Diagnostic Accuracy of Frozen Section in Comparison With Fine Needle Aspiration Cytology in Thyroid Lesions – A Prospective Study

Background and Objectives: Thyroid gland because of its superficial location is amenable to direct physical examination. Clinical assessment of thyroid lesions by means of physical examination, thyroid scans and ultrasonography is not completely reliable. Fine needle aspiration cytology (FNAC) is the most cost-effective, safe and an initial diagnostic test in the pre-operative evaluation of thyroid lesions. Many surgeons use intraoperative frozen section biopsies to confirm the diagnosis of FNAC and guide the extent of thyroidectomy. Therefore, the objective of the present study was to assess the diagnostic accuracy of frozen section in comparison with fine needle aspiration cytology and histopathology in thyroid lesions. Materials & Methods: Fine needle aspiration cytology and frozen section (FS) were evaluated in 59 patients. FNAC was classified as benign, malignant and suspicious, and FS was classified as benign, deferred and malignant. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy were calculated for both FS and FNAC. Results: Out of 59 patients, 3 were positive for malignancy, 51 were benign, and five were suspicious on FNAC. Over all accuracy of fine needle aspiration cytology was 93%. Five were positive for malignancy, 50 were benign and 4 were “deferred” in frozen section. Over all accuracy of frozen section was 96%. Discussion: Fine needle aspiration cytology can be used primarily to select patient for surgery and frozen section can be employed to plan the extent of surgery. Frozen section had a good accuracy, sensitivity and negative predictive value compared to fine needle aspiration cytology.