Understanding Neoplasm of Uncertain or Unknown Behavior of the Thyroid in Korean Clinical Practice

ABSTRACT

Thyroid tumors include a heterogeneous group of entities with variable clinical behavior and histology, mostly classified as benign or malignant. Neoplasm of uncertain or unknown behavior in thyroid gland was newly adopted by the 2017 edition of World Health Organization (WHO) classification of endocrine organs. The borderline thyroid tumors include a hyalinizing trabecular tumor and three encapsulated follicular-patterned thyroid tumors (follicular tumor of uncertain malignant potential, well-differentiated tumor of uncertain malignant potential, and non-invasive follicular thyroid neoplasm with papillary-like nuclear features). This review summarizes the changes in the 2017 WHO classification of thyroid tumors, highlights their implications for clinical practice in Korea, and briefly discusses National Health Insurance system, cancer insurance policies, and their associated benefits in Korea.