Overview of the Bethesda System for Reporting Thyroid Cytopathology

Abstract

The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) is the most widely used standardized system for reporting thyroid fine needle aspiration biopsy (FNAB) results and its use is endorsed by the American Thyroid Association (ATA). TBSRTC is a six- tiered scheme with evidence-based anticipated risk of malignancy and standard treatment approaches associated with each diagnostic category. The six categories in TBSRTC are nondiagnostic, benign, atypia (or follicular lesion) of undetermined significance (AUS/FLUS), suspicious for a follicular neoplasm (or follicular neoplasm) (SFN/FN), suspicious for malignancy, and malignant. Using this scheme, most thyroid FNABs are readily classified as being clearly benign or malignant. A small percentage of cases are classified in one of the “indeterminate” categories (AUS/FLUS, SFN/FN, suspicious for malignancy). Surgical management is the norm for patients with a diagnosis of suspicious for malignancy or malignant on FNAB. For low-risk indeterminate aspirates (AUS/FLUS, SFN/FN), management options are complex and include observation, repeat FNAB, molecular testing, and surgery.