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Thyroid Fine-Needle Aspiration Cytology Practice in Korea
Yoon Jin Cha1, Ju Yeon Pyo1, SoonWon Hong1
1Department of Pathology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
Insights
Thyroid fine-needle aspiration cytology (FNAC) in Korea has advanced significantly since 1977, with widespread adoption of The Bethesda System for Reporting Thyroid Cytopathology. Current practices integrate molecular testing and liquid-based cytology for improved thyroid nodule diagnosis.
Area of Science:
- Endocrinology
- Pathology
- Cytopathology
Background:
- Thyroid fine-needle aspiration cytology (FNAC) is a crucial diagnostic tool for thyroid nodules.
- Standardization of diagnostic guidelines and reporting systems is essential for accurate patient management.
Purpose of the Study:
- To review the current status and evolution of thyroid FNAC practices in Korea.
- To assess the adoption and impact of The Bethesda System for Reporting Thyroid Cytopathology in Korean institutions.
Main Methods:
- Review of historical data and current practices in Korean thyroid FNAC.
- Analysis of diagnostic rates and malignancy rates across Bethesda categories.
- Evaluation of the utilization of liquid-based cytology, immunocytochemistry, molecular testing, and core biopsies.
Main Results:
- The Bethesda System is used by 94% of institutions, with specific average diagnosis and malignancy rates per category.
- Liquid-based cytology is utilized by 68% of institutions.
- Core biopsies are performed infrequently, with limited use even in institutions that offer them.
Conclusions:
- Thyroid FNAC in Korea has largely adopted standardized reporting systems like The Bethesda System.
- Integration of advanced techniques such as molecular testing and liquid-based cytology is increasing.
- Further consensus on indeterminate diagnostic categories and optimal use of ancillary techniques is needed.
Abstract:
We reviewed the current status of thyroid fine-needle aspiration cytology (FNAC) in Korea. Thyroid aspiration biopsy was first introduced in Korea in 1977. Currently, radiologists aspirate the thyroid nodule under the guidance of ultrasonography, and cytologic interpretation is only legally approved when a cytopathologist makes the diagnosis. In 2008, eight thyroid-related societies came together to form the Korean Thyroid Association. The Korean Society for Cytopathology and the endocrine pathology study group of the Korean Society for Pathologists have been updating the cytologic diagnostic guidelines. The Bethesda System for Reporting Thyroid Cytopathology was first introduced in 2009, and has been used by up to 94% of institutions by 2016. The average diagnosis rates are as follows for each category: I (12.4%), II (57.9%), III (10.4%), IV (2.9%), V (3.7%), and VI (12.7%). The malignancy rates in surgical cases are as follows for each category: I (28.7%), II (27.8%), III (50.6%), IV (52.3%), V (90.7%), and VI (100.0%). Liquid-based cytology has been used since 2010, and it was utilized by 68% of institutions in 2016. The categorization of thyroid lesions into "atypia of undetermined significance" or "follicular lesion of undetermined significance" is necessary to draw consensus in our society. Immunocytochemistry for galectin-3 and BRAF is used. Additionally, a molecular test for BRAF in thyroid FNACs is actively used. Core biopsies were performed in only 44% of institutions. Even the institutions that perform core biopsies only perform them for less than 3% of all FNACs. However, only 5% of institutions performed core biopsies up to three times more than FNAC.
