The Impact of Thyroid Nodule Size and Fine-Needle Aspiration Biopsy Result on the Risk of Malignancy in the Patients Who Underwent Thyroidectomy

Abstract

Background and Objectives The frequency of ultrasonography and cytological examinations for thyroid nodules has increased. But the efficacy of fine needle aspiration biopsy varies according to the size of the nodules. The study aimed to identify the effect of thyroid nodule size on malignancy. Subjects and Method The medical records of patients who underwent total or hemithryoidectomy in a single tertiary hospital were retrospectively analyzed. A total of 204 nodules were obtained from 193 patients who underwent fine needle aspiration biopsy before thyroid surgery. After each nodule was classified by size, the results of the fine needle aspiration test and risk of the final diagnosis were evaluated using logistic regression analysis. Results The average size of 204 Bethesda class 2 (benign) nodules was 2.99 cm, which was larger than those of other classes (p;＜0.05). In the final histopathologic diagnosis, there was a difference in size between benign (2.41 cm) and malignant nodules (1.23 cm) (p;＜0.05). In addition, a logistic regression analysis showed that the nodules below 2.0 cm in size showed an odd ratio of 7.81, compared to the nodules larger than 2.0 cm (p;＜0.05). Conclusion According to the results of this study, malignancy was higher when the thyroid nodule was less than 2 cm. Therefore, a careful observation is needed for nodules less than 2 cm for which fine needle aspiration biopsy would be recommended. Conversely, it is necessary to reconsider the diagnostic surgery for nodules larger than 2 cm. Key words: Biopsy ㆍ Fine-needle ㆍ Thyroid gland ㆍ Thyroid neoplasms ㆍ Thyroid nodule