Not All Bethesda 1 Thyroid Nodules Were Created Equal: Different B1 Subgroups

Area of Science:

• Endocrinology
• Cytopathology
• Oncology

Background:

• The Bethesda System for Reporting Thyroid Cytopathology provides standardized thyroid fine-needle aspiration (FNA) reporting.
• The Nondiagnostic/Unsatisfactory (B1) category within this system is known for variable malignancy risk.
• This variability suggests potential heterogeneity within the B1 category.

Purpose of the Study:

• To investigate if distinct subgroups within the B1 category (blood only, insufficient thyrocytes, cyst content) exhibit different rates of malignancy.
• To test the hypothesis that B1 subgroups possess varying malignancy risks.

Main Methods:

• Retrospective observational study of 154 patients with B1 thyroid FNA results from 2013-2018.
• Analysis of surgical outcomes to determine final malignancy status for each B1 subgroup.
• Calculation of malignancy rates for blood-only, thyrocyte-insufficient, and cyst-content subgroups.

Main Results:

• Malignancy rates were significantly higher in the Blood subgroup compared to other subgroups (P < .05).
• The Thyrocytes subgroup showed a higher malignancy rate than the Cyst subgroup (P < .05).
• All identified malignancies were papillary thyroid carcinomas; repeat FNAs often yielded different B1 subgroups.

Conclusions:

• The varying malignancy rates across B1 subgroups support the need for individualized patient management strategies.
• Recognizing and differentiating B1 subgroups can refine diagnostic and treatment pathways for thyroid nodules.