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

Abstract

Thyroid core needle biopsy (CNB) has been used as an alternative to fine needle aspiration (FNA) cytology since the 1990s [1, 2]. The use of CNB is increasing as a second-line diagnostic tool for lesions in which FNA was nondiagnostic due to low cellularity or in which the FNA result was inconclusive [1, 3, 4]. It has been shown that CNB can reduce the rate nondiagnostic and indeterminate results more efficiently than FNA cytology [1, 4, 5, 6]. Although ultrasound-guided FNA cytology has been used as a gold-standard method for the preoperative screening of thyroid nodules, the inherent limitations of cytology include (1) nondiagnostic rate of 2–41% [7], (2) indeterminate results (atypia of undetermined significance [AUS]/follicular lesion of undetermined significance [FLUS], follicular neoplasm, and suspicious for malignancy) ranging from10% to 75% [8], and (3) difficulty applying ancillary testing on conventional cytology. Thyroid CNB provides a tissue sample that retains histologic architecture and cytologic findings. Furthermore, 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 in diagnosing lesions of patients with lymphoma, diseases of nonthyroidal origin, and other rare thyroid diseases.