The atypical thyroid fine-needle aspiration: past, present, and future

Area of Science:

• Cytopathology
• Endocrinology
• Surgical Pathology

Background:

• Thyroid fine-needle aspiration (FNA) is a primary diagnostic tool for thyroid nodules.
• Interpreting thyroid aspirates with subtle abnormalities poses challenges.
• The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) introduced the atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) category.

Purpose of the Study:

• To review cytomorphologic features of AUS/FLUS thyroid aspirates.
• To summarize research findings on AUS/FLUS cases since TBSRTC implementation.
• To enhance the clinical utility of the AUS/FLUS classification.

Main Methods:

• Literature review of studies on thyroid FNA and TBSRTC.
• Analysis of cytomorphologic criteria for AUS/FLUS classification.
• Synthesis of outcomes from studies evaluating AUS/FLUS cases.

Main Results:

• The AUS/FLUS category provides a systematic approach to borderline thyroid FNA results.
• Specific cytomorphologic features are associated with the AUS/FLUS diagnosis.
• Studies since TBSRTC implementation show varying malignancy rates for AUS/FLUS.

Conclusions:

• The AUS/FLUS category in TBSRTC is vital for managing ambiguous thyroid nodules.
• Understanding cytomorphologic features improves AUS/FLUS interpretation accuracy.
• Further research is needed to refine AUS/FLUS management strategies.