A Retrospective Analysis of the Preoperative Cytological Diagnosis of Histologically Proven Papillary Thyroid Carcinoma; Single Center Clinical Audit in Sri Lanka
Madhara RajapaksePURPOSE
Papillary thyroid carcinoma (PTC) is the third commonest cancer, among the both sexes in Sri Lanka. Most cases are asymptomatic and detected ultrasonically. Fine-needle aspiration cytology (FNAC) is the primary screening test for the clinically and ultrasonically suspicious thyroid nodules. Bethesda System for Reporting Thyroid Cytopathology is the widely accepted standardized reporting system for the thyroid cytology, where six Bethesda categories (BC) are being used, including BC1 to BC6. Introduction of Bethesda System has improved diagnostic consistency and communication between pathologists and clinicians. The main purposes of this study are to determine cytological-histological concordance rates of PTC and to improve the diagnostic accuracy and reporting standards of thyroid FNAC in local set-up.
METHODS
A retrospective review was done in 51 cases of conventional type PTC cases, received during 2025 to the department of histopathology, National Hospital, Galle, Sri Lanka. Data were extracted from the request forms and virtual archives.
RESULTS
Majority of the cases (n = 20, 39.2%) were preoperatively categorized in to either BC5 or BC 6 category. BC 4 category was offered for 5 cases (9.8%). 7 cases (13.7%) were offered BC3 category. 18 (35.3%) cases were given BC2 category. Only 1 (2%) case was offered BC1 category. Out of all the considered 51 conventional PTC cases, 21 cases had less than 10 mm in maximum diameter, which were previously categorized as papillary microcarcinoma (TNM stage pT1a). Most of the BC2 nodules (n = 18) were found to be at stage pT1a.
CONCLUSION
FNAC is a reliable and effective diagnostic modality for papillary thyroid carcinoma, showing an overall high concordance level with the final histopathology. Specific cytological features such as papillaroid clusters or papillary tips, enlarged, overlapping, round to oval nuclei with nuclear grooves and nuclear pseudo inclusions points to the correct diagnosis. False-negative results may be due to errors in sampling techniques, especially in small or cystic lesions, interpretation challenges in cases such as follicular-patterned variants of PTC. Clinical audits are essential in assessing the diagnostic accuracy, identify pitfalls, and improving the overall standard of the reports within individual institutions, particularly in resource-limited settings.