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.

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.

This study was designed to compare diagnostic categories of thyroid fine needle aspiration cytology (FNAC) and incidence of thyroid tumors in the multi-institutional Asian series with a special focus on diagnostic category IV (suspicious for a follicular neoplasm) and follicular thyroid carcinomas (FTCs). Methods: Distribution of FNAC categories, incidence of thyroid tumors in resection specimens and cytologic diagnoses of surgically confirmed follicular adenomas (FAs) and FTCs were collected from 10 institutes from five Asian countries and were compared among countries and between FAs and FTCs. Results: The frequency of category IV diagnoses (3.0%) in preoperative FNAC were significantly lower compared to those in Western countries (10.1%). When comparing diagnostic categories among Asian countries, category IV was more frequent in Japan (4.6%) and India (7.9%) than in Taiwan (1.4%), Korea (1.4%), and China (3.6%). Similarly, incidence of FAs and FTCs in surgical resection specimens was significantly higher in Japan (10.9%) and India (10.1%) than in Taiwan (5.5%), Korea (3.0%), and China (2.5%). FTCs were more commonly diagnosed as category IV in Japan (77.5%) than in Korea (33.3%) and China (35.0%). Nuclear pleomorphism, nuclear crowding, microfollicular pattern, and dyshesive cell pattern were more common in FTCs compared with FAs. Conclusions: Our study highlighted the difference in FNAC diagnostic categories of FTCs among Asian countries, which is likely related to different reporting systems and thyroid cancer incidence. Cytologic features such as nuclear pleomorphism, nuclear crowding, microfollicular pattern, and dyshesive cell pattern were found to be useful in diagnosing FTCs more effectively.

This study was designed to compare diagnostic categories of thyroid fine needle aspiration cytology (FNAC) and incidence of thyroid tumors in the multi-institutional Asian series with a special focus on diagnostic category IV (suspicious for a follicular neoplasm) and follicular thyroid carcinomas (FTCs). Methods: Distribution of FNAC categories, incidence of thyroid tumors in resection specimens and cytologic diagnoses of surgically confirmed follicular adenomas (FAs) and FTCs were collected from 10 institutes from five Asian countries and were compared among countries and between FAs and FTCs. Results: The frequency of category IV diagnoses (3.0%) in preoperative FNAC were significantly lower compared to those in Western countries (10.1%). When comparing diagnostic categories among Asian countries, category IV was more frequent in Japan (4.6%) and India (7.9%) than in Taiwan (1.4%), Korea (1.4%), and China (3.6%). Similarly, incidence of FAs and FTCs in surgical resection specimens was significantly higher in Japan (10.9%) and India (10.1%) than in Taiwan (5.5%), Korea (3.0%), and China (2.5%). FTCs were more commonly diagnosed as category IV in Japan (77.5%) than in Korea (33.3%) and China (35.0%). Nuclear pleomorphism, nuclear crowding, microfollicular pattern, and dyshesive cell pattern were more common in FTCs compared with FAs. Conclusions: Our study highlighted the difference in FNAC diagnostic categories of FTCs among Asian countries, which is likely related to different reporting systems and thyroid cancer incidence. Cytologic features such as nuclear pleomorphism, nuclear crowding, microfollicular pattern, and dyshesive cell pattern were found to be useful in diagnosing FTCs more effectively.

This study was designed to compare diagnostic categories of thyroid fine needle aspiration cytology (FNAC) and incidence of thyroid tumors in the multi-institutional Asian series with a special focus on diagnostic category IV (suspicious for a follicular neoplasm) and follicular thyroid carcinomas (FTCs). Methods: Distribution of FNAC categories, incidence of thyroid tumors in resection specimens and cytologic diagnoses of surgically confirmed follicular adenomas (FAs) and FTCs were collected from 10 institutes from five Asian countries and were compared among countries and between FAs and FTCs. Results: The frequency of category IV diagnoses (3.0%) in preoperative FNAC were significantly lower compared to those in Western countries (10.1%). When comparing diagnostic categories among Asian countries, category IV was more frequent in Japan (4.6%) and India (7.9%) than in Taiwan (1.4%), Korea (1.4%), and China (3.6%). Similarly, incidence of FAs and FTCs in surgical resection specimens was significantly higher in Japan (10.9%) and India (10.1%) than in Taiwan (5.5%), Korea (3.0%), and China (2.5%). FTCs were more commonly diagnosed as category IV in Japan (77.5%) than in Korea (33.3%) and China (35.0%). Nuclear pleomorphism, nuclear crowding, microfollicular pattern, and dyshesive cell pattern were more common in FTCs compared with FAs. Conclusions: Our study highlighted the difference in FNAC diagnostic categories of FTCs among Asian countries, which is likely related to different reporting systems and thyroid cancer incidence. Cytologic features such as nuclear pleomorphism, nuclear crowding, microfollicular pattern, and dyshesive cell pattern were found to be useful in diagnosing FTCs more effectively.