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The role of repeat fine needle aspiration in managing indeterminate thyroid nodules
Laura Allen1, Ayham Al Afif2, Matthew H Rigby2
1Faculty of Medicine, Dalhousie University, 1459 Oxford Street, Halifax, Nova Scotia, B3H 4R2, Canada.
Insights
Repeat fine needle aspiration (rFNA) for thyroid nodules with initial Bethesda category I or III results offers a definitive diagnosis in only 40% of cases. Malignancy rates for these categories were higher than predicted, impacting clinical management decisions.
Area of Science:
- Endocrinology
- Cytopathology
- Oncology
Background:
- The Bethesda System for reporting thyroid fine needle aspiration (FNA) cytology recommends repeat FNA (rFNA) for indeterminate results (Category I or III).
- The diagnostic utility and impact of rFNA on clinical management remain incompletely understood.
- This study investigates the value of rFNA for thyroid nodules classified as Bethesda Category I or III.
Purpose of the Study:
- To evaluate the diagnostic yield of repeat fine needle aspiration (rFNA) for thyroid nodules initially classified as Bethesda Category I or III.
- To determine the rate of definitive diagnoses obtained through rFNA.
- To assess the malignancy rates associated with Bethesda Category I and III thyroid nodules.
Main Methods:
- Retrospective chart review of patients with Category I or III thyroid FNA results undergoing rFNA between 2013-2015.
- Data collected included initial FNA results, ultrasound characteristics, rFNA findings, demographics, surgical details, and final pathology.
- Analysis focused on the diagnostic information gained from rFNA and subsequent management.
Main Results:
- Of 237 patients, 60% of rFNAs yielded a different cytological category, but 60% remained indeterminate (Category I or III).
- Definitive diagnoses (benign or malignant) were achieved in 40% of rFNA cases.
- Surgery was performed in 27% of patients; 46% of surgically resected nodules were malignant, with higher rates for Category I (32%) and III (42%) rFNA results than predicted.
Conclusions:
- Repeat FNA for Bethesda Category I and III thyroid nodules provides a definitive diagnosis in a limited 40% of instances.
- Malignancy rates observed in this cohort for Category I and III nodules exceeded Bethesda predictions.
- Clinical decisions for these indeterminate thyroid nodules should incorporate institution-specific malignancy data, patient factors, and ultrasound findings.
Background:
The Bethesda System is the most widely used for reporting fine needle aspiration (FNA) cytology. It recommends a repeat FNA (rFNA) when initial results are category I or III. It is unclear how often rFNA provides additional diagnostic information. We sought to investigate its utility at our institution.
Methods:
A retrospective chart review was performed of patients who had a category I or III FNA result and underwent rFNA of the same thyroid nodule between 2013 and 2015 at the QE II Health Sciences Centre in Nova Scotia, Canada. Results of initial FNA and ultrasound characteristics, rFNA, demographic data, surgical details, and pathology were collected.
Results:
A total of 237 patients (474 thyroid FNAs) were included. Most initial FNAs were category I (82%), the remainder category III (18%). rFNA yielded a different category 60% of the time. However, 60% remained category I or III. rFNA results of benign or malignant were found in 40% of cases; 1% were SFN/SFM. Twenty-seven percent of patients had surgery after rFNA; of those 68% had category I or III rFNA results. Of all nodules that underwent surgery, 46% were malignant, including 32% with category I rFNA results, and 42% category III.
Conclusions:
rFNA for category I and III nodules provided a definitive diagnosis in only 40% of cases, which is important for patient counseling. Malignancy rates at our centre were higher for these categories than predicted by Bethesda. Clinical management should consider institution specific malignancy rates, patient factors, and ultrasound findings.
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