In Taiwan, thyroid cancer is the most common endocrine gland malignancy and the incidence of thyroid cancer has increased four-fold in the past two decades. Fine-needle aspiration is an accurate and cost-effective method of evaluating thyroid nodules and has been the gold-standard diagnostic tool for thyroid tumors in Taiwan since the 1980s. This article reviews the history, current practice, reporting systems, training, and quality assurance for thyroid fine-needle aspiration cytology in Taiwan.
Biopsy, Fine-Needle* ; Endocrine Glands ; Incidence ; Methods ; Taiwan* ; Thyroid Gland* ; Thyroid Neoplasms ; Thyroid Nodule

In Taiwan, thyroid fine-needle aspiration cytology is easily accessible and reliable for evaluating thyroid nodules. The sonographic pattern plays a major role and is the deciding factor for aspiration. We conducted a nationwide survey in 2017 and it revealed that 31% of laboratories had adopted The Bethesda System for Reporting Thyroid Cytopathology. There was a relatively high unsatisfactory rate (24.04%) and low rates of indeterminate diagnoses, including atypia of undetermined significance/follicular lesions of undetermined significance: 4.87%, and follicular neoplasm/suspicious for a follicular neoplasm: 0.35%. Moreover, the risks of malignancy in benign, atypia of undetermined significance, and suspicious for a follicular neoplasm were relatively high. These may reflect strict diagnostic criteria for indeterminate categories and better patient selection for surgery. Improvements in specimen sampling and continuing education programs are crucial. Newly-developed thyroid cytology technologies, such as immunocytochemistry, molecular testing, and computerized cytomorphometry, may further facilitate cytology diagnoses.

Background: Assessing nuclear features is diagnostically challenging in the aspect of thyroid pathology. The aim of this study was to determine whether pathologists could distinguish BRAF-like and RAS-like nuclear features morphologically and identify morphological features to differentiate thyroid tumors with RAS-like mutations from encapsulated papillary thyroid carcinoma (PTC) with predominant follicular growth and BRAFV600E mutation. Methods: Representative whole slide images of 16 encapsulated thyroid tumors with predominant follicular growth were reviewed by 12 thyroid pathologists using a web browser-based image viewer. Total nuclear score was calculated from semi-quantitatively scored eight nuclear features. The molecular profile of RAS and BRAF genes was determined by Sanger sequencing. Results: Total nuclear score ranging 0 to 24 could differentiate BRAF-like tumors from RAS-like tumors with a cut-off value of score 14. The interobserver agreement was the highest for the assessment of nuclear pseudoinclusions (NPIs) but the lowest for nuclear elongation and sickle-shaped nuclei. NPIs were found in tumors with BRAFV600E mutation, but not in tumors with RAS-like mutations. Total nuclear scores were significantly higher for tumors with BRAFV600E than for those with RAS-like mutations (P<0.001). Conclusion Our results suggest that NPIs and high nuclear scores have diagnostic utility as rule-in markers for differentiating PTC with BRAFV600E mutation from benign or borderline follicular tumors with RAS-like mutations. Relaxation of rigid criteria for nuclear features resulted in an overdiagnosis of PTC. Immunostaining or molecular testing for BRAFV600E mutation is a useful adjunct for cases with high nuclear scores to identify true PTC.

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.