Variability in the Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance Diagnosis in the Bethesda System for Reporting Thyroid Cytopathology: Sources and Recommendations

Abstract

Objective: Of the 6 categories in the Bethesda System for Reporting Thyroid Cytopathology (BSRTC), the atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) category has received the most attention. The objectives of this study were to review the use of the AUS/FLUS category in recent studies, to search for likely sources of the variability in its use, and to address possible methods for improvement. Study Design: A PubMed search was performed to retrieve peer-reviewed articles that have comprehensively detailed the incidence and outcome of AUS/FLUS and other BSRTC categories. Related thyroid cytology articles on the BSRTC were also included. Results: Recent series that reported experiences with the BSRTC categories showed that the AUS/FLUS category exhibited a marked variability in incidence (0.7–18%) and malignant outcome (6–48%) in resection specimens. Review of the literature revealed institutional differences in technical aspects, interpretation and application of criteria, analysis of outcome data, and clinicopathologic interactions. Conclusions: A heightened awareness of technical issues, diagnostic borders of AUS/FLUS, and clinical management may aid in diagnostic refinement and help avoid overuse of this category.

Introducing the reporting system for thyroid fine-needle aspiration cytology according to the new guidelines of the Japan Thyroid Association [Review]

“…Actually, Ohori and Schoedel pointed out in their report that there was an overlap between AUS and suspicious of malignancy [61]. Significant wide range (0.7-18%) for the use of AUS/ FLUS and varied risk (6-48%) of malignancy were reported in the literature [61]. Wu et al divided AUS into four subtypes which were AUS cannot exclude PTC, AUS cannot exclude follicular neoplasm, AUS cannot exclude Hurthle cell neoplasm and AUS not otherwise specified [47].…”

“…From their observation, emphasis can be placed on the fact that cytological observation alone successfully pointed out delicate differences, which might discriminate early-stage lowmalignancy, in the Bethesda system, because risk of malignancy in AUS was low (5-15%) and that in suspicious for malignancy was high (60-75%), in addition to the evidence that both categories contained mostly PTC-type malignancy. Actually, Ohori and Schoedel pointed out in their report that there was an overlap between AUS and suspicious of malignancy [61]. Significant wide range (0.7-18%) for the use of AUS/ FLUS and varied risk (6-48%) of malignancy were reported in the literature [61].…”

New Strategies in Diagnosing Cancer in Thyroid Nodules: Impact of Molecular Markers

“…It provides a definitive diagnosis of benign or malignant thyroid disease in most cases. However, in 20% to 30% of nodules, FNA cytology cannot reliably rule out cancer, and such cases are reported as indeterminate for malignancy (11,12). To provide uniform diagnostic criteria and better risk stratification, the National Cancer Institute Thyroid Fineneedle Aspiration State of the Science Conference held in Bethesda, Maryland, in 2007, offered a classification system for reporting thyroid cytology, which has been adopted by most large volume centers, referred to subsequently as the Bethesda system (12,13).…”

Determination of the ideal sampling technique to reduce repeated procedures:a comparative study including 393 fine-needle aspirations for thyroid nodules

“…The rate of adequacy varies widely in the literature (2,4,5,9,10,11,13,15). The range published by Ohori et al (15) is between 76% and 95%. An approximate rate could be accepted as 80% (4).…”