Diagnostic accuracy of fine needle aspiration cytology for thyroid lesions in correlation to histopathology

Abstract

Background: Thyroid enlargement is a common problem and causes various pressure symptoms. Majority of swellings does not require surgery. Fine needle aspiration cytology (FNAC) is considered the gold standard diagnostic test in the evaluation of thyroid swellings. In the present study we correlated the FNAC findings with histopathology so that rate of unnecessary thyroidectomise in benign pathologies could be avoided.
Materials and Methods: The present study is a retrospective and prospective analysis of 298 cases of thyroid swellings which were done over a period of 12 years from August 2001 to July 2012. These cases were underwent FNAC followed by surgery. Correlation of histopathological findings was performed with FNAC. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were calculated for neoplastic and malignant lesions.
Results: Statistical analysis of neoplastic lesions showed sensitivity, specificity, accuracy, false positive rate, false negative rate, positive predictive values, negative predictive value of FNAC 88.6%, 96%, 92.9%, 4%, 11.4%, 94% and 92.3%, respectively whereas statistical analysis of carcinomatous lesions showed sensitivity, specificity, accuracy, false positive rate, false negative rate, positive predictive values, negative predictive value of FNAC 85.4%, 97.3%, 95.7%, 2.7%, 14.6%, 83.3% and 97.8%.
Conclusion: FNAC of thyroid nodules provides the most accurate pre-operative diagnosis than any other diagnostic modality. FNAC is a valuable and minimally invasive procedure and hence considered as a gold standard for pre-operative assessment of patients with thyroid nodules.