Thyroid fine-needle aspiration cytology: malignancy rate in the category of indeterminate significant atypia/indeterminate significant follicular lesion

BACKGROUND

Fine needle aspiration cytology (FNAC) is a standard preoperative diagnostic modality for thyroid nodules. The Bethesda Thyroid Cytopathology Reporting System (TBSRTC) defines the FNAC atypia group as atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS).

OBJECTIVES

Determine the risk of malignancy after surgical resection in patients with AUS/FLUS.

DESIGN

Retrospective.

SETTING

Pathology department of a tertiary care center.

PATIENTS AND METHODS

All thyroid FNACs between 2015 and 2023 that were diagnosed as AUS/FLUS in Turkey. Patient demographics, preoperative ultrasonographic features, and follow-up data were collected.

MAIN OUTCOME MEASURES

Relationship between AUS/FLUS diagnosis and final histopathological diagnosis.

SAMPLE SIZE

562.

RESULTS

In total, 562 thyroid nodules were diagnosed as AUS/FLUS, and 267 (47.5%) were surgically excised. A malignant histopathological diagnosis was given in 28 cases (10.4%). Malignancy risk sensitivity of AUS/FLUS diagnosis was 75.68% (95% CI=58.80-88.23%), specificity was 55.24% (95% CI=50.91-59.52%), positive predictive value was 10.49% (95% CI=8.71-12.58%), and negative predictive value was 97.04% (95% CI=94.86-98.31%). In the ultrasonographic data, having symptomatic nodules, nodule calcification, and irregular nodule borders were all statistically significant signs of cancer in a one-variable analysis (P<.01). The presence of a family history emerged as a statistically significant prognostic marker for malignancy (P=.012). Although not statistically significant, the malignancy rate for nodules with nuclear atypia was 11.9%, significantly higher than the rate of 8.3% for nodules with architectural atypia only (P=0.32).

CONCLUSIONS

The diagnosis of AUS/FLUS has a high rate of predicting the risk of malignancy and should continue to be offered. In addition to cytopathological features, ultrasound data and family history should be taken into consideration when evaluating the case.

LIMITATIONS

Retrospective design and no molecular studies.

The value of monitoring amended reports in cytopathology quality programs: A biennial review

BACKGROUND

Quality and safety are the foundation of the practice of cytopathology. Review of key performance indicator (KPI) data can shine a light on laboratory vulnerabilities and potential areas for targeted improvement. The rate and content of amendment reports is a frequently monitored KPI in anatomic pathology, but few have studied its value in cytopathology. The goal of this study was to examine the frequency, classification, and outcome of amendments for a large cytopathology laboratory.

METHODS

All amendment reports issued for cases during a 2-year period from July 2019 to June 2021 were included in the study. Amendments were classified into three error type root causes: Specimen Identification Error, General Report Defects, and Diagnostic Error.

RESULTS

A total of 202 amendment reports were issued equating to a rate of 0.275%. A total of 83 (41.1%) were gynecologic cases and 119 (58.9%) were nongynecologic cases. Within the gynecologic cases, 13 (15.7%) cases were due to Specimen Identification Error, 13 (15.7%) cases were due to Diagnostic Error, and 57 (68.7%) cases were due to General Report Defects. Within the nongynecologic cases, 15 (12.6%) cases were due to Specimen Identification Error, 30 (25.2%) cases were due to General Report Defects, and 74 (62.2%) cases were due to Diagnostic Error with 32 of these due to true diagnostic change. Discovery methods included following re-review after additional clinical information was provided, reinterpretation after additional ancillary testing was performed, or conference review. There was no correlation with years in practice.

CONCLUSIONS

Studying amendment reports is an underrecognized and valuable quality assurance tool. Amendments can help provide information about types of errors, monitor laboratory processes, and help guide quality improvement endeavors.

Analysis of Clinical-Radiological-Pathological Factors in FN/SFN Bethesda Category Thyroid Nodules, Contribution of FNAB Repeat, Single Center Experience

Objectives:

Follicular neoplasm/suspected follicular neoplasm (FN/FNS) Bethesda Category (BC)-4 group cases are known as the gray zone. Nodules diagnosed in cytology are excised. However, very few of these nodules are malignant. Our aim is to investigate the usability of clinical-radiological-pathological parameters to reduce unnecessary surgery. In addition, we questioned the benefit of repeating fine-needle aspiration biopsy (rFNAB) in these nodules, which is not recommended, but performed for clinical or patient-related reasons.

Methods:

The files of all thyroid FNAB patients conducted in our institution between January 2014 and September 2020 were scanned in the database. In our study, 185 (5.1%) nodules with cytology results of which were classified as FN/FNS were identified among 3624 nodules that were applied FNAB during this period. Twenty-eight patients were excluded from the study group. 157 nodules belonging to 157 patients between the ages of 21 and 82 years who were operated and met the study criteria were identified from patients with these nodules. The files of all patients were scanned and the results of age, gender, ultrasonographic nodule characteristics, FNAB repeat, type of surgery, and postoperative pathology were recorded. All data were analyzed by comparing them with nodule features. SPSS 15.0 for Windows program was used for statistical analysis.

Results:

A significant correlation was found between the incidence of malignancy and male gender and hypervascularization (p=0.017 and p=0.002, respectively). Malignancy was less in nodules larger than 2 cm (p=0.014). There was no relationship between other clinical and radiological features and malignancy. In 29 nodules with rFNAB, a significant correlation was found between malignancy and advanced age (52.9-years-old), presence of nodules smaller than 2 cm and hypervascularization (p=0.047, p=0.047, and p=0.030, respectively).

Conclusion:

We recommend careful review of patients with hypervascular, hypoechogenic, and microcalcific BC-4 nodules (male gender and older patients at greater risk). Because of the serious risk of malignancy, patients with these features should be prepared for patient management with total thyroidectomy after examination with frozen section applied to the nodule during the operation.

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.

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.

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.

Malignancy Rate in Thyroid Nodules with Atypia or Follicular Lesion of Undetermined Significance

Introduction  Atypia of undetermined significance (AUS) or follicular lesion of undetermined significance (FLUS) is one of the six diagnostic categories of the Bethesda System for Reporting Thyroid Cytopathology. The prevalence of malignancy among Bethesda category III cytology is variable, ranging from 5% to 37% in the literature. Objective  To determine the rate of malignancy in thyroid nodules reported as Bethesda category III. Methods  A total of 495 patients underwent surgical intervention for thyroid nodules from January 2015 to December 2017. The present study included 81 cases reported as Bethesda category III, and their medical records were reviewed. Results  Out of 495 fine-needle aspiration cytology samples, 81 (16.4%) samples were labeled as AUS/FLUS. Among these 81 patients, the mean age was 43.0 years (± 13.9), with only 11 (14%) patients older than 55 years of age. Most of our patients were female ( n  = 69; 85.2%), and the rest were male. The rate of malignancy based on the final histology was of 33.3% ( n  = 27). The majority were 17 cases (21%) of papillary carcinoma, followed by follicular carcinoma ( n  = 6) (7.4%). Conclusion  The risk of malignancy can be higher than it is commonly believed, and guidelines should be based on the data from the institutions themselves for a better assessment of the outcomes.

Thyroid nodules with Hürthle cells: the malignancy risk in relation to the FNA outcome category

PURPOSE

The aim was to find whether the presence of Hürthle cells (HC) in a smear influences the categorization of FNA results or the risk of malignancy (RoM) of particular categories of cytological diagnosis.

METHODS

25,220 FNA performed in a single center in years 2005-2017 were analyzed. Almost all the examined patients were exposed to moderate iodine deficiency for most of their lives. The distribution of FNA outcome categories was compared between two groups: with or without HC (HC and non-HC). The RoM was evaluated on the basis of postoperative histopathological examination (3082 patients).

RESULTS

HC were found in 7.5% of diagnostic FNA. HC nodules were classified into categories II (78.2% vs. 91.9%, p < 0.0000) and VI (0.4% vs. 1.2%, p = 0.0017) less often than non-HC nodules, but more frequently to categories III (14.4% vs. 5.8%, p < 0.0000), IV (11.2% vs. 0.9%, p < 0.0000) and V (1.5% vs. 0.8%, p = 0.0013). There were no significant differences in RoM between HC and non-HC nodules. The RoM in HC and non-HC nodules of particular categories of the Bethesda system was as follows: II: 1.8% vs. 0.8%, III: 9.7% vs. 3.8% when only the last FNA was considered and 10.8% vs. 6.4% when the category III in any performed FNA was considered; IV: 12.7% vs. 10.9%; V: 41.7% vs. 58.2%; and VI: 100% vs. 96.9%.

CONCLUSIONS

HC nodules are classified into categories of equivocal cytological outcomes more often than nodules without HC. Nevertheless, the presence of HC in a smear does not significantly affect the RoM of FNA categories.

Ultrasound image analysis using deep learning algorithm for the diagnosis of thyroid nodules

Fine needle aspiration (FNA) is the procedure of choice for evaluating thyroid nodules. It is indicated for nodules >2 cm, even in cases of very low suspicion of malignancy. FNA has associated risks and expenses. In this study, we developed an image analysis model using a deep learning algorithm and evaluated if the algorithm could predict thyroid nodules with benign FNA results.Ultrasonographic images of thyroid nodules with cytologic or histologic results were retrospectively collected. For algorithm training, 1358 (670 benign, 688 malignant) thyroid nodule images were input into the Inception-V3 network model. The model was pretrained to classify nodules as benign or malignant using the ImageNet database. The diagnostic performance of the algorithm was tested with the prospectively collected internal (n = 55) and external test sets (n = 100).For the internal test set, 20 of the 21 FNA malignant nodules were correctly classified as malignant by the algorithm (sensitivity, 95.2%); and of the 22 nodules algorithm classified as benign, 21 were FNA benign (negative predictive value [NPV], 95.5%). For the external test set, 47 of the 50 FNA malignant nodules were correctly classified by the algorithm (sensitivity, 94.0%); and of the 31 nodules the algorithm classified as benign, 28 were FNA benign (NPV, 90.3%).The sensitivity and NPV of the deep learning algorithm shown in this study are promising. Artificial intelligence may assist clinicians to recognize nodules that are likely to be benign and avoid unnecessary FNA.

Cytomorphologic, Imaging, Molecular Findings, and Outcome in Thyroid Follicular Lesion of Undetermined Significance/Atypical Cell of Undetermined Significance (AUS/FLUS): A Mini-Review

OBJECTIVES

Since the introduction of the entity of "Atypical cell of undetermined significance /follicular lesion of undetermined significance" (AUS/FLUS) by The Bethesda System for Reporting Thyroid Cytology (TBSRTC) in 2007, there have been many published studies about the cytomorphologic criteria, subclassification, outcome, and management of patients with the diagnosis of AUS/FLUS. There have been many studies in different aspects of this indeterminate category, i.e., cytologic and molecular findings, ultrasonographic findings, and in some instances even core-needle biopsy to address a better and safer way of the management of patients with this fine-needle aspiration cytology diagnosis. The second edition of TBSRTC and the 2015 American Thyroid Association guidelines provide an update on the follow-up and management of AUS/FLUS. A multidisciplinary team consisting of pathologists, endocrinologists, surgeons, and radiologists should be involved in the diagnosis and management of AUS/FLUS, and all of them should be aware of the heterogeneity of this lesion for the prediction of the treatment and outcome.

STUDY DESIGN

In this review, we consider different research platforms (2008-2017) to find the best and key reports for the above-mentioned challenging aspects of AUS/FLUS.

CONCLUSION

AUS/FLUS is now a well-defined group of thyroid lesions, which can be most accurately diagnosed and managed with cytomorphology, molecular, and ancillary studies.

Malignancy rate of atypia of undetermined significance/follicular lesion of undetermined significance in thyroid nodules undergoing FNA in a suburban endocrinology practice: A retrospective cohort analysis

BACKGROUND

The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) was created to establish a standard terminology regarding thyroid nodules that can be shared between endocrinologists, pathologists, radiologists, and surgeons. Since its inception and use in 2009, multiple large hospitals and academic institutions have performed retrospective studies to compare their classification rates, specifically those of atypia of undetermined significance (AUS) and follicular lesion of undetermined significance (FLUS), with the recommended rates created by the National Cancer Institute. The current study compared AUS/FLUS rates at a private suburban endocrine practice with those of previous publications from large institutions and the rates established by the National Cancer Institute.

METHODS

Charts from 893 patients with fine-needle aspiration (FNA) performed in 2015 were reviewed. Data specific to thyroid aspirates classified as AUS/FLUS were organized into whether patients underwent surgery, underwent subsequent repeat FNA, or required continued observation. These results then were calculated to reveal the rate of malignancy in the AUS/FLUS category with surgical pathology in the study institution.

RESULTS

A total of 893 patients underwent FNA, with 43 patients (4.82%) shown to have AUS/FLUS. A total of 21 patients proceeded to undergo thyroidectomy or lobectomy, with 7 patients (33.3%) found to have papillary or follicular thyroid carcinoma.

CONCLUSIONS

The rate of use of the AUS/FLUS category for thyroid nodules examined at the study institution was found to be within the recommended range set forth by TBSRTC. However, the malignancy rates on histopathology in the study institution were found to be higher than the new proposed malignancy rates from TBSRTC published in 2017. This finding is comparable to those of multiple other community and academic institutions performed prior to and after institution of the new guidelines.

Risk factors associated with malignancy and with triage to surgery in thyroid nodules classified as Bethesda category IV (FN/SFN)

BACKGROUND

Thyroid nodules diagnosed as Bethesda category IV [follicular neoplasm/suspicious for follicular neoplasm (FN/SFN)] are recommended for surgery. However, only 10%-40% of these nodules turn out to be malignant on histopathological examination. Therefore, selection for surgery of nodules diagnosed as Bethesda category IV is important. We aimed to define predictive factors for malignancy and factors associated with triage to surgery.

METHODS

The records of all patients with nodules who underwent fine needle aspiration biopsy (FNAB) and classified by Bethesda reporting system as FN/SFN between January 2011 and July 2017 at our institution were reviewed. Univariate and multivariate analysis were performed to select independent factors associated with thyroid cancer, and with triage to surgery. Using independent risk factors for malignancy predictive index categories were created.

RESULTS

Among 6910 nodules that underwent FNAB, 180 (2.6%) were diagnosed as FN/SFN. Of the 180 patients, 139 (77%) underwent surgery with the associated malignancy rate of 37% (51/139) (upper boundary). Risk of malignancy among all FN/SFN nodules was 28% (lower boundary). Solid structure, size ≥ 4 cm, microcalcification, hypoechogenicity, and increased vascularization were found to be significant and independent risk factors associated for malignancy. None of the clinical and ultrasound factors were associated with triage to surgery.

CONCLUSIONS

Our findings showed that using predictive factors for malignancy in the Bethesda IV category as risk indices, 17% of patients who had nodules without any risk factors could be spared surgery. Predictive indices could be considered for the malignancy risk and for selection of patients for surgery.

Atypia of Undetermined Significance in Thyroid Fine-Needle Aspirations: Follow-Up and Outcome Experience in Newfoundland, Canada

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.

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.

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.

Institution-specific risk of papillary thyroid carcinoma in atypia/follicular lesion of undetermined significance

BACKGROUND

The Bethesda System for Reporting Thyroid Cytopathology (BSRTC) is used in surgical decision-making according to malignancy risk in each category. Malignancy risk in atypia/follicular lesion of undetermined significance (AUS/FLUS) is estimated in BSRTC to be 5% to 15%, but institutional data have varied widely.

METHODS

We conducted a post-BSRTC 4-year retrospective analysis of index thyroid nodule cytology and histopathology in an academic head and neck endocrine surgery setting.

RESULTS

Of 2939 thyroid cytology reports from 1944 patients, the most advanced BSRTC category was AUS/FLUS in 233 patients (12.0%) of which 187 went to thyroidectomy. In AUS/FLUS, the upper and lower boundary estimates of the malignancy rate were 46% and 37%, accordingly. The malignancy rate did not vary significantly by cytopathologist or cytopathologic features.

CONCLUSION

Malignancy rates in AUS/FLUS vary by institution from 6% to 46%. Given the subjective nature of thyroid cytopathology and interpretation of the BSRTC categories, guidelines should encourage the use of institution-specific data on malignancy risk in treatment decisions. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1210-E1215, 2016.

Risk of malignancy for each Bethesda class in pediatric thyroid nodules

PURPOSE

The Bethesda classification for cytology is used to classify thyroid nodules into one of six categories, and for each category there is an implied cancer risk and also recommendation for management. Despite lack of data in children, the American thyroid association promotes the use of the same management guidelines as in adults. Our aim was to study the risk of malignancy for each Bethesda class in children with thyroid nodules.

METHODOLOGY

We included all patients ≤18years of age that had underwent a thyroid fine needle aspiration (FNA) at one of two centers between January 1998 and July 2013. FNA results were reclassified according to the Bethesda criteria. Histological, repeat cytological, radiological and clinical follow-up were recorded.

RESULTS

Fifty-six patients (66 nodules) underwent FNB. Mean age was 13.6 years. Numbers of nodules reported as BI-BVI were 7, 38, 11, 4, 3 and 3, respectively. Follow-up was achieved for 55 (83%) nodules. Twelve (18%) nodules were malignant by histology and revealed papillary (n=7), follicular (n=3) or insular thyroid cancer (n=2), The proportion of nodules with malignancy for BI-BVI was: 0%, 0%, 18%, 100%, 100% and 100%.

CONCLUSION

The rate of malignancy in thyroid nodules in children seems to be higher than reported in adults. The Bethesda criteria seem to accurately identify benign nodules, but other categories have a very high rate of malignancy and BIII nodules pose a particular challenge.

FNA needle rinses preserved in Cytolyt are acceptable specimen type for mutation testing of thyroid nodules

INTRODUCTION

This study investigated the application of molecular testing to residual thyroid fine-needle aspiration material from needle rinses collected in Cytolyt.

MATERIALS AND METHODS

Two thyroid needle rinses from 135 patients were collected in Cytolyt during routine diagnostic workup in our institution. Molecular testing was performed to detect 14 genetic alterations in BRAF, K-, H-, N-RAS genes as well as RET/PTC1, RET/PTC3, and PAX8/PPARγ and verified by next generation sequencing and correlated with cytologic diagnoses.

RESULTS

Molecular testing revealed a total of 17 mutations across specimens with benign nodule (n = 5; HRAS, NRAS), Hürthle cell neoplasm (n = 2; BRAF, HRAS) and Papillary thyroid carcinoma (n = 10, 9 BRAF, 1 KRAS) cytology. No RNA gene rearrangements were detected.

CONCLUSIONS

Mutations and translocations associated with thyroid cancer can be detected in thyroid fine-needle aspiration needle rinses preserved in Cytolyt specimens collected during routine patient management, which are typically discarded when a diagnosis is attained.

The Bethesda System for Reporting Thyroid Cytopathology is applicable to frozen section diagnosis in children

The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) offers standardized and widely understood diagnostic categories for reporting thyroid cytology diagnoses. We compared the utility of TBSRTC categories in pediatric cytology diagnoses and pediatric intraoperative frozen section diagnoses. We examined the experience of our primary and referral care center over a 20-year period. This included 182 thyroidectomy patients who underwent 64 preoperative fine-needle aspirations and 91 intraoperative frozen section evaluations, including 38 patients evaluated sequentially by each method. All diagnoses were retrospectively reclassified into TBSRTC categories and correlated with the final thyroidectomy diagnoses. For each sampling method, malignant final diagnoses were observed at similar frequencies to rates predicted by TBSRTC. Malignant final diagnoses following fine-needle aspiration or frozen section diagnoses in TBSRTC categories other than malignant or suspicious for malignancy most often resulted from difficulty in detecting papillary carcinoma, including difficulty detecting the nuclear characteristics of papillary carcinoma in frozen sections. The limitations of needle biopsy and frozen section evaluations differ, yet serial utilization of these procedures was rarely informative. Based on the experience of our institution, classification of cytology and frozen section diagnosis by TBSRTC predicts a risk of malignancy similar to the guidance offered by TBSRTC. We recommend including a TBSRTC category when reporting either thyroid cytology or frozen section diagnoses in children.

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.

The Bethesda system for reporting thyroid cytopathology: a single-center experience over 5 years

BACKGROUND

The Bethesda System for Reporting Thyroid Cytopathology (BSRTC) was developed to refine fine-needle aspiration (FNA) cytology definitions and improve clinical management. This study evaluates the impact of the BSRTC 5 years after its adoption at a single institution.

METHODS

A total of 1,625 patients undergoing thyroidectomy in the pre-BSRTC (Group 1: July 2007-January 2009) and post-BSRTC (Group 2: February 2009-September 2013) periods were reviewed. Cytologic diagnoses in Group 1 included non-diagnostic, benign, follicular neoplasm, suspicious for malignancy and malignant. Atypia/follicular lesion of undetermined significance (AUS/FLUS) was included in Group 2. The proportions of each FNA category and malignancy rate per cytologic diagnosis were compared.

RESULTS

Fifty-four percent (187/347) of Group 1 patients had a preoperative FNA versus 61 % (777/1278) in Group 2 (p = 0.02). Group 1 FNA results included 3 % non-diagnostic, 48 % benign, 17 % follicular, 13 % suspicious for cancer, and 19 % cancer. Group 2 results included 3 % non-diagnostic, 36 % benign, 9 % follicular, 8 % suspicious for malignancy, 18 % malignant and 26 % AUS/FLUS. In Group 2, the proportions of benign, follicular and suspicious for malignancy FNAs decreased significantly (p < 0.05). In Group 2, there were more indeterminate FNA diagnoses overall (30 vs. 43 %; p < 0.001). The rate of cancer in suspicious for cancer FNA lesions increased from 44 to 65 % (p = 0.07). The AUS/FLUS malignancy rate was 15 %.

CONCLUSIONS

Since the adoption of the BSRTC at our institution, the proportion of indeterminate FNAs has increased; however, the diagnostic accuracy of the suspicious for cancer category improved. We recommend periodic review of the utilization and malignancy rates per cytologic category at each institution to help tailor clinical management.