Evaluation of thyroid nodules classified as Bethesda category III on cytology and their malignancy rate: An institutional experience

Abstract

Background: Thyroid gland nodules are common and fine-needle aspiration (FNA) is the gold standard for screening those nodules. The Bethesda system for reporting thyroid cytolopathology standardized reporting thyroid nodules aspirations, but atypia of undetermined significance or follicular lesion of undetermined significance (Bethesda category III) was the most controversial category. The aim of our study is to review our institutional experience and analyze the clinical implications of making a diagnosis of AUS/FLUS (Bethesda category III). Methods: This is a retrospective study of an 889 thyroid FNAs from 825 patients in Salmaniya Medical Complex, during (January 2013–December 2017). Results: The most common cause for designating cases as AUS/FLUS (Bethesda category III) was the presence of features suggestive of papillary thyroid carcinoma, but not quite fulfilling the criteria for such diagnosis. Ninety-six cases were diagnosed as AUS/FLUS (10.7%), in which 26 (27%) patients underwent surgery without repeating the FNA, 25 (26%) underwent a second FNA and 43 (44.7%) patients were followed up by ultrasound. On repeating the FNA, 1 (4%) was unsatisfactory, 13 (52%) were benign, 10 (40%) were AUS/FLUS, and only 1 (4%) was categorized as malignant. Thirty cases were surgically excised, in which 4 (13.3%) were diagnosed as follicular adenoma, 2 (6.6%) as Hurthle cell adenoma, 9 (30%) as multinodular goiter, 5 (16.6%) as multinodular goiter with Hashimoto thyroiditis, 1 (3.3%) as colloid nodule with Hashimoto thyroiditis, and 9 (30%) as papillary thyroid carcinoma. Among all the cases diagnosed initially as AUS/FLUS (Bethesda category III), 9 (9.3%) cases were diagnosed as papillary thyroid carcinoma. Conclusion: Diagnostically, we almost meet the international standards of designating cases with AUS/FLUS (Bethesda category III) and approximate the risk of malignancy. However, the clinical management's guidelines should be followed to decrease the risk of unnecessary surgeries and their complications. There is a statistically significant correlation between the age and gender with the final histopathology report, respectively.

Risk Stratification of Thyroid Nodules with Bethesda III Category: The Experience of a Territorial Healthcare Hospital

“…Several studies have indicated the AUS/FLUS diagnostic group has posed an ongoing challenge in terms of clinical management [3,5]. Although several patients with AUS/FLUS BSRTC diagnosis undergo a repeat FNAB, wide research has been done focusing on the application of adjunctive molecular testing to enable suitable clinical management.…”

“…The Bethesda system accepted to report thyroid cytopathology standardized the reports of TN aspirations; however, the category that attracted the greatest controversy was AUS/FLUS (Bethesda category III) [3,5]. This occurred because follicular lesions without nuclear atypia (i.e., FLUSs) and lesions with nuclear atypia were both integrated into a follicular or a nonfollicular pattern (i.e., AUS) [3,5]. In studies done prior, the AUS/FLUS category in FNAC has been reported to pose the greatest challenge; while the malignancy risk in AUS/FLUS has been estimated in BSRTC to hover between 5% and 15%, institutional data have revealed wide variations [6].…”

The Correlation of Age with Prognosis of Atypia of Undetermined Significance and Follicular Lesion of Undetermined Significance in Thyroid Nodules

“…However, among these six categories of TBSRTC, further management is still complicated for the third category. 5 , 6 This category contains heterogeneous lesions assigned to two subgroups: atypia of undetermined significance (AUS) and follicular lesion of undetermined significance (FLUS). 3–6 The prevalence of malignancy within this category ranges from 5% to 37%.…”

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

“…The objective of TBSRTC was to standardize the reporting of FNAC findings and thereby facilitate the communication of results between pathologists and treating physicians that are unambiguous and clinically helpful. Since its inception, it has been demonstrated that TBSRTC improves the quality of FNAC reporting, reducing ambiguous diagnoses and decreasing surgery rates for benign lesions 10 …”

“…Since its inception, it has been demonstrated that TBSRTC improves the quality of FNAC reporting, reducing ambiguous diagnoses and decreasing surgery rates for benign lesions. 10 One of the most important features of TBSRTC was the creation of category III. However, the "atypical" category ("atypia of undetermined significance" [AUS] or "follicular lesion of undetermined significance" [FLUS]) continues to cause diagnostic and therapeutic dilemmas.…”