health System.

METHODS

There were 481 patients with a thyroid nodule fine-needle aspiration classified as atypia of undetermined significance for whom treatment and follow-up information were available. Demographic information and surveillance plan type were extracted from the medical record and statistical analysis was performed to determine whether these characteristics influenced compliance rates.

RESULTS

A total of 289 nodules were surveilled and 192 diagnostic lobectomies were performed. An initial surveillance plan was documented in 93% (268/289) and 86% (231/268) complied. The most common plans were repeat biopsy in 78% (210/268) or ultrasound in 20% (53/268). A second plan was documented in 88% (204/231) of those who complied with the first. The most common second plans were ultrasound in 87% (178/204) or repeat biopsy in 8% (17/204). Compliance with the second plan was 64% (130/204), significantly lower than with the first (OR 3.6, 95% CI: [2.3, 5.6], P < .0001). Only 45% (130/289) were surveilled twice. Age and gender did not significantly affect compliance rates. Compliance with primary care ultrasound surveillance was 40% (21/52), significantly lower than with a specialist (77% [137/179]; OR 4.8, 95% CI: [2.5, 9.3, P < .0001).

CONCLUSION

Compliance with surveillance of thyroid nodules classified as atypia of undetermined significance was poor in this military cohort. Ultrasound surveillance by a specialist may be more reliable than with primary care.

False positive cases in thyroid cytopathology - the experience of a single laboratory and a systematic review

INTRODUCTION

Fine needle aspiration (FNA) is fundamental in the pre-operative assessment of thyroid nodules. However, the shining success of thyroid FNA is occasionally eclipsed by false positive (FP) cytological diagnoses. We describe our experience regarding FP cytological diagnoses and present a literature review concerning FP rates.

MATERIALS AND METHODS

We retrospectively analyzed 2031 consecutive cytology reports. FP was defined as a case with "suspicious for malignancy" or "malignant" cytology, whose surgical follow-up failed to confirm the initial diagnosis of malignancy. We used the PubMed database for the literature review using specific search terms ("thyroid", "cytology", "false positive").

RESULTS

Out of 2031 FNA reports, 93 cases with "suspicious for malignancy" or "malignant" cytology underwent surgical excision. Histopathology did not confirm malignancy in 10 cases (0.6% FP rate). Nodules with FP cytology were significantly larger (P = 0.0024) than those with with TP (true positive) cytology. A review of 25 publications shows comparable results to ours with some slight differences. The majority of studies achieve a FP rate below 3%. Most FP cytological diagnoses turn out to be non-neoplastic lesions (nodular hyperplasia, adenomatous nodule, lymphocytic thyroiditis), which combined account for 80.5% of all histological diagnoses.

CONCLUSIONS

Thyroid nodules with FP cytology were larger than nodules with TP cytology. Most studies manage to adhere to the recommended FP rates, or values close to them, with some outliers. Nevertheless, the mean FP rate values are very close to the value recommended by The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). The FP rate value depends on how one defines true negative cases, which can be either histologically proven benign cases, via a benign clinical course, or by assuming that cytologically benign cases remain as such.

Evaluation of Thyroid Fine-Needle Aspiration Biopsies according to Cytological Methods and Comparison with Histopathological Diagnosis

Objectives:

In this study, we aim to compare the results of aspiration of thyroid nodules evaluated according to the Bethesda category (BC) with tissue diagnoses in the operation materials and to compare the sensitivity, specificity and accuracy rates according to cytology methods.

Methods:

The previous fine-needle aspiration biopsy (FNAB) of thyroid nodules of 879 cases diagnosed histopathologically between 2010 and 2017 was examined. The FNAB results determined according to the Bethesda system were matched with tissue diagnoses, sensitivity, specificity, and accuracy rates were investigated according to cytology methods.

Results:

Sensitivity, specificity, Positive predictive value (PPV), Negative predictive value (NPV) and accuracy rates were found in all FNAB results (in units of %; Sensitivity; 84.7, Specificity; 81.1, PPV; 74.1, NPV; 89.2, Accuracy; 82.5). All of the cytological evaluation methods of thyroid FNABs were found to be reliable and effective (Generally, the results are 80% and above). Specificity and accuracy rates were close to the general average (82.5%) in all methods. However, in cases evaluated with liquid base cytology (LBC) method and in addition to LBC or conventional smear (CS), the sensitivity rates in cases where cell block (CB) were evaluated together were higher than cases in which LBC and CS were used alone (92.6% and 91.0%). When examined statistically, there was no significant difference concerning sensitivity, specificity and accuracy rates of cytological methods (p>0.05, respectively, p=0.576, 0.065, 0.643).

Conclusion:

In cytopathology, when evaluating thyroid aspirations, it is seen that the LBC method is used instead of CS. In our study, we recommend the use of the LBC method, which seems to have the highest sensitivity (taking into account its technical advantages), instead of CS. However, we think that both CS and LBC methods should be evaluated by supporting them with cell block sections.

Diagnostic Lobectomy for Bethesda III Thyroid Nodules: Pathological Outcomes and Risk Factors for Malignancy

OBJECTIVE

An indeterminate thyroid nodule fine-needle aspiration (FNA) presents a unique dilemma. We evaluated our institution's experience with Bethesda III thyroid nodules, including the risk of malignancy (ROM) of these nodules removed for diagnostic lobectomy and radiologic and clinical risk factors for malignancy.

STUDY DESIGN

Retrospective chart review.

SETTING

San Antonio Military Medical Center (SAMMC; 483 bed Military Treatment Facility and Level 1 Trauma Center).

METHODS

We identified all patients with a Bethesda III thyroid FNA at our institution from 2010 to 2018 and determined which nodules were removed. The final histological diagnosis was recorded. Whether or not age, gender, body mass index (BMI), race, nodule size, margin regularity, rate of nodule growth, vascularity, internal calcifications, family history of thyroid cancer, personal history of radiation, and history of repeated AUS/FLUS on FNA had a significant impact on malignancy risk was evaluated with chi square and rank sum Wilcoxon tests.

RESULTS

492 patients had 1 or more AUS result. 52% (258/492) underwent repeat FNA. This resulted in Bethesda II or III in 90% (232/258). In 10% (26/258), the repeat FNA resulted in a higher Bethesda grade. 183 lobectomies were performed on the side containing an AUS nodule. The malignancy percentage was 38.3% (70/183). Age less than 30 was the only variable showing statistical significance for increased risk of malignancy (P = .04).

CONCLUSION

The ROM of nodules characterized as AUS/FLUS on FNA may be higher than expected. Age may be a better predictor of malignancy than repeat FNA.

Indian experience of AUS/FLUS diagnosis: is it different from rest of Asia and the West?-A systematic review and meta-analysis

Background

Atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) is the most heterogeneous subcategory of the Bethesda system for thyroid cytopathology with laid down permissible limits of frequency and risk of malignancy (ROM). Due to differences in thyroid clinical practice worldwide, variations have been found in frequency, resection rates (RR) and ROM. Therefore, this systematic review and meta-analysis of AUS/FLUS across different regions was conducted and comparison of data from India was done with the rest of Asia and the West.

Methods

We searched PubMed and Google search engines from January 2009-Dec 2019 using terms "AUS Thyroid" and "FLUS Thyroid". Meta-analysis was performed using DerSimonian-Laird method and 95% confidence intervals were calculated using random effects model. Independent samples t-test was used to compare frequency, RR, and ROM of AUS/FLUS between India, rest of Asia and the West.

Results

Out of 15,000 studies on internet, 60 (18 Indian, 12 Asian and 30 Western) were included. Total aspirates were 201,657; 14,279 Indian, 62,448 Asian, 124,930 Western. Pooled estimates were: frequency 7.3% (6.3-8.3%), RR 41.9% (37.4-46.6%), ROM 33.3% (26.8-39.9%). Pooled prevalence of rate did not vary significantly across the three regions. Pooled prevalence of RR was highest in India (52.9%) and lowest in rest of Asia (26.5%); of ROM was highest in Asia (45.9%), lowest in the West (26.3%) (P<0.01). Statistical analysis demonstrated publication bias, limited to Indian and Western studies. Papillary thyroid carcinoma was the most common surgical diagnosis (87.9%; 1,082/1,231).

Conclusions

This meta-analysis showed differences in thyroid clinical practice followed in India, rest of Asia and the West. Although pooled prevalence of rate of AUS/FLUS was similar across the three, pooled RR and ROM varied. AUS/FLUS nodules were more frequently resected in Indian and Western studies than in rest of Asia. ROM was higher than recommended values in all three areas, being intermediate for India.

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

Background

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

Methods

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

Results

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

Conclusions

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

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.

Differences in surgical resection rate and risk of malignancy in thyroid cytopathology practice between Western and Asian countries: A systematic review and meta-analysis

There is increasing evidence showing that clinicians employ different management strategies in their use of The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). In this meta-analysis, we investigated the differences in diagnosis frequency, resection rate (RR), and risk of malignancy (ROM) between Western (ie, American and European) and Asian cytopathology practices. We searched PubMed and Web of Science from January 2010 to January 2019. Proportion and 95% CIs were calculated using a random-effect model. We used independent sample t tests to compare frequencies, RR, and ROM between Western and Asian practices. We analyzed a total of 38 studies with 145,066 fine-needle aspirations. Compared with Asian practice, Western series had a significantly lower ROM in most of TBSRTC categories, whereas the RR was not statistically different. Focusing on indeterminate nodules, the RR in Western series was significantly higher (51.3% vs 37.6%; P = .048), whereas the ROM was significantly lower (25.4% vs 41.9%; P = .002) compared with those in Asian series. The addition of Asian cohorts increased ROM for most of diagnostic categories compared with the original TBSRTC. In conclusion, this study demonstrates a difference in Western and Asian thyroid cytology practice, especially regarding the indeterminate categories. Lower RR and higher ROM suggest that Asian clinicians adopt a more conservative approach, whereas immediate diagnostic surgery is favored in Western practice for indeterminate nodules. The addition of Asian series into a meta-analysis of TBSRTC altered ROM for several categories, which should be considered in future revisions of TBSRTC.

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 and management of thyroid nodules with atypia/follicular lesion of undetermined significance on fine-needle aspiration

Since the introduction of the Bethesda System for Reporting Thyroid Cytopathology in 2008, the management of thyroid nodules has become more standardized, with clearly defined algorithms based on risk of malignancy for each of the six cytologic categories. However, the management of a thyroid nodule with a fine-needle aspiration biopsy classified as Bethesda III, or atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS), remains controversial due to the cytologic heterogeneity and the variability in the reported rates of malignancy. In this review, the history and rationale for the new Bethesda III category is examined, the reported incidence and risk of malignancy from published studies is reviewed and recommendations for management of patients with a thyroid nodule and AUS/FLUS are provided. Recent advances in molecular analysis and their role in the evaluation of patients with AUS/FLUS are also discussed.

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.

Review of the Bethesda System for Reporting Thyroid Cytopathology: a local study in Bohol Island, Philippines

OBJECTIVES

The aim of this study was to evaluate the adaptability and reproducibility of the Bethesda System for Reporting Thyroid Cytopathology (BSRTC) in a local setting and to determine the risk of malignancy for each category.

MATERIALS AND METHODS

A retrospective cross-sectional study of 80 thyroid fine-needle aspiration cytology cases using the BSRTC with corresponding histopathology was done between September 2009 and December 2012. Agreement scores were calculated using kappa statistics.

RESULTS

Consensus among two readers was attained for 73 cases (91.25%). No disagreement was noted for the malignant cases. The strength of agreement was very good, with a kappa statistic of 0.90. The risk of malignancy observed histologically was as follows: benign 3%, atypia of undetermined significance (AUS) 50%, suspicious for follicular/Hürthle cell neoplasm 50%, suspicious for malignancy 78%, and malignant 100%.

CONCLUSION

In this study, there is an outstanding reproducibility for the classification scheme. The application of the BSRTC as the standardized reporting is readily adaptable and therefore its application in larger medical centers is highly recommended. Our findings of a higher risk of malignancy seen in AUS (50%) and malignant (100%) categories in those who underwent surgical resection corroborated other published studies. Conveying this risk to clinical colleagues is important and will facilitate optimal patient care.

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.

Thyroid cytopathology with an emphasis on the 'atypical cells of uncertain significance' category: a 3-year audit with cytohistologic correlation

BACKGROUND

The National Cancer Institute meeting of 2007 resulted in the reporting terminology for thyroid cytopathology. The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) aims to standardise thyroid cytopathology reporting for cytology centres and clinicians alike.

STUDY OBJECTIVE

To compare our laboratory's performance against TBSRTC. The second aim was to determine our laboratory's atypia of undetermined significance/follicular cells of undetermined significance (AUS/FLUS) reporting rate and malignant outcomes. Our laboratory subclassifies the AUS/FLUS category into AUS/FLUS not otherwise specified (NOS) and AUS/FLUS cannot exclude malignancy.

MATERIALS

All thyroid reports were retrieved from our computerised database for the period of January 1, 2008 to March 31, 2011. Histologic correlation was obtained where available, and cases were classified according to their original diagnosis into 1 of the 6 categories of TBSRTC.

RESULTS

A total of 1,767 cases were retrieved. The categories were as follows: inadequate (n=415; 23%), benign (n=1,063; 60%), AUS/FLUS (n=141; 8%) [NOS (n=93; 5%) and cannot exclude malignancy (n=48; 3%)] suspicious for follicular/Hürthle cell neoplasm (n=68; 4%), suspicious for malignancy (n=37; 2%) and malignant (n=43; 2%). The malignant rates for the categories were as follows: -6 (26%), 0 (0%), 8 (40%), 9 (38%), 11 (42%), 15 (62.5%), and 15 (94%), respectively.

CONCLUSION

We have shown that the AUS category carries a higher malignant rate than that of the AUS category in TBSRTC of 5-15%. We conclude that subclassifying the AUS/FLUS category into NOS and cannot exclude malignancy helps to better identify patients with an increased risk of malignancy in the AUS/FLUS cannot exclude malignancy category.

Thyroid atypia of undetermined significance or follicular lesion of undetermined significance: an indispensable Bethesda 2010 diagnostic category or waste garbage?

OBJECTIVE

The Bethesda System for Reporting Thyroid Cytopathology (BSRTC) was introduced in thyroid cytology in 2007 and is now generally accepted. BSRTC categories include a morphologic description and risk of malignancy as well as follow-up suggestions in each group. However, the category entitled 'atypia of undetermined significance or follicular lesion of undetermined significance' (AUS/FLUS) is problematic. This category is heterogeneous and has been overused so far.

STUDY DESIGN

Twenty-six studies were included in a meta-analysis. In addition to AUS/FLUS percentage, we analysed repeated AUS/FLUS percentage, cytological and histological correlations, and risk of malignancy and neoplasm for AUS/FLUS. Furthermore, stratification, inter- and intra-observer variability, and the possibility of a switch to another category and its clinical consequences were reviewed.

RESULTS

Out of a total of 81,833 cases, AUS/FLUS accounted for 10.9%, with a 34% risk of malignancy. Persistent AUS/FLUS was found in 21.6% in repeated cytology. Cytohistological correlation was analysed from 16 studies (4,964 cases), revealing 10.4% as AUS/FLUS and a 21.5% risk of malignancy.

CONCLUSIONS

An AUS/FLUS category seems to be currently reasonable with clearly defined cytomorphological criteria which do not correspond unequivocally with those of the other categories. An AUS/FLUS category is justified and possible means of its improvement with immunohistochemistry, molecular analysis and imaging are discussed.