Cyto-Histomorphological Analysis of Thyroid Lesions and Risk Assessment of Malignancy/Neoplasia: Insights From a North Indian Tertiary Oncology Center

Background Thyroid nodules, whether benign or malignant, are commonly identified as palpable or incidental findings. Accurate diagnosis is critical, with fine-needle aspiration cytology (FNAC) playing a crucial role in distinguishing between benign and malignant lesions. The Bethesda System for Reporting Thyroid Cytopathology (BSRTC) standardizes FNAC reporting and estimates the risk of malignancy (ROM), aiding treatment decisions. This study aims to determine the risk of malignancy for each category of the Bethesda System and to evaluate the sensitivity and specificity of FNAC in diagnosing thyroid swellings. Methodology Clinicopathological data of thyroid FNAC and corresponding thyroid resection cases, collected over four years at the Department of Oncopathology, Mahamana Pandit Madan Mohan Malviya Cancer Centre and Homi Bhabha National Institute, Varanasi, were analyzed. Results A total of 559 patients (372 females, 187 males) with a median age of 49 years were evaluated. Among the BSRTC categories, Category VI (32.4%) and Category II (29.2%) were the most common. ROM for each category was as follows: 50%, 25%, 30%, 85.71%, 97%, and 100%, respectively. FNAC demonstrated a sensitivity of 98%, a specificity of 64%, a positive predictive value of 96%, and a negative predictive value of 75%. Concordance between cytopathological and histopathological findings for malignant cases was 69.8%. Papillary thyroid carcinoma was the most common malignancy. Conclusions The ROM for categories I, II, and III was significant, highlighting the importance of the six-tier reporting system. The BSRTC system standardizes reporting and clinical management. Our data, primarily from an oncology center, may vary based on the expertise of the pathologist, laboratory setup, and patient demographics.