Outcomes of the Bethesda system for reporting thyroid cytopathology: Real-life experience

Do large thyroid nodules (≥4 cm) without suspicious cytology need surgery?

Background

Fine-needle aspiration biopsy (FNAB) is a good diagnostic tool for thyroid nodules; however, its high false-negative rate for giant nodules remains controversial. Many clinicians recommend surgical resection for nodules >4 cm owing to an increased risk of malignancy and an increased false-negative rate. This study aimed to examine the feasibility of this approach and investigate the incidence of malignancy in thyroid nodules >4 cm without suspicious cytology based on medical records in our center.

Methods

This was a retrospective analysis of 453 patients that underwent preoperative FNAB for nodules measuring >4 cm between January 2017 and August 2022 at Severance Hospital, Seoul.

Results

Among the 453 patients, 140 nodules were benign and 119 were indeterminate. Among 259 patients, the final pathology results were divided into benign (149) and cancerous (110) groups, and the prevalence of malignancy was 38.9% in the benign group and 55.5% in the indeterminate group. Among the malignancies, follicular carcinoma and follicular variants of papillary carcinoma were observed in 83% of the cytologically benign group and 62.8% of the indeterminate group.

Conclusion

Preoperative FNAB had high false-negative rates and low diagnostic accuracy in patients with thyroid nodules >4 cm without suspicious cytologic features; therefore, diagnostic surgery may be considered a treatment option.

The clinical significance of the American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS) category 5 thyroid nodules: Not as risky as we think?

BACKGROUND

Although the prevalence of thyroid nodules is high, few prove to be malignant. Based on sonographic features, the American College of Radiology Thyroid Imaging Reporting and Data System categorizes malignancy risk of thyroid nodules with associated management recommendations for each category level. Malignancy rates among nodules with a highly suspicious Thyroid Imaging Reporting and Data System category 5 warrant examination in the context of additional risk stratification tools, including cytopathology and molecular testing.

METHODS

All patients who underwent fine-needle aspiration biopsy for Thyroid Imaging Reporting and Data System category 5 nodules from January 2018 to September 2021 in a large integrated academic health system were reviewed. Using the Bethesda System for Reporting Thyroid Cytopathology, categories V and VI were set as malignant. Molecular testing (ThyroSeq version 3; Rye Brook, NY) yielding ≥50% risk of malignancy was deemed positive and correlated with surgical pathology.

RESULTS

A total of 496 Thyroid Imaging Reporting and Data System category 5 nodules were identified. On fine-needle aspiration cytopathology, 61 (12.3%) were malignant. The breakdown included Bethesda System for Reporting Thyroid Cytopathology I, 15 (3%); II, 362 (73%); III, 52 (10.5%); IV, 5 (1%); V, 6 (1.3%); and VI, 55 (11.1%). Of Bethesda System for Reporting Thyroid Cytopathology III/IV nodules with molecular testing (n = 53), 24.5% yielded positive results. In total, 42 (8.5%) nodules underwent surgical resection, most of which were Bethesda System for Reporting Thyroid Cytopathology VI (n = 26, 61.9%). Of excised nodules, 33 (78.6%) nodules were malignant, 6 (14.3%) benign, and 3 (7.1%) noninvasive follicular thyroid neoplasm with papillary-like nuclear features. All Thyroid Imaging Reporting and Data System category 5 nodules with malignant cytology (Bethesda System for Reporting Thyroid Cytopathology V/VI) that underwent surgery were malignant on histopathology. On average, the total Thyroid Imaging Reporting and Data System points were higher in malignant nodules compared with benign (9.3 vs 7.3; P = .015). Moreover, benign nodules more frequently received Thyroid Imaging Reporting and Data System points when the radiologist was unable to determine composition or echogenicity (33% vs 3% among malignant nodules; P = .01).

CONCLUSION

Thyroid Imaging Reporting and Data System category 5 designation in thyroid nodules is associated with a lower risk of malignancy than previously reported. Benign and malignant nodules with Thyroid Imaging Reporting and Data System category 5 designation have discrepancies in certain Thyroid Imaging Reporting and Data System characteristics and individual points assigned, which may offer an opportunity for quality improvement and standardization measures in ultrasound reporting practices.

Diagnostic value of thyroid imaging reporting and data system combined with BRAFV600E mutation analysis in Bethesda categories III-V thyroid nodules

Fine needle aspiration biopsy is a crucial method for preoperative diagnosis of thyroid nodules. However, thyroid nodules classified as Bethesda categories III–V cannot obtain definite cytological results. Our aim was to study the diagnostic value of thyroid imaging reporting and data system combined with BRAF^V600E mutation analysis in Bethesda categories III–V thyroid nodules, so as to provide more precise direction for the follow-up treatments. A total of 174 Bethesda categories III–V thyroid nodules performed TIRADS and BRAF^V600E mutation analysis were included in the study. We retrospectively analyzed the ultrasound features as well as the results of BRAF^V600E mutation of the 174 thyroid nodules. In the multiple regression analysis models, ultrasound features including lobulated or irregular margin, punctate echogenic foci, and shape with taller-than-wide were statistically significant in malignant nodules (p < 0.05). The area under the curve of the combination of TIRADS and BRAF^V600E increased to 0.925, which were much higher than TIRADS (0.861) and BRAF^V600E (0.804) separately. Combined diagnosis was of the greatest value to identify Bethesda III–V thyroid nodules definitely, especially with higher sensitivity (93%) and accuracy (90%).

Suspicious thyroid nodules ≥4 cm require diagnostic lobectomy regardless of their benign fine needle aspiration results

BACKGROUND/OBJECTIVE

The diagnostic accuracy of fine needle aspiration biopsy (FNAB) seems limited in large thyroid nodules with Bethesda Cat. 2 result. We aimed to determine the incidence of carcinoma with benign cytology and the reason for the high false-positive rate in thyroid nodules ≥4 cm.

METHODS

The records of 103 patients with thyroid nodules ≥4 cm with preoperative cytological diagnosis of Bethesda Cat. 2 who underwent thyroidectomy were consecutively reviewed. Characteristics between patients with malignant vs. benign pathology were compared.

RESULTS

Forty patients (38.8%) had malignancy. Malignancy was subclassified into follicular variant of papillary thyroid carcinoma (43%), minimally invasive follicular thyroid carcinoma (20.0%), and minimally invasive Hurthle cell thyroid carcinoma (10.9%). Patients with malignant cytology had significantly more suspicious ultrasound findings than those with benign cytology (p = 0.001).

CONCLUSIONS

Preoperative FNAB showed high false-negative rates in patients with thyroid nodules ≥4 cm with benign cytology. These nodules have a high malignancy rate with suspicious ultrasound findings.

Thyroid malignancy rates according to the Bethesda reporting system in Israel - A multicenter study

INTRODUCTION

The Bethesda System for Reporting Thyroid Cytopathology was developed in 2007 to facilitate an accurate, reproducible communication of thyroid fine-needle aspiration (FNA) interpretations between clinicians and cytopathologists and to serve as a guide for treatment. Based on large patient series, the system details the risk of malignancy for each category as well as a suggested management for each FNA result. Though this system has been widely adopted, there are only few studies to determine whether results are applicable for Israel.

METHODS

A multicenter, retrospective analysis of medical charts of all patients who underwent thyroid surgery between January 1st, 2012 and December 31st, 2016 in four medical centers in Israel was performed. Data was analyzed for the overall risk of malignancy for the Bethesda system groups as well as comparison between the different laboratories performing the test.

RESULTS

Records of 810 thyroidectomies in which preoperative cytological reports and final pathology were available and reviewed. The malignancy rates according to the Bethesda groups' I-VI for our cohort were: 27.8%, 17.6%, 41.4%, 41.4%, 86.9%, and 98.1% respectively. Similar results were seen when results were analyzed according to the different laboratories performing the tests.

CONCLUSIONS

Post-surgical review of all Bethesda groups had higher malignancy rates than those reported in the original report. These results indicate a difference in the malignancy rates for the different Bethesda system groups in Israel compared to those reported. Physicians are encouraged to use data validated for their own country or patients' community in addition to published values.