OBJECTIVE: Fine needle aspiration cytology (FNAC) plays an instrumental role in the workup of a solitary thyroid nodule (STN) by estimating the risk of malignancy (ROM) and assisting in triaging patients to surgery or observation. We conducted a retrospective study to determine the diagnostic efficacy of pre-operative FNAC in the management of STN.

METHODS: From January 2018 to December 2022, 96 patients who underwent hemithyroidectomy at a single center were enrolled. Data of pre-operative FNAC as per Bethesda classification and postoperative outcomes were recorded retrospectively and were correlated. The malignancy conversion rate (the percentage of benign/Indeterminate nodules that turned out to be malignant on the histopathological report) was calculated.

RESULTS: Among the recruited patients, FNAC was performed on 96 patients for STN and they were categorized as Bethesda I-VI (I-5.21%, II-29.17%, III-30.21%, IV-22.92%, V- 1.04%, VI -11.46%). Post-surgery histopathological outcomes were grouped as: benign (n=40/96, 41.67%), neoplastic (n=27/96, 28.13%), and malignant (n=29/96,30.21%). Amongst the Bethesda III AUS (n=29/96), the risk of malignancy conversion was seen as 31.03% (n=9/29), similar to the neoplastic group followed by the benign group (11/29, 37.93%). Overall malignancy conversion rate was found out to be 24.70% (n=21/85) in patients undergoing hemithyroidectomy.

CONCLUSION: The study demonstrated that the percentage of risk of malignancy was significantly higher in Bethesda III and IV than proposed by TBSRTC. There is need for suitable test /molecular marker to increase the diagnostic yield on FNAC