Clinicopathological Correlation of Core-Needle Biopsy in Thyroid Nodule Assessment: Insights from a Tertiary Care Center.

Background: Fine-needle aspiration cytology (FNAC) is the mainstay for thyroid nodule assessment, boasting excellent specificity and cost-effectiveness. However, its diagnostic limitations often yield nondiagnostic or indeterminate results, especially in complex thyroid cases. Core-needle biopsy (CNB) has emerged as a complementary technique that preserves tissue architecture, enabling improved morphological and molecular analysis. This study compares the diagnostic performance and clinical utility of FNAC and CNB in a tertiary care setting. Materials and Methods: In this retrospective analysis at Sanjay Gandhi Postgraduate Institute of Medical Sciences, 116 patients with thyroid masses underwent both FNAC and CNB between 2014 and 2024. Clinicopathological features, imaging, and cytological/histological data were reviewed. Diagnoses were correlated with final surgical outcomes where available. Results: FNAC adequacy was 96.6%, and CNB adequacy was 99.1%. FNAC's sensitivity, negative predictive value, and diagnostic accuracy were 81.8%, 50%, and 81.5%, respectively, whereas CNB achieved 95.7%, 80%, and 96.2%, respectively. All four nondiagnostic FNAC cases were accurately diagnosed by CNB, with precise subtyping of poorly differentiated, medullary, and anaplastic carcinomas and lymphomas. Conclusion: FNAC is a valuable first-line investigation, but its limitations-especially in indeterminate or high-risk thyroid lesions in tertiary centers-justify early use of CNB. CNB complements FNAC by improving diagnostic yield, subtype accuracy, and suitability for ancillary studies, thus optimizing clinical management and reducing unnecessary surgeries in complex thyroid pathology.