Cytomorphological analysis of categories in the Bethesda system and its accuracy in predicting thyroid neoplasms

Abstract

Background: Fine-needle aspiration (FNA) cytology is a keynote modality in diagnosis and screening of thyroid nodules. The management of thyroid nodules largely depends on FNA; thus, it is challenging for the pathologist to distinguish the neoplastic nodule from benign ones and further, categorize the malignant tumors wherever possible. Due to the lack of uniform criteria for specimen adequacy and terminology, “The Bethesda System for Reporting Thyroid Cytopathology (BSRTC)” was designed. Objective: The objective of this study was to review the Bethesda thyroid FNA classification system in evaluation of thyroid nodules. Materials and Methods: This study was conducted over 4½ years. Fine-needle aspiration was done by palpation or ultrasound-guided, using a fine (25 or 27G) needle, and cytological smears were prepared using Giemsa, hematoxylin and eosin, and Papanicolaou stain. These smears were then examined and classified according to the BSRTC. Results: Of the 504 cases analyzed, benign lesions were the most common (78.9%), followed by malignant (4.2%), suspicious for follicular neoplasm/follicular neoplasm (4.2%), atypia/follicular lesion of undetermined significance (3.9%), and suspicious for malignancy (3.6%). Good cytohistological correlation (94.4%) was observed. Only 5.2% smears were nondiagnostic. Limitations: Small sample size for which histopathological follow-up was available. Conclusions: The BSRTC is a systematized 6-tier classification system for thyroid nodule aspirates. It is based on a complete literature analysis and is a unified risk-based reporting system.