Role of Fine Needle Aspiration Cytology and Intraoperative Diagnosis in the Diagnosis of Thyroid Nodules

Objective: The utilization of fine needle aspiration cytology-FNAC is an accurate, cost-effective and specific first method in the diagnosis of thyroid nodules. However, cases diagnosed as "inadequate for interpretation" or "suspicious cytology" remain a dilemma. Intraoperative diagnosis (frozen section) is usually performed to avoid unnecessary surgical treatment. The aim of this study was to assess the sensitivity, specificity, and accuracy of FNAC and intraoperative section for the diagnosis of thyroid nodules. Material and Method: The present study included 291 consecutive patients who underwent FNAC, intraoperative section and subsequently surgery. Results: Of 291 FNAC specimens, 213 were benign and 31 were suspicious, 25 were positive for malignancy, and 22 were nondiagnostic. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of FNAC in the diagnosis of malignancy were 43%, 68%, 80%, 72%, and 73%, respectively. No false positive results were noted. Of 291 patients analyzed by intraoperative section, the diagnosis was benign in 186 and positive for malignancy in 67 patients. Thirty-eight patients were diagnosed using permanent sections. Of these 38 patients, 21 had malignant tumors confirmed by the permanent sections. False-positive results were noted in only one case. The sensitivity, specificity, PPV, NPV, and diagnostic accuracy of intraoperative diagnosis were 76%, 82%, 82.8%, 85%, and 84.5%, respectively. Conclusion: FNAC is a sensitive first diagnostic method in selecting patients who require surgery. Routine use of intraoperative section is specific and complementary in determining the extent of surgery in patients with suspicious or malignant cytology.