Noninvasive follicular thyroid neoplasm with papillary-like nuclear features and the risk of malignancy in thyroid cytology: Data from Singapore

Introduction: The impact of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) on the risk of malignancy (ROM) in fine-needle aspiration cytology (FNAC) per The Bethesda System for Reporting Thyroid Cytopathology has not been well reported in Singapore. Methods: We retrospectively identified 821 thyroid nodules with preoperative FNAC from 788 patients out of 1,279 consecutive thyroidectomies performed between January 2010 and August 2016 in a tertiary general hospital in Singapore. Possible cases of NIFTP were reviewed for reclassification and the impact of NIFTP on ROM was analysed. Results: The incidence of NIFTP was 1.2% (10 out of 821). If NIFTP is considered benign, ROM in Bethesda I through VI were 8.6%, 3.5%, 26.3%, 20.0%, 87.7%, 97.0% versus 8.6%, 4.2%, 28.1%, 26.7%, 89.2% and 100% if NIFTP is considered malignant. Eight patients with NIFTP had follow-up of 15 to 110 months. One had possible rib metastasis as evidenced by I131 uptake but remained free of structural or biochemical disease during a follow-up period of 110 months. None had lymph node metastasis at presentation, nor locoregional or distant recurrence. Conclusion: Classifying NIFTP as benign decreased ROM in Bethesda II through VI, but the benignity of NIFTP requires more prospective studies to ascertain. The impact of NIFTP on ROM in our institution also appears to be lower than that reported in the Western studies Keywords: Bethesda, cytology, NIFTP, risk of malignancy, TBSRTC, thyroid nodule

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

<b><i>Background:</i></b> 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). <b><i>Methods:</i></b> 584 consecutive thyroid FNA specimens were collected and stratified by preparation type (ThinPrep [TP] vs. CS &amp; 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. <b><i>Results:</i></b> Of 584 thyroid FNA specimens, 73 (12.5%) and 511 (87.5%) were evaluated by TP only and CS &amp; 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 &amp; TP cohorts, 29 (39.7%) and 98 (19.2%) had subsequent resections, respectively. The frequency of non-diagnostic cases was lower in the CS &amp; 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 &amp; 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. <b><i>Conclusion:</i></b> 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.

Rate of malignancy for thyroid nodules with AUS/FLUS cytopathology in a tertiary care center – a retrospective cohort study

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

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.