Utility of Liquid-Based Cytology and Conventional Smears in Fine Needle Aspirates of Thyroid Lesions: A Comparative Study

Fine needle aspiration (FNA) is an established technique in evaluation of thyroid nodules. Traditionally, conventional smears (CS) are prepared as an accepted method for cytologic interpretation. However, with the advent and success of liquid-based cytology (LBC) in gynecological and non-gynecological specimens, there has been an increased interest in its application in thyroid FNA as well. Studies evaluating LBC in thyroid aspirates have emerged in recent years and have shown variable results. Patients presenting with complaints of a palpable swelling in the thyroid/midline neck area or with a detectable lesion on ultrasound were subjected to FNA. A split sample technique was used to prepare CS and LBC smears. The cytological diagnosis of CS and LBC was compared with each other and with follow up. The performance of both methods was estimated in terms of sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy. The specificity, positive and negative predictive value, and accuracy of LBC were comparable to CS. The sensitivity of LBC was slightly lower than CS. The diagnostic accuracy of LBC was comparable to CS demonstrating its utility in thyroid FNAs. LBC offers the advantages of lesser screening time, decreased obscuration by blood, decreased artefactual changes, and potential for adjunctive immunocytochemistry/molecular testing. However, due to a higher unsatisfactory rate in benign lesions, LBC may be used as a supplement to CS in thyroid FNAs.