Reliability of fine-needle aspiration and ultrasound-based characteristics of thyroid nodules for diagnosing malignancy in Iranian patients

Abstract

Background: Sonography and fine-needle aspiration biopsy (FNA-B) have been approved as method of choice in diagnosis of malignant thyroid nodules. Unnecessary FNA-B not only is invasive and costly but also results in second biopsy or unnecessary surgery. So we aimed to determine the specificity and sensitivity of sonography and FNA-B, without sonography guidance, in diagnosis of malignant and benign thyroid nodules.

Methods: Patients with thyroid nodule referred to Baqiyatallah Hospital in 2014-2015 and candidates for surgical nodule resection were selected using simple random sampling method. Patients were evaluated by sonography and FNA. Sonographic characteristics of nodule were described. All patients underwent surgical resection and gross samples were sent for pathological evaluation, the gold standard for measuring the specificity and sensitivity of sonographic findings and FNA in diagnosis of malignant nodules.

Results: Ninety patients with the mean age of 45.95 ± 12.3 years were evaluated (17 male and 73 female). Comparing the patients with correct and incorrect sonography-based diagnosis showed significant differences in nodule's width, area, calcification, border, and cervical lymphadenopathy (P < 0.05). Comparing the patients with correct and incorrect FNA-based diagnosis showed significant differences in patients' age and tall-shape nodule (P < 0.05). The diagnosis of sonographist had 56.25% sensitivity and 95.9% specificity, and the FNA-based diagnosis had 81.25% sensitivity and 93.7% specificity.

Conclusion: Among sonography findings, width and area of nodule, calcification, and nodule border have significant effect on malignancy diagnosis. Also FNA is necessary in nodules with calcification, border irregularity, and less width and area, especially in younger patients.

Keywords: fine-needle aspiration; sensitivity; specificity; thyroid cancer; thyroid nodule; ultrasonography; ultrasound characteristics.