A Comparative Study of Fine-Needle Aspiration and Nonaspiration Cytology Diagnosis in Thyroid Lesions

Aspiration cytology is one of the first-line diagnostic tests in thyroid malignancies. Fine-needle aspiration cytology (FNAC) in thyroid lesions causes hemorrhagic smear and cell trauma, often leading to the repetition of smear and delay in diagnosis. This study was conducted to identify the diagnostically superior technique with regard to thyroid swelling and to assess the quality of smears obtained from FNAC and fine-needle nonaspiration cytology (FNNAC).

This was a prospective diagnostic study carried out for 2 years in a tertiary care center from South India. All patients with complaints of thyroid swellings, after examination, underwent FNNAC, followed by FNAC of the lesion. They underwent thyroidectomy when indicated. The final postoperative biopsy reports were compared with the preoperative reports of these two techniques (FNNAC and FNAC). The quality of smears was compared using Mair's score.

The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy in diagnosing malignancy were 93.4%, 100%, 100%, 98.78%, and 98.96% for FNNAC and 94.12%, 100%, 100%, 98.82%, and 99% for FNAC, respectively, which were comparable. Regarding the quality of smears, FNNAC had more smears with less blood in the background. FNAC had more smears with adequate cellularity. The difference in overall Mair's score between the two techniques was not significant (P = 0.28).

No difference was found in the accuracy of FNAC and FNNAC in diagnosing thyroid lesions. Furthermore, the smear quality of both techniques was comparable. Hence, either can be used based on the operator's preference and experience.