Core Needle Biopsy for the Diagnosis of Thyroid Nodules: Pathologic Aspects

Fine-needle aspiration (FNA) cytology is a cost-effective and safe diagnostic tool used for the preoperative screening of thyroid nodules. However, the limitations of cytology include relatively high rates of nondiagnostic and indeterminate results and difficulty applying ancillary testing. Core needle biopsy (CNB) is an alternative to FNA cytology to evaluate thyroid nodules with initially nondiagnostic or indeterminate results by FNA. Recent studies have reported the usefulness of CNB as a first-line diagnostic tool. Thyroid CNB provides a tissue sample that retains histologic architecture and cytologic findings. With sufficient tissue for histologic examination and additional ancillary testing, an accurate diagnosis is possible without the need for a repeat biopsy or subsequent surgery. Although concern exists about the potential complications of CNB, recent studies have revealed that ultrasound-guided CNB is safe. Recent advances in CNB devices allow for safer procedures and accurate diagnoses. The Korean Endocrine Pathologists’ consensus on the pathology report of thyroid CNB can efficiently communicate the CNB diagnosis to the referring clinicians. The reporting system of thyroid CNB adopts six diagnostic categories similar to the Bethesda System for reporting thyroid FNA. This review covers the clinical application and pathology reporting system of thyroid CNB and approaches to challenging cases.