Incidence and malignancy rates classified by The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) – An 8-year tertiary center experience in Thailand

Abstract

Incidence and Malignancy Rates Classified by The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) – An 8-year Tertiary Center experience in Thailand. Background Fine-needle aspiration (FNA) of the thyroid is considered the best diagnostic tool for preoperative evaluation of thyroid nodules. The introduction of T he B ethesda S ystem for R eporting T hyroid C ytopathology (TBSRTC) in 2010 provided the opportunity to establish worldwide standard for reporting and terminology guidelines for diagnostic categories. It is recommended that every institution evaluates the risk of malignancy (ROM) in each category for quality improvement process. Aim To assess the effectiveness of TBSRTC method at our institution using cyto-histological correlation. Method A retrospective 8-year (2010–2017) audit of thyroid FNA done by thyroid specialists at Theptarin hospital. The FNA results were classified according to TBSRTC. Histopathology reports for operated cases were used to correlate cytology and final histopathology. Results A total of 2735 thyroid FNA from 2115 patients (mean age 45.7 ± 13.1 years, female 89.8%) were examined. The rates of non-diagnostic, benign, atypia of undetermined significance (AUS), follicular neoplasm, suspected for malignancy, and malignant cases were 21.1%, 66.6%, 4.7%, 2.4%, 1.8%, and 3.3% respectively. There were 188 patients (9%) who underwent surgical resection with available histopathology. Malignancy rates in operated thyroid nodules were 20.0%, 4.2%, 9.4%, 23.5%, 57.1%, and 90.3% for categories 1 to 6, respectively. The sensitivity, specificity, negative predictive value, and positive predictive value were 96.6%, 88.5%, 95.8%, and 90.3, respectively. Conclusions Preoperative diagnosis of thyroid nodules using TBSRTC in our hospital was comparable with other studies. The uniform diagnostic criteria of the Bethesda System help avoid misinterpretation while sharing local experience with international benchmarks.

Comparison of the Clinical Validity of Droplet Digital PCR to ARMS‐PCR for BRAF V600E Mutation Detection in Thyroid Nodules

“…[19][20][21] Additionally, in this study, over half of thyroid nodules were classified in category I (undiagnosed) and II (benign) and the BRAF V600E mutation rates were 12% and 4%, respectively, with similar malignancy rates reported in previous studies. 21 in line with the fact that PTCs are most likely to occur in young women. 5 In the UK, it has been reported that the incidence rates of thyroid cancer in women reach a peak at ages 35-39 years and then decline steadily.…”

High risk of malignancy in cases with atypia of undetermined significance on fine needle aspiration of thyroid nodules even after exclusion of NIFTP

“…A 3 month waiting period prior to any repeat FNAC does not improve the diagnostic yield or alter patient care algorithm. 15,40 Malignancy and surgical procedure rates were found to be similar among patients who did or did not have a re-FNAC. 41 On the basis of these collective results, the question arises why the malignant tumors, that is, PTCs were missed on initial FNA.…”

“…As a result of these revised items, RoM of AUS/FLUS (including NIFTP) increased from 5%-15% to 10%-30% but remain relatively unchanged (6%-18%) if excluding NIFTP as a diagnosis of benign/nonmalignant thyroid condition. 15 The NIFTP concept was accepted and included into the latest version of the WHO classification of tumors of endocrine organs and the revised version of TBSRTC also took into account its presence, but did not create a specific diagnostic category for it, as NIFTP diagnosis is not possible on FNAC. 16 If cytopathology demonstrated AUS, clinical recommendations are for repeat FNAC evaluation under ultrasound (US) guidance, or lobectomy (especially if the nodule is large or if it has high-risk sonographic features.…”

“…TBSRTC was updated in 2017 to refine the category of AUS/FLUS by sub‐classifying this category regarding the presence or absence of nuclear atypia and also introduction of a new histopathological diagnosis of “noninvasive follicular tumor with papillary‐like nuclear features (NIFTP)”. As a result of these revised items, RoM of AUS/FLUS (including NIFTP) increased from 5%‐15% to 10%‐30% but remain relatively unchanged (6%‐18%) if excluding NIFTP as a diagnosis of benign/nonmalignant thyroid condition 15 …”

Incidence and Malignancy Rate of Bethesda Category III Thyroid Lesions in A Tertiary Hospital

“…Bethesda classification system gives six categories for thyroid lesions in order of increasing rate of malignancy. 1 Indeterminate lesion which are not clearly benign or malignant has been a walk on the fence for both clinicians and pathologist. Hence, the category III which is labelled as "Atypia of undetermined significance" / "follicular lesion of undetermined significance" is for separating lesions with insufficient degree of atypia to qualify for any of the suspicious categories.…”