Preoperative diagnosis of thyroid nodules using the Bethesda System for Reporting Thyroid Cytopathology: a comprehensive review and meta-analysis

Abstract

Fine-needle aspiration biopsy (FNAB) is the test of choice for the evaluation of nodules, arriving at a cancer diagnosis, and guiding surgical management. This review and meta-analysis aims to objectively evaluate the Bethesda System for Reporting Thyroid Cytopathology (BSRTC) based upon literature reports of histopathological outcomes following cytopathological diagnoses. Thirteen studies were reviewed and the risk of malignancy (ROM) for each of the BSRTC diagnostic categories were calculated as: Non-diagnostic 11–26%, Benign 4–9%, AUS/FLUS 19–38%, FN/SFN 27–40%, SFM 50–79%, and Malignant 98–100%. In typical clinical utilization, the sensitivity and specificity of thyroid FNAB diagnosis using the BSRTC were 96% and 46%, respectively. The BSRTC represents an important advance in standardizing thyroid FNAB cytopathological reporting. Close attention should be paid to the observation that the AUS-FLUS and FN-SFN DCs have overlapping ROMs, and the potential clinical implications of this finding on patient management.

Keywords::

• Bethesda
• BSRTC
• cytology
• fine-needle biopsy
• needle biopsy
• thyroid cancer
• thyroid neoplasm

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Fine-needle aspiration biopsy is currently the best diagnostic test for the preoperative evaluation of a thyroid nodule.

• Clear communication of cytopathological results from the pathologist to the treating clinician(s) is of critical importance for optimal patient management.

• The Bethesda System for Reporting Thyroid Cytopathology (BSRTC) provides a well-defined framework for communicating cytopathological diagnoses from the pathologist to the clinician.

• The BSRTC consists of 6 diagnostic groups, each having an associated specific cancer risk, and estimates of these risks based upon clinical reports have been calculated in this review.

• The atypia of undetermined significance or follicular lesion of undetermined significance diagnostic group confers a cancer risk that is significantly higher than the cancer risk suggested by the BSRTC, and this finding must be considered when managing cases in this group.

• In typical clinical utilization, the BSRTC is highly sensitive (96%), but lacks specificity (46%) for thyroid cancer diagnosis.

• Decisions regarding the surgical management of cases with indeterminate cytopathology should incorporate the specific cytopathologic diagnosis, as well as other relevant clinical parameters.

• Ancillary tests for accurately diagnosing indeterminate cases are being actively investigated, and are currently available at select institutions, over time these modalities will become increasingly incorporated into the clinical management algorithm of thyroid nodules.

Notes

*The test characteristics for this specific scenario (positive test = Malignant or SFM or FN-SFN or AUS-FLUS) are presented here because these diagnoses are most likely to undergo surgery, based on data collected in this study.