The Bethesda System For Reporting Thyroid Cytopathology Research Articles

ODP481 Frequency and outcomes of reporting Bethesda class III thyroid cytopathology- An integrated health network's experience

Abstract Introduction Indeterminate thyroid nodule cytologic diagnosis causes anxiety and confusion to the patient and typically results in additional intervention including thyroid surgery. This increases risk of harm and cost of healthcare. The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) recommends that cytologists attempt to limit reporting 'indeterminate' [Bethesda III (B-III)] category when interpreting thyroid fine needle aspiration (FNA) specimens, and that all effort be made to limit this diagnosis to less or equal to 7% of all thyroid FNA cases. B-III encompasses follicular lesion of undetermined significance (FLUS) and atypia of undetermined significance (AUS). Because we noted a high reporting of B-III cases at our institution, we aim to review the cytologic interpretation of thyroid FNAs, specifically, the rate of indeterminate cytologic diagnoses. Our second aim is to assess the outcomes of nodules labeled as B-III category. Methods We reviewed the electronic medical records of adults who underwent FNA of thyroid nodules at Allegheny Health Network between January 1, 2016 and December 31, 2019. Results 700 patient records were reviewed, out of which 167 records were excluded (non-thyroid FNA or no relevant records). Meaningful records were available for 725 thyroid nodules biopsied during the study period (533 patient records). Mean age in our sample was 54.7±13.9 years and female-to-male ratio was 4: 1. Percent reporting of diagnostic categories based on Bethesda system were as follows: non-diagnostic/unsatisfactory (B-I) 8%; benign (B-II) 52%; FLUS/AUS (B-III) 28%; FN/SFN (B-IV) 6.2%; suspicious for malignancy (B-V)2.3%; and malignant (B-VI) 3.2%. Out of 28% reported as B-III, 73% were FLUS and 27% were AUS. Results of molecular diagnostic testing (ThyGeNEXT-ThyraMIR; Interpace Diagnostics®) were available for 95/203 of B-III category cases, of which 76% were labeled as very likely benign (probability of malignancy ≤5%) and 15% had low to moderate (10-40%) probability of malignancy. Only 9/95 (9%) had a ≥ 45% probability of malignancy. Four cases out of the 9 above cases were confirmed malignant and 1 was 'indeterminate' on surgical pathology. One in four of all B-III category nodules (n=52) underwent partial or total thyroidectomy, of which 32 were reported as benign, 18 malignant, one NIFTP, and one indeterminate by final surgical pathology. Conclusion We observed higher than recommended (28%) rate of B-III thyroid cytology at our institution. Most of these nodules underwent further interventions (molecular testing and/or thyroidectomy) where the majority were determined to be benign. All efforts should be made to decrease this rate with the ultimate goal of improving patient care, decrease unnecessary intervention, and reduce healthcare cost. Presentation: No date and time listed

Follicular Growth Pattern Disease on Thyroid Fine-needle Aspiration Biopsy

Thyroid nodules are a common worldwide health problem and a diagnostic challenge for clinicians and cytopathologists. Follicular growth pattern constitutes the majority of thyroid lesions. Thyroid nodules can be neoplastic or non-neoplastic, and neoplastic nodules can be classified as benign, malignant, or gray zone. Gray zone lesions include different benign and malignant entities that might be resulted in unnecessary thyroidectomies with risk of morbidity and higher health care costs. Depending on the cellularity, most cases might fall into the follicular neoplasia (FN)/ suspicious for FN (SFN) category or follicular lesion of undetermined significance (FLUS) in The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). Pathologists must be aware of the relationship between this diagnostic category and follow-up patient management and avoid over-diagnosing by mastering the diagnostic criteria.

Malignancy Rates by Bethesda Subcategory in the Pediatric Population.

While the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) is the most widely used method for categorizing thyroid nodules, its applicability to children is often debated. We describe our institution's experience utilizing the TBSRTC and examine the rates of malignancy in our population. We conducted a retrospective chart review of eligible patients undergoing primary thyroidectomy at a high-volume tertiary care pediatric hospital. All patients had pre-operative fine needle aspiration. Of the 112 patients in our cohort, 85 (76%) were female. The median age was 15.1 years. The patients were divided into groups based on the Bethesda categorization of the fine needle aspirations of their nodules. The percentages of patients whose resection specimens showed evidence of malignancy on the surgical pathology reports were recorded as follows: category I (n = 5): 20%, category II (n = 11): 0%, category III (n = 30): 17%, category IV (n = 13): 31%, category V (n = 17): 94% and category VI (n = 36): 100%. Our findings indicate that the malignancy rates at our institution are comparable to those reported by other high-volume studies. When compared with the 2017 TBSRTC data, we found that our results were similar in many categories, with the exception of categories I and V.

Molecular Characterization of Thyroid Follicular Lesions in the Era of "Next-Generation" Techniques.

It is unequivocally recognized that thyroid nodules are frequently detected in the adult population and mostly characterized by benign lesions (up to 70% of them), with only 5%–15% malignant lesions. The evaluation of thyroid lesions with fine-needle aspiration cytology (FNAC) represents one of the first and most useful diagnostic tools in the definition of their nature. Despite the fact that the majority of thyroid lesions are correctly diagnosed as either benign (70%–75%) or malignant (5%–10%) entities, the remaining nodules (20%–25%) represent the “gray zone” of follicular lesions, which belong to indeterminate categories, according to the different classification systems. This indeterminate group of lesions includes both benign and malignant entities, which cannot be easily discriminate with morphology alone. In these last decades, the increasing role of molecular testings, feasibly performed on cytological material combined with the discoveries of specific genetic alterations in the field of thyroid pathology, has opened the pace to their more accurate and specific contribution on cytology. In fact, in 2015, in the revised management guidelines for patients with thyroid nodules and well-differentiated thyroid cancers (WDTCs), the American Thyroid Association (ATA) confirmed the performance of molecular testing in thyroid indeterminate cytology, and the same performance was addressed in recent update of the management of thyroid nodules in the second edition of the Bethesda system for reporting thyroid cytopathology (TBSRTC). In the current review, we discuss the role of molecular tests for the different thyroid diagnostic categories of the Bethesda system for reporting thyroid cytopathology, mostly focusing our attention on the follicular and indeterminate lesions.

THE BETHESDA SYSTEM FOR REPORTING THYROID CYTOPATHOLOGY WITH HISTOPATHOLOGIC CORRELATION: A RETROSPECTIVE STUDY AT A TERTIARY CARE HOSPITAL OF LOWER ASSAM

Background: Fine needle aspiration is currently the preferred screening test for guiding the diagnosis and treatment of thyroid nodules as it is quick, assessible, inexpensive, relatively painless with quite accurate diagnosis. The Bethesda system for reporting thyroid cytopathology (TBSRTC) was introduced in 2007 in an attempt to standardize international terminology and to categorize morphological criteria in ne-needle aspirations (FNAs) from patients with thyroid nodules. It introduced 6 diagnostic categories for FNA results and assigns a malignancy risk and recommendations for patient management for each category. To categorize theObjectives: thyroid swelling following The Bethesda system for reporting Thyroid Cytopathology (TBSRTC) and to correlate with nal histopathological reports wherever available. : 99 patients underwent FNAC in our institute from the period of January 2019 to July 2020,Materials and Methods and were categorized according to the Bethesda system for reporting thyroid cytopathology. Results: The 99 cases taken up for FNAC were categorized according to The Bethesda system for reporting Thyroid Cytopathology (TBSRTC) as Non-diagnostic or unsatisfactory at 6.06%, Benign at 81.81%, Atypia of undetermined signicance at 0%, Suspicious for a follicular neoplasm at 4.04%, Suspicious for malignancy at 2.02%, Malignant at 6.06%. The sensitivity, specicity, positive predictive value (PPN), negative predictive value (NPN), and accuracy of FNAC in diagnosing thyroid malignancy were calculated as 66.67%, 100%, 100%, 93.33% and 94.12% respectively. The BethesdaConclusion: system for reporting Thyroid Cytopathology (TBSRTC) helps in standardization of thyroid ne needle aaspiration reporting. This leads to timely and adequate intervention for the patient and also minimizes unnecessary thyroid surgeries

Reproducibility of Cytomorphological Diagnosis and Assessment of Risk of Malignancy of Thyroid Nodules Based on the Bethesda System for Reporting Thyroid Cytopathology: A Tertiary Cancer Center Perspective.

The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) was introduced for unifying the terminology and morphologic criteria along with the corresponding risk of malignancy, leading to more consistent management approaches. The aim of this study was to study the utility and reproducibility of TBSRTC in reporting thyroid cytology in a referral cancer center. The fine-needle aspiration (FNA) of all thyroid nodules were included for a period of 5 years, from January 2016 to December 2021, in this cancer center. They were retrospectively reviewed and recategorized according to TBSRTC by two experienced pathologists. Cytohistopathological correlation was done for the cases which underwent surgical resection. 522 fine-needle aspiration cytology (FNAC) of thyroid swellings were evaluated and categorized according to TBSRTC. There was agreement in the cytological diagnosis of 512 cases, of which 260 (50.78%) were benign lesions, 189 (36.91%) were malignant, 5 (0.97%) were unsatisfactory/nondiagnostic, 41 (8.01%) were follicular neoplasm/suspicious for neoplasm, 13 (2.53%) were suspicious for malignancy, and 4 (0.78%) cases were reported as atypia of undetermined significance. Two cytopathologists were in agreement in 512 cases (98%) of cases. Almost complete concordance was noted in the malignant (99%) and benign categories (98%). Disagreement was seen in 10 cases. Histological follow-up was available in 201 cases with an overall malignancy rate of 62.68% (126/201). TBSRTC proved to be a very simple and effective reporting system for thyroid FNAC, especially in the setting of a cancer center. This enables proper triaging of cases with thyroid masses into those who require surgical intervention and those who can avoid it, thereby preventing unnecessary morbidity.

Comparison of Diagnostic Rates and Concordance with Subsequent Surgical Resections between Conventional Smear and ThinPrep Preparations versus ThinPrep Only in Thyroid Fine Needle Aspiration (T-FNA) Specimens

Background: Thyroid fine needle aspiration (T-FNA) is a mainstay in management of thyroid nodules. However, the preparation of T-FNA specimens varies across institutions. Prior studies have compared diagnostic rates between different specimen preparations of T-FNA specimens and their associated advantages and disadvantages. However, few have compared the rates of all diagnostic categories of The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) between liquid-based preparations (LBPs) and a combination of LBP and conventional smear (CS) preparations. Our study compares TBSRTC diagnostic rates between these 2 cohorts and correlates cytologic diagnoses with subsequent thyroid resections to evaluate rates of neoplasia (RON) and malignancy (ROM). Methods: 584 consecutive thyroid FNA specimens were collected and stratified by preparation type (ThinPrep [TP] vs. CS & TP). Diagnostic rates for each TBSRTC diagnostic category were calculated. The institution’s electronic medical records database was searched for histologic diagnoses of previously sampled thyroid nodules to evaluate the RON and ROM. Results: Of 584 thyroid FNA specimens, 73 (12.5%) and 511 (87.5%) were evaluated by TP only and CS & TP, respectively, reflecting the predominance of rapid on-site evaluation (ROSE) with CS for T-FNAs at our institution. Of the TP only and CS & TP cohorts, 29 (39.7%) and 98 (19.2%) had subsequent resections, respectively. The frequency of non-diagnostic cases was lower in the CS & TP cohort (12.7% vs. 26%). While the diagnostic rate of follicular lesion of undetermined significance was similar for both cohorts, SFN categorization was only utilized in the CS & TP cohort (1.5% vs. 0%). Although RON and ROM were similar between cohorts in many of the TBSRTC categories, there was a higher RON associated with non-diagnostic specimens in the TP only cohort when the denominator included all non-diagnostic cases. Conclusion: The combination of CS and LBP may potentially decrease the non-diagnostic rate of T-FNA specimens as well as the number of passes required for diagnosis, particularly with ROSE. Evaluation of morphologic features highlighted in conventional smears may facilitate diagnostic categorization in the “suspicious for follicular neoplasm” category.

BRAF V600E mutation and the Bethesda System for Reporting Thyroid Cytopathology of fine-needle aspiration biopsy for distinguishing benign from malignant thyroid nodules.

Background:The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) predicts the risk of malignancy for the different categories of the ultrasound-guided fine-needle aspiration biopsy (FNAB). The objective of this study is to investigate the efficiencies of the v-raf murine sarcoma viral oncogene homolog B1 (BRAF) V600E mutation test and the TBSRTC categories in distinguishing between benign and malignant thyroid nodules.Methods:In this study, 362 ultrasound-guided fine-needle aspiration (FNA) samples from 344 patients aged from 17 to 76 years old were retrospectively reviewed. The patients were classified into six groups (I–VI) according to the TBSRTC system. The amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) was used to evaluate the BRAF V600E mutation level in total 362 samples. Among of the 344 patients, 128 patients (131 thyroid nodules) who underwent surgeries were followed by histopathological examination. The predictive values of the BRAF V600E mutation test and TBSRTC categories were evaluated in these 131 thyroid nodules.Results:The median ages of the patients in the TBSRTC IV–VI group were smaller than those in the TBSRTC I–III groups. The proportion of nodules over 1 cm was larger than it in the TBSRTC IV group compared to the other groups. Significant differences in BRAF V600E mutation were observed (P < .001) among these six groups. The sensitivity (89.57%) for the detection of malignant thyroid nodules, negative predictive value (NPV; 45.45%) for the detection of benign nodules, and accuracy (86.26%) for distinguishing between benign and malignant thyroid nodules increased by combining the BRAF V600E mutation test and TBSRTC system when compared with the BRAF V600E mutation test and TBSRTC system respectively. The BRAF V600E mutation test alone demonstrated the increased positive predictive value (PPV; 98.91%) and specificity (93.75%) for the detection of malignant thyroid nodules compared to the TBSRTC method (alone or in combination with the BRAF V600E method).Conclusion:In summary, significant differences in age, nodule diameter, and BRAF V600E mutation were noted among the six categories of the TBSRTC system. The combination of the BRAF V600E mutation test and TBSRTC system demonstrated increases in the NPV, sensitivity, and accuracy, while the BRAF V600E method proved superiority to the TBSRTC system with regard to the PPV and specificity.

The evolution of "atypia" in thyroid fine-needle aspiration specimens.

The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) provided a standardized framework for resulting thyroid fine-needle aspiration (FNA) specimens and introduced the low-risk category of atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS). This indeterminate category has significantly evolved over time with the incorporation of molecular testing, reclassification of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), and a shift toward more conservative management. Despite these refinements, AUS/FLUS remains a challenge, at both the diagnostic and therapeutic level. We review the criteria for AUS/FLUS and the associated controversies in rendering this diagnosis, while highlighting the importance of a multidisciplinary approach to managing atypical thyroid nodules.

The Bethesda System for Reporting Thyroid Cytopathology: Validating at Tribhuvan University Teaching Hospital.

Introduction Fine needle aspiration cytopathology (FNAC) is widely used for the stratification of thyroid nodules. Objective The objective of the present study is to validate FNAC reporting based on The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) at our institution and to calculate the risk of malignancy in each category. Methods This was a descriptive cross-sectional study conducted jointly at the Department of Ear, Nose and Throat and at the Department of Pathology for a period of 1.5 years (May 2018 to November 2018). All cases presenting with thyroid swelling in the outpatient department were investigated with ultrasonography (USG) of the neck, thyroid function test, and FNAC. All FNAC reporting was done according to TBSRTC. Results A total of 134 thyroidectomies were performed during the study period. The female to male ratio was 5.3:1. The age ranged from 11 to 74 years old. with a mean age of 51 years old. The FNAC has a specificity of 84.9%, a sensitivity of 89.4%, a positive predictive value of 86.4%, a negative predictive value of 88.2%, and an accuracy of 87.3% in detecting thyroid cancer. The implied risk of malignancy (ROM) in Bethesda II, III, IV, V and VI is 11.7%, 25%,40%,76.6% & 96%, respectively. Conclusion The four studied categories had a ROM comparable to other studies, except for the Bethesda III category. Further studies with larger sample sizes and with the use of USG guidance for the aspiration from the thyroid swelling may give better results by reducing the number of false negative and false positive cases.

Application of the Bethesda system for reporting thyroid cytopathology for classification of thyroid nodules: A clinical and cytopathological characteristics in Bhutanese population.

The existence of baseline data on the spectrum of thyroid nodules in Bhutanese patients is unknown. Fine-needle aspiration cytology (FNAC) is regarded as the gold standard diagnostic test for pre-op assessment of thyroid lesions. We conducted a retrospective study, involving 765 patients who underwent FNAC of the thyroid gland, at Jigme Dorji Wangchuck National Referral Hospital, Thimphu, between January-2018 to December-2020. We aimed to assess the cytomorphological spectrum of thyroid nodules, classify them as per The Bethesda system for reporting thyroid cytopathology (TBSRTC), assess risk of malignancy (ROM), and evaluate the accuracy of FNAC in diagnosing thyroid malignancy. Colloid nodule (37.4%) and papillary thyroid carcinoma (4.2%) constituted the majority of benign and malignant cytological diagnoses, respectively. According to TBSRTC, majority of the cases (82.0%) fell under the Bethesda II category. Bethesda III was the least common (1.4%) category. As compared to histopathological diagnosis; the sensitivity, specificity, positive and the negative predictive values of FNAC in diagnosing thyroid malignancy were 90.0%, 93.3%, 93.10%, and 90.32% respectively. The ROM increased concurrently with the grade of the Bethesda category and was more or less close to the ROM reference range, published in the TBSRTC. Benign thyroid nodules (82.0%) constituted a majority of thyroid nodules in Bhutanese patients. FNAC was found to be reliable in detecting thyroid malignancy. From the literature, TBSRTC was found to be a more convenient method for reporting thyroid cytology. Henceforth, as most institutes, we plan to implement TBSRTC for reporting thyroid cytopathology.

RECLASSIFICATION OF THYROID LESIONS BASED ON THE BETHESDA SYSTEM BY FINE NEEDLE ASPIRATION CYTOLOGY: A 2 YEAR STUDY FROM A TERTIARY CARE CENTRE IN NORTH-EAST INDIA

Background: Thyroid gland is affected by a vast array of disorders like developmental, inflammatory, hyperplastic and neoplastic disorders. Both non-neoplastic and neoplastic diseases affect it and led to diffuse or nodular enlargement. FNAC is widely considered as the diagnostic technique of choice in the assessment of thyroid lesions. In the Bethesda system for reporting thyroid cytopathology (TBSRTC), the six diagnostic categories have been designated one to six roman numbers. A thyroid FNA specimen is considered to be satisfactory for evaluation (and benign), at least 6 groups of benign follicular cells are required, and each group composed of at least 10 cells. Methods: A two year retrospective cross sectional study was conducted. Patients attending cytology out-patient department, were the study population. Consent was obtained from all the patients before the start of the procedure. Twenty ml syringe with 24 gauge needle fitted in Cameco handle was used for aspiration. Prepared smears were stained with Giemsa stain. Any cystic fluid thus withdrawn from the swelling was centrifuged and the deposit was studied microscopically after spreading. Results: A total of 539 thyroid swelling were aspirated during the study period. Of 539 cases 88% of cases were reported in females and 12% of cases were reported in males. Ninety percentage of cases were reported under benign category. Twenty five(4.6%) cases were reported as malignant during the study period, out of which 23(4.2%) cases were reported as papillary carcinoma. Papillary carcinoma constitutes the most common malignant lesion reported during the study period. Conclusion: The Bethesda system provides a standardized nomenclature for thyroid cytopathology reporting with improved interobserver reproducibility. Facilitates better understanding between cytopathologist and clinicians for uniform and proper management. Key words: Thyroid, Fine needle aspiration cytology (FNAC), The Bethesda system.

Subclassification of the Bethesda Category III (AUS/FLUS): A study of thyroid FNA cytology based on ThinPrep slides from the National Cancer Center in China.

The atypia of an undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) category in the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) is a heterogeneous category, which includes various cell patterns. The subclassification of AUS/FLUS was suggested in the 2017 TBSRTC. However, the risk of malignancy (ROM) associated with different subgroups remains unresolved. Herein, AUS/FLUS aspirates were subclassified, from which the ROM of each subgroup was determined. All cases undergoing fine-needle aspiration (FNA) from July 2013 to December 2018 were reviewed. Of 12,913 thyroid FNAs, 1053 (8.2%) were AUS/FLUS. The slides of 222 patients with AUS/FLUS with surgical follow-up were reviewed and subclassified according to the recommendations of the 2017 TBSRTC. There were 195 aspirates consistently diagnosed as AUS/FLUS and subclassified as cytologic atypia 1 (AUS-C1); cytologic atypia 2 (AUS-C2); architectural atypia (AUS-A); cytologic and architectural atypia (AUS-C&A); Hürthle cell aspirates (AUS-H); atypia, not otherwise specified (AUS-NOS); and atypical lymphoid cells, rule out lymphoma (AUS-L). Malignancy was identified in 83.3% (185 of 222) of the AUS/FLUS nodules. The AUS-C1 group was the most common (62.1%), followed by the AUS-C&A (12.8%), AUS-C2 (10.8%), AUS-H (6.7%), AUS-NOS (5.6%), AUS-L (1.5%), and AUS-A (0.5%) groups. AUS-C1 had the highest ROM (92.6%) among the groups and varied significantly from that of the AUS-C&A (P = .171), AUS-C2 (P = .001), AUS-H (P = .001), and AUS-NOS (P < .001) groups. As a heterogeneous category of TBSRTC, the ROM for AUS/FLUS varies greatly among medical centers. Subclassification of AUS/FLUS might be helpful in identifying nodules with a high ROM in this category and improving the management of such nodules.

The Bethesda System for Reporting Thyroid Cytopathology: A Retrospective Review of its Diagnostic Utility at Johns Hopkins Aramco Healthcare, Saudi Arabia

PurposeFine needle aspiration (FNA) is the gold standard for assessment of thyroid nodules, with the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) used to predict the malignancy risk of these nodules. Our aim was to evaluate the diagnostic utility of the TBSRTC for a Saudi population, by comparing the malignancy risk based on histopathology to FNA-based diagnosis of each of the TBSRTC categories and to previously published malignancy risk in other population. Materials and methodsThis was a retrospective study of the data of 241 patients who underwent FNA assessment of thyroid nodules and surgical resection with histopathology at John Hopkins Aramco Healthcare, Dhahran, Saudi Arabia, between January 2016 and December 2019. ResultsThe malignancy risk for each of the TBSRTC categories was as follows: non-diagnostic, 25%, benign; 5.74%; atypia of undetermined significance, 37%; suspicious for follicular neoplasm, 38%; suspicious for malignancy, 100%; and malignant, 95%. Our finding were comparable to previously published malignancy risks, except for a higher rate of malignancy in the benign category at 18% compared to 0–3%. ConclusionOur findings validate the diagnostic reproducibility of the TBSRTC for a Saudi population, with the risk of malignancy confirmed by histopathological assessment being consistent with those previously reported for other populations.

A PROSPECTIVE STUDY FOR REPORTING THYROID FINE NEEDLE ASPIRATES BY THE BETHESDA SYSTEM WITH HISTOLOGICAL CORRELATION

BACKGROUND: To reduce ambiguity in diagnostic terminology in thyroid ne needle aspiration cytology (FNAC),The Bethesda System for Reporting Thyroid cytopathology (TBSRTC) system is a universal reporting system for standardization and could help in assessing the prognosis by estimating the malignant potential of each category . AIMS:The aim of the study is cytodiagnosis of thyroid ne needle aspirates and uniformity in the reporting as per Bethesda system. Histological examination was also conducted so that a correlation between cytodiagnosis and histopathological examination could be made. MATERIALS &amp; METHODS: This prospective study done on patients (125) presenting with thyroid swelling and advised for FNAC by clinicians, diagnosed according to the Bethesda system of thyroid cytopathology reporting . Then, correlation with histopathological report done in cases(55) in which surgery were done. RESULTS:The distribution of cases were as follows: 2 nondiagnostic(1.6%),89 cases(71.2%) were classied as benign, 6 cases (4.8%) were classied as atypia of undetermined signicance /follicular lesion of undetermined signicance/AFLUS, 7 cases(5.6%) were classied as follicular neoplasm/SFN, 3 cases( 2.4% ) were classied as suspicious, and 18 cases( 14.4%) were classied as malignant.In our study, rates of malignancy for each category are : nondiagnostic-0%, benign-4.76%, AFLUS- 16.67% ,SFN-28.57%, suspicious- 66.67% and malignant-94.12%.

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

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. 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"). 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. 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.

O31: CORRELATION BETWEEN THYROID FINE NEEDLE ASPIRATION CYTOLOGY (FNAC) SCORES AND CANCER INCIDENCE ON FINAL HISTOPATHOLOGY – A MULTI-CENTRE RETROSPECTIVE ANALYSIS

Abstract Introduction Fine Needle Aspiration Cytology (FNAC) is the best diagnostic tool for evaluating thyroid nodules pre-operatively. The Bethesda System for Reporting Thyroid Cyto-pathology (TBSRTC) in America and THY classification in Europe are standardized reporting systems for thyroid FNAC specimens using six categories. As compared to the first edition in 2009, a second edition of TBSRTC published in 2017 has revised risk of malignancy (ROM) for these categories, with focus on atypia of unknown significance (Thy3A) upgraded to 10-30% from previously 5-15%, and suspicion for follicular neoplasm (Thy3F) 25-40% from previous 15-30%. Method A three-year audit of thyroid surgeries performed in two high volume thyroid institutions from January 2016 to September 2019, was performed retrospectively. The FNAs were performed by thyroid specialist radiologists with a cytopathology technician in attendance for rapid on-site evaluation and reported as per TBSRTC and Thy classification, by a Consultant Cyto-pathologist from a single institution. Result A total of 702 patients were examined. There were 552 patients who had corresponding FNAC prior to surgery (mean age 53.6 years, females 79%). The rates of malignancy were, Thy1: 9.3%, Thy2: 4.6%, Thy3A: 10.8%, Thy3F: 28.7%, Thy4: 82.3% and Thy5: 100%. The main types of thyroid malignancy were Papillary (73.6%), Follicular (14.1%), Medullary (4%), Anaplastic (4.7%) and others (3.6%). Conclusion Pre-operative diagnosis of thyroid nodules using TBSRTC was comparable and the criteria helped avoid misinterpretation of results. Our results were comparable with the risk of malignancy in 2009 edition of TBSRTC, as compared to the 2017 revision. Take-home message Pre-operative diagnosis of thyroid nodules using The Bethesda System for Reporting Thyroid Cyto-pathology (TBSRTC) was comparable and the criteria helped avoid misinterpretation of results. Our results were comparable with the risk of malignancy in 2009 edition of TBSRTC, as compared to the 2017 revision.

The Use of the Bethesda System for Reporting Thyroid Cytopathology in Pediatric Thyroid Nodules: A Meta-Analysis.

Background: Little is known about the application of the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) in pediatric thyroid nodules. This meta-analysis was aimed to investigate the use of TBSRTC in the pediatric population. Methods: Relevant articles were searched in PubMed and Web of Science. Meta-analysis of proportion and its 95% confidence interval (CI) were computed utilizing the random-effect model. We used subgroup analyses and meta-regression to explore the sources of heterogeneities. Egger's regression test and funnel plot visualization were used to examine publication bias. Results: We included 17 articles comprising of 3687 pediatric thyroid nodules for meta-analyses. TBSRTC outputs including frequency and risk of malignancy (ROM) for the majority of categories were not statistically different from recently published meta-analysis of 145,066 thyroid nodules in adult patients. The resection rate (RR) in the pediatric group was significantly higher in most of the categories compared with published adult data: benign, 23.2% [CI = 18.6-27.9] vs. 13.0% [CI = 9.5-16.5]; atypia of undetermined significance/follicular lesion of undetermined significance, 62.6% [CI = 50.3-74.9] vs. 36.2% [CI = 29.9-42.5]; follicular neoplasm/suspicious for follicular neoplasm, 84.3% [CI = 75.2-93.4] vs. 60.5% [CI = 54.5-66.5]; and suspicious for malignancy, 93.8% [CI = 90.1-97.6] vs. 69.7% [CI = 64.0-75.5]. Conclusion: TBSRTC is a valuable tool to make clinical decisions for pediatric patients with thyroid nodules. Pediatric patients with benign and indeterminate thyroid nodules had a higher RR than adult counterpart, but ROM of these categories in adults and children was not statistically different suggesting a potential risk of overtreatment in pediatric patients. Determining the best treatment guidelines and additional tools for risk stratification must be a top priority to precisely identify the target patient groups for surgical intervention.

English

BACKGROUND Thyroid cancer has the most rapidly increasing incidence of all major cancers in India. The overall prevalence of thyroid malignancy is approximately 1 - 5 % of all cancers in women and less than 2 % in men. Thyroid nodules are a common clinical finding and have a reported prevalence of 4 – 7 % in the general population. The vast majority of these nodules are non-neoplastic or benign and the risk of malignancy varies from 5 to 10 %. Fine needle aspiration cytology (FNAC) is an efficient and reliable means for the evaluation of thyroid nodules. A key challenge for clinicians is to choose which thyroid nodule is to be investigated further and treated. Early detection and treatment of malignant thyroid nodules is associated with excellent outcomes. The aim of our study is to compare and correlate between fine needle aspiration cytology and histopathology of resected specimen and to determine the diagnostic accuracy of TBSRTC (The Bethesda System for Reporting Thyroid Cytopathology) in thyroid nodule. METHODS This is a cross sectional validation study conducted in a tertiary care hospital (R.G. Kar Medical College) of Kolkata to find the sensitivity, specificity and diagnostic accuracy of TBSRTC in evaluation of thyroid nodule. RESULTS We have observed that TBSRTC is highly sensitive and specific in stratifying the malignancy risk of thyroid nodule. CONCLUSIONS It aids the clinician to choose the thyroid nodules which require further evaluation and intervention. It also guides the clinician to decide the operability of thyroid nodule. TBSRTC is highly accurate and is highly specific in stratifying the risk of malignancy of thyroid nodule. KEYWORDS TBSRTC, FNAC, Thyroid Nodules, Thyroid Cancer

A Large Thyroid Fine Needle Aspiration Biopsy Cohort with Long-Term Population-Based Follow-Up.

Background: Prior studies evaluating thyroid fine needle aspiration biopsies (FNABs) have limited the calculation of risk of malignancy (ROM) to cytologic specimens with corresponding histologic specimens, and clinical follow-up for those patients who do not undergo immediate surgery has been largely disregarded. Moreover, there is marked variability in how researchers have approached thyroid FNAB statistical analyses. This study addresses the urgent need for information from a large cohort of patients with long-term clinical follow-up to more accurately determine the performance of thyroid FNAB and ROM for each diagnostic category. Methods: A retrospective review of the University of California, San Francisco (UCSF), pathology database for thyroid FNABs from January 1, 1997, to December 31, 2004, was performed. Diagnoses were coded using the 2017 The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC), and patients were matched to both the UCSF cancer registry and California Cancer Registry. Data were analyzed using the Kaplan-Meier method, and stratified by TBSRTC diagnostic category. Kaplan-Meier curves were used to estimate incidence rates of malignancy, stratified by FNAB category. Cox proportional hazards models were used to determine the instantaneous ROM. Results: Initial FNABs from 2207 patients were included. Median follow-up period after the first thyroid FNAB was 13.9 years (range: 10.5-18.4 years). During follow-up, there were 279 confirmed diagnoses of thyroid malignancy. Estimates derived from Kaplan-Meier curves demonstrated that the risk of having a thyroid malignancy was low for nondiagnostic and benign categories, intermediate for atypia of undetermined significance (AUS), follicular lesion of undetermined significance (FLUS), AUS/FLUS combined, and follicular neoplasm, and high for suspicious and malignant categories. A total of 52/1575 false-negative cases (3.2%) were identified. Excluding papillary microcarcinomas, the false-negative rate was 1.5% (23/1575). No patients with a false-negative diagnosis died of thyroid cancer during the follow-up period. Conclusions: Asymptomatic patients with low-risk clinical and radiologic features and initially benign or unsatisfactory biopsy are unlikely to develop thyroid malignancy and highly unlikely to die of thyroid cancer. FNAB is highly accurate in detecting malignancy. Additional studies evaluating similar large data sets after the adoption of TBSRTC and the integration of molecular testing are needed.