Journal of the American Society of Cytopathology
CommunicationThe 2017 Bethesda System for Reporting Thyroid Cytopathology
Introduction
With its inception, The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) established a standardized reporting system with a limited number of diagnostic categories for thyroid fine-needle aspiration (FNA) specimens. Using TBSRTC, cytopathologists can communicate their interpretations to the referring physician in terms that are succinct, unambiguous, and clinically useful.1, 2, 3
TBSRTC has been widely adopted in the United States and in many places worldwide and has been endorsed by the American Thyroid Association.4 It has improved communication and provided a uniform template for sharing data among investigators. Since its acceptance in clinical practice, however, questions have arisen over the proper use of the diagnostic categories, the associated risks of malignancy, and the appropriate management. By 2016 the time had come to consider revisions. The 2017 revision described herein was inspired by new data and new developments in the field of thyroid pathology: revised guidelines for the management of patients with thyroid nodules,4 the introduction of molecular testing as an adjunct to cytopathologic examination, and the reclassification of the non-invasive follicular variant of papillary thyroid carcinoma as non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP).5 Much of the groundwork for this revision was laid down by a symposium entitled “The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC): Past, Present, and Future” at the 2016 International Congress of Cytology in Yokohama, Japan. Preparations for the symposium began 12 months earlier with the designation of a steering group and the appointment of an international panel of 16 cytopathologists and an endocrinologist whose task was to review and summarize the published literature in English since the introduction of TBSRTC.
The symposium, moderated by Drs. Syed Ali and Philippe Vielh, took place on May 30, 2016, and the discussions and recommendations from the symposium have been summarized in a publication by Pusztaszeri et al.6 Based on the panel's recommendation, the 6 original general categories (“Nondiagnostic/Unsatisfactory [ND/UNS],” “Benign,” “Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance [AUS/FLUS],” “Follicular Neoplasm/Suspicious for a Follicular Neoplasm [FN/SFN],” “Suspicious for Malignancy [SUS],” and “Malignant”) have been retained in the 2017 revision, and a revised atlas is in press, with updated and expanded chapters devoted to these categories and refined definitions, morphologic criteria, and explanatory notes.7
Section snippets
Format of the report
For clarity of communication, the 2017 BSRTC continues to recommend that each report begin with a general diagnostic category. Because they are more ambiguous and less clearly descriptive, numerical designations alone (eg, “Bethesda III”) are discouraged for the purposes of cytologic reporting, although the numerical designations may be used in conjunction with the category name—for example, “Atypia of Undetermined Signficance (Bethesda III).”
The 6 general diagnostic categories are unchanged
Highlights of the 2017 Bethesda System for Thyroid Cytopathology
The original 6 categories remain unchanged, but a number of enhancements have been introduced with the 2017 BSRTC:
- 1.
The risks of malignancy have been recalculated based on post-2010 data.
- 2.
The risks of malignancy are shown two ways (see Table 2): (1) when NIFTP is not considered a malignancy; and (2) when NIFTP is still included among the “carcinomas.” The higher risk estimates may have more clinical relevance because they are defined for surgical disease.
- 3.
The “usual management” of AUS/FLUS and
Acknowledgments
The authors thank Dr. Erik Alexander for his review of the manuscript and helpful comments.
References (23)
- et al.
Evidence for overestimation of the prevalence of malignancy in indeterminate thyroid nodules classified as Bethesda category III
Surgery
(2015) - et al.
Factors that predict malignant thyroid lesions when fine-needle aspiration is “suspicious for follicular neoplasm”
Mayo Clinic Proc
(1997) - et al.
The Bethesda System for Reporting Thyroid Cytopathology
Thyroid
(2009) - et al.
The Bethesda System For Reporting Thyroid Cytopathology
Am J Clin Pathol
(2009) - et al.
The Bethesda System for Reporting Thyroid Cytopathology: Definitions, Criteria and Explanatory Notes
(2009) - et al.
2015 American Thyroid Association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer: The American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer
Thyroid
(2016) - et al.
Nomenclature revision for encapsulated follicular variant of papillary thyroid carcinoma: a paradigm shift to reduce overtreatment of indolent tumors
JAMA Oncol
(2016) - et al.
The Bethesda System for Reporting Thyroid Cytopathology: proposed modifications and updates for the second edition from an international panel
Acta Cytol
(2016) - et al.
The Bethesda System for Reporting Thyroid Cytopathology: Definitions, Criteria, and Explanatory Notes
(2018) Histologic follow-up of nondiagnostic thyroid fine needle aspirations: implications for adequacy criteria
Diagn Cytopathol
(2012)
Adequacy criteria for thyroid FNA evaluated by ThinPrep slides only
Cancer
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This article is being published jointly in Thyroid and Journal of the American Society of Cytopathology.