The Bethesda System for Reporting Thyroid Cytology (TBSRTC): From look‐backs to look‐ahead

Abstract

The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) was formalized in October 2007 by experts in thyroidology at the National Institute of Health in Bethesda, Maryland. The first edition of the TBSRTC book was published in 2010 and the second edition in 2018. The TBSRTC is widely employed in cytology practices in the United States and has also served as a model for similar tiered classification schemes for reporting thyroid cytopathology specimens. The tremendous success of TBSRTC cannot be underscored, it has provided a diagnostic framework which is well aligned with the present and the future of thyroid nodule management.

Contemporary Thyroid Nodule Evaluation and Management

“…The robust diagnostic framework provided by the BSRTC offers valuable guidance in developing management strategies for patients with thyroid nodules ( 53 ). Nonetheless, several potential diagnostic pitfalls exist that can lead to false-positive, false-negative, nondiagnostic, or indeterminate results ( 54 ).…”

“…Thyroid cytology can be considered only a screening test for these follicular-patterned lesions, the results of which will almost invariably reported as “indeterminate,” that is, assigned to Bethesda class III (“atypia of undetermined significance” or “follicular lesions of undetermined significance”) or IV (“follicular neoplasm or suspicious for a follicular [or Hürthle cell] neoplasm”). For most papillary thyroid cancers, as well as medullary, poorly differentiated, and undifferentiated carcinomas, the cytology report will usually be unambiguously diagnostic (Bethesda class VI, malignant), whereas some degree of uncertainty persists for nodules assigned to Bethesda class V (suspicious for malignancy) nodules, which is associated with a very broad range of malignancy risks ( 53 ).…”

Categorical systems for reporting of cytology specimens: Following the footsteps ofBethesda‐likereporting systems

“…The review by Baloch and LiVolsi 2 places the Bethesda System for Reporting Thyroid Cytology (BSRTC) in its historical context, as well as looking ahead to developments in thyroidology and how they pertain to classification systems for thyroid fine‐needle aspiration biopsies (FNABs). The authors review how the BSRTC was proposed during a particularly advantageous time when multiple new practice paradigms were proposed for the diagnosis and clinical management of thyroid nodules.…”

“…Baloch and LiVolsi 2 document follow‐up studies pertaining to the utility of the original BSRTC, including assessment of malignancy risk. Importantly, the authors address problems that were recognized following widespread acceptance of the system, which led to questioning the validity of some portions of the BSRTC.…”

Molecular tests for surgery indication in thyroid nodules: Should Bethesda V cytology be included?

“…Baloch and LiVolsi also recognize the importance of combined analysis of cytology, ultrasonography, and molecular profile. 1 In fact, clinical and ultrasonographic data should be taken into consideration even in the case of categories B-III and B-IV for which molecular tests are consensually recommended. When these data indicate a very high risk of malignancy (ROM), the negative predictive value (NPV) may not be sufficient to rule out the need for surgery.…”