Usefulness of fine-needle aspiration in the diagnosis of thyroid lesions: an institutional experience of 340 patients

Objective: To evaluate the results of fine needle aspiration cytology (FNAC) in the diagnosis, its correlation with histology, to highlight its limitations and diagnostic pitfalls as well as the impact of FNAC on the decreased rate of surgery in clinically suspect thyroid lesions. Study design: FNAC was performed on 340 patients with thyroid enlargement over a period of six years. The cytological results were correlated with clinical features, thyroid function tests and histopathological examination. Results: Among nonneoplastic group, the most frequently encountered lesion was colloid goiter in 231 (67.94%) cases followed by thyroiditis in 68 (20%) cases, five (1.47%) adenomatous goiter and four (1.17%) thyroglossal cysts. Among the neoplastic group, twelve (3.52%) cases were reported as follicular neoplasm, seven (2.05%) cases as Hürthle cell neoplasm and four (1.17%) as malignant tumors. The cytological and histological concordance was determined. A false positive cytologic diagnosis of neoplasms was made in five cases. Presence of Hürthle cell metaplasia, hyperplastic nodules and papillary hyperplasia were responsible for the false positive diagnoses. For the entire series, the false negative rate was 8.57% and the false positive rate was 7.14%. FNA revealed a sensitivity of 62.5%, a specificity of 90.74%, a positive predictive value of 66.66% and a negative predictive value of 89.09%. Conclusion: FNAC is thus an accurate, costeffective, minimally invasive and reliable diagnostic tool for assessment of patients with thyroid lesions and their management.