What Is the Best Criterion for Repetition of Fine-Needle Aspiration in Thyroid Nodules with Initially Benign Cytology?

Abstract

Background: Traditionally, repetition of fine-needle aspiration (FNA) is indicated for thyroid nodules with initially benign cytology if they exhibit growth. The importance of a repetition has also been demonstrated in the case of suspicious ultrasonography (US) findings. Some authors even consider routine repetition of FNA. The objective of this study was to evaluate the best criterion for FNA repetition in thyroid nodules with initially benign cytology.

Methods: This was a prospective study. Patients with solid nodules that initially showed a benign cytology were selected. The first group was formed by nodules exhibiting suspicious features on initial US (group A, n = 55). The other group consisted of growing nodules without suspicious US features (group B, n = 82). Nongrowing nodules without suspicious features on initial US were divided into two groups: nodules that became suspicious on US (group C.1, n = 18) and those that continued to be unsuspicious (group C.2, n = 398).

Results: In group A, the second FNA resulted in the diagnosis of malignancy in 10 cases (18.2%). In group B, malignancy was confirmed in two cases (2.4%). In group C.1, two nodules were confirmed to be malignant (11.1%). No case of carcinoma was observed in group C.2. Considering the sensitivity and number of FNA biopsies necessary for the detection of each false-negative case of the first FNA, the best criterion to repeat FNA was a suspicious initial or subsequent US. The growth of nodules with unsuspicious US findings was of poorly specificity and required a larger number of FNA biopsies to detect one case of malignancy.

Conclusions: Ultrasonographic features of the nodule are the best parameter for the indication of FNA repetition in nodules with initially benign cytology, while the growth of nodules with unsuspicious US findings has a poor positive predictive value for malignancy.