Non-diagnostic thyroid nodules after application of the Bethesda system: a study evaluating the interval for repeat aspiration for non-diagnostic results

Fine-needle aspiration cytology repetition in thyroid nodules with non-diagnostic findings or atypia of undetermined significance/follicular lesions of undetermined significance: Does time matters?

INTRODUCTION

After a nondiagnostic (ND) result or findings of atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS), the current recommendation is for fine-needle aspiration cytology (FNAC) of the thyroid nodule to be repeated after at least 3 months. The aim of this study was to evaluate whether the interval between FNACs has any influence on the final cytological diagnosis.

METHODS

This was a retrospective study including all patients who underwent FNAC for the first time between January 2016 and December 2019 with ND or AUS/FLUS cytological results and then underwent a second FNAC procedure. Demographic, clinical, ultrasound and cytological data were retrieved. 1,497 nodules were evaluated; 535 had a first FNAC result of ND or AUS/FLUS, and 246 of these were re-evaluated with a second FNAC. The cases were grouped according to the timing of the repeat FNAC in two different analyses: < vs. ≥ 3 months and < vs. ≥ 6 months after initial FNAC.

RESULTS

Two hundred forty-six repeat FNACs were performed in 186 patients (76% female, median age 59.5 years). Twenty-two of these procedures (8.9%) were performed within 3 months, and 115 (46.2%) within 6 months of the first FNAC. Second FNAC findings were ND in 121 (49.2%) cases, benign in 103 (41.9%), AUS/FLUS in 8 (3.3%), follicular neoplasm/suspicious follicular neoplasm in 9 (3.7%), suspicious malignancy in 4 (1.6%) and malignancy in 1 (0.4%). Early repetition of FNAC did not significantly influence the final cytological result (< 3 vs. ≥ 3 months, P=0.51; and < 6 vs. ≥ 6 months, P=0.20).

CONCLUSION

This study suggests that the interval in repeat FNAC procedures is not relevant to overall diagnostic performance.

Should we wait 3 months for a repeat aspiration in non-diagnostic/indeterminate thyroid nodules? A cancer centre experience

INTRODUCTION

The Bethesda System recommends repeat fine needle aspiration (rFNA) as a management option for nodules classified under the non-diagnostic (ND) and atypia of undetermined significance (AUS/FLUS) categories. We evaluated the impact of an rFNA in diagnostic resolution and the role of early (≤3 months) vs delayed (more than 3 months) rFNA of nodules initially diagnosed as ND and AUS/FLUS.

METHODS

We retrospectively collected all thyroid FNA performed in a 4-year period with repeat aspiration. For cases initially signed out as ND or AUS/FLUS, diagnostic resolution was defined as a change to a Bethesda System category other than these two on rFNA. Comparison and regression models were fitted to identify the impact of time of rFNA on diagnostic resolution.

RESULTS

In total, 184 cases were initially assigned as ND and 143 as AUS/FLUS, with overall diagnostic resolution rates for the reassessment of these nodules calculated at 70.1% and 62.9%, respectively. For ND cases, time of rFNA was not significantly associated with diagnostic resolution (P > .05). For AUS/FLUS nodules, however, repeat aspiration performed in more than 3 months after the initial diagnosis was 2.5 times more likely to achieve a resolution in diagnosis than early rFNA (P = .024).

CONCLUSIONS

Repeat aspiration of ND and AUS/FLUS nodules helped define diagnosis for the majority of cases, being highly effective in determining correct patient management. For AUS/FLUS nodules, repeat aspiration performed more than 3 months after the initial diagnosis was associated with a higher diagnostic resolution.

Usage and Diagnostic Yield of Fine-Needle Aspiration Cytology and Core Needle Biopsy in Thyroid Nodules: A Systematic Review and Meta-Analysis of Literature Published by Korean Authors

Objectives

The usefulness of core needle biopsy (CNB) for the diagnosis of thyroid nodules remains controversial, and preferences vary across hospitals. The purpose of this study was to assess the actual use of CNB in Korea and to analyze the advantages and disadvantages of CNB through a systematic review and meta-analysis of papers published by Korean authors.

Methods

A meta-analysis of full-text publications published in English presenting data from Korea retrieved from the Embase literature database was performed.

Results

CNB led to a significantly lower proportion of non-diagnostic results than fine-needle aspiration (FNA). However, the frequency of atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) did not decrease as a result of performing CNB in nodules with initial AUS/FLUS results, while it increased in consecutive cases. A subcategory analysis of AUS/FLUS showed that the increased frequency of AUS/FLUS findings on CNB was due to more frequent diagnoses of architectural atypia and follicular neoplasm, which resulted in a higher frequency of inconclusive findings in consecutive cases compared to FNA. Hospitals favoring CNB had a higher proportion of AUS/FLUS diagnoses. Although the complication rate did not differ significantly between CNB and FNA, serious complications of CNB did occur.

Conclusion

A reduced frequency of non-diagnostic results may be a definite advantage of CNB over FNA. However, the increased frequency of diagnoses of architectural atypia and follicular neoplasm should be considered when selecting CNB as a diagnostic tool.

The role of repeat fine needle aspiration in managing indeterminate thyroid nodules

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.

Malignancy Rates of Thyroid Cytology: Cyst Fluid Benign or Non-Diagnostic?

Background

We sought to investigate subgroup distribution using Bethesda classification and risks for malignancy. We also compared the malignancy risk of cases that were denoted as non-diagnostic due to cystic contents, with cases that were denoted as non-diagnostic due to presence of other features.

Material/Methods

The study included pathology test results of 1,440 thyroid nodule samples diagnosed using Bethesda classification. Results of 305 thyroidectomy excision specimens from these patients were also compared with cytology results to determine the frequency of malignancy. The non-diagnostic group was divided into two categories: those with cystic contents, and others. Malignancy rates were separately calculated for the two groups, and compared with the other classification groups.

Results

Distribution of malignancy rates by Bethesda classification were as follows: non-diagnostic 12.5% (6/48), benign 1.5% (3/198), atypia of undetermined significance/follicular lesion of undetermined significance (AFLUS) 9% (1/11), suspicious for follicular neoplasm (SFN) 37.5% (3/8), suspicious malignancy 70% (8/26), malignancy 100% (14/14).

Conclusions

Despite the limited number of cases, our study concluded that cystic content was closer to the benign category than the non-diagnostic category if the assessment was based on malignancy rates. In this group, similar to aspirations containing plenty of lymphocytes that indicates colloid or lymphocytic thyroiditis, it is still controversial whether criterion for adequacy of follicular epithelial cells should be sought, or if they should be regarded as benign in order to prevent unnecessarily performance of repeat aspirations.