Clinical management of thyroid aspirates diagnosed as atypia of undetermined significance in the Philippines

An economically efficient strategy for diagnosing atypia of undetermined significance or follicular lesion of undetermined significance thyroid nodules with ultrasound-based risk stratification systems and BRAFV600E testing

Background

The management of thyroid nodules classified as atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS) has been a subject of ongoing debate. Therefore, the aim of this study was to investigate a cost-effective approach for managing these nodules by combining BRAFV600E mutation analysis with the guidelines provided by the American Thyroid Association (ATA) or the American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TIRADS).

Methods

This study included 762 AUS/FLUS nodules in 551 patients with a postoperative pathology. A preoperative BRAFV600E gene test and an evaluation using the ATA guidelines and ACR-TIRADS were performed. Two combined diagnostic approaches were employed: In method 1, all nodules underwent BRAFV600E gene testing, and nodules testing positive for BRAFV600E or for risk stratification systems (RSSs) were diagnosed as malignant, while those with negative results in both tests were considered benign. In method 2 (modified combination method), nodules were reclassified into low-risk (category 2 and 3 in the ATA guidelines and ACR-TIRADS), medium-risk (category 4), and high-risk (category 5) groups based on the malignancy rate of the RSSs. BRAFV600E gene testing was applied only with the medium-risk group. Nodules with positive BRAFV600E mutation were upgraded to the high-risk group, while negative cases remained in the medium-risk group.

Results

Both malignancy rates and positive BRAFV600E mutation rates increased with the increase in RSS category (P<0.001). The combination of ACR with BRAFV600E gene testing significantly improved the area under the curve (AUC) compared to the use of ACR or BRAFV600E alone (the AUCs for ACR combined with BRAFV600E, modified ACR combined with BRAFV600E, ACR alone, and BRAFV600E alone were 0.875, 0.878, 0.832, and 0.839, respectively; P<0.05 for both combinations vs. ACR or BRAFV600E alone). Similarly, ATA combined with BRAFV600E showed significant improvements in AUC compared to ATA alone (the AUCs for ATA combined with BRAFV600E, modified ATA combined with BRAFV600E, and ATA alone were 0.851, 0.846, 0.809, respectively; P<0.001 for both combination methods vs. ATA alone), but there was no significant difference observed compared to using BRAFV600E alone (P=0.450 and P=0.680 for both combination methods vs. BRAFV600E). Notably, the AUC of ACR combined with BRAFV600E was greater than that of ATA combined with BRAFV600E (P=0.047 and P=0.007 for both combination methods, respectively). There were no significant differences in diagnostic performance between the two combination approaches (P=0.428 for ACR combined with BRAFV600E and P=0.314 for ATA combined with BRAFV600E). Performing BRAFV600E gene testing only on the medium-risk groups (modified combination method) significantly reduced the rate of BRAFV600E gene testing (P<0.001) without increasing the false-negative rate (P=0.818 and P=0.394 for ACR and ATA, respectively).

Conclusions

Incorporating the BRAFV600E gene test exclusively for nodules in the medium-risk group significantly improved diagnostic efficacy, reduced the utilization of gene tests, and maintained a consistent false-negative rate.

The Asian Thyroid Working Group, from 2017 to 2023

The Asian Thyroid Working Group was founded in 2017 at the 12th Asia Oceania Thyroid Association (AOTA) Congress in Busan, Korea. This group activity aims to characterize Asian thyroid nodule practice and establish strict diagnostic criteria for thyroid carcinomas, a reporting system for thyroid fine needle aspiration cytology without the aid of gene panel tests, and new clinical guidelines appropriate to conservative Asian thyroid nodule practice based on scientific evidence obtained from Asian patient cohorts. Asian thyroid nodule practice is usually designed for patient-centered clinical practice, which is based on the Hippocratic Oath, "First do not harm patients," and an oriental filial piety "Do not harm one's own body because it is a precious gift from parents," which is remote from defensive medical practice in the West where physicians, including pathologists, suffer from severe malpractice climate. Furthermore, Asian practice emphasizes the importance of resource management in navigating the overdiagnosis of low-risk thyroid carcinomas. This article summarizes the Asian Thyroid Working Group activities in the past 7 years, from 2017 to 2023, highlighting the diversity of thyroid nodule practice between Asia and the West and the background reasons why Asian clinicians and pathologists modified Western systems significantly.

Malignancy in Thyroid Nodules with Bethesda III Category on Repeat Fine Needle Aspiration Biopsy

Objectives

This study aimed to evaluate the risk of malignancy for nodules repeatedly classified as Bethesda category III on fine needle aspiration biopsy (FNAB).

Methodology

A chart review on a series of 59 patients seen with thyroid nodules who underwent both initial and repeat FNAB at the Diabetes, Thyroid and Endocrine Center of St. Luke's Medical Center, Quezon City was conducted. The Thyroid Registry was utilized to collect each patient's demographic and clinical characteristics, ultrasonographic features of thyroid nodules along with the cytopathologic and histopathologic results. The subclassification of atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) were retrieved from the cytopathology reports using the institution's electronic Healthcare-Results Management System.

Results

A total of 59 adult patients with thyroid nodules were included. Nodules which were initially AUS/FLUS turned out to be malignant on repeat FNAB in 38 patients with a prevalence of 64.41% (95% CI: 50.87-76.45%). There was no significant difference with regards to clinical, ultrasonographic and cytopathologic features of malignancy between benign and malignant nodules.

Conclusion

Findings of this study support surgical intervention as a reasonable option after a repeat Bethesda III classification on FNAB. However, the small sample size warrants confirmation in future studies with a representative sample of patients.