Predictive value of a single highest suspicious ultrasound feature in subcentimeter thyroid nodules: a retrospective observational cohort study

Abstract Purpose Proper management of subcentimeter thyroid nodules remains challenging for both clinicians and patients. Conducting extensive sonographic research using a safe and inexpensive tool for identifying thyroid nodules is necessary. This study aimed to identify whether having a highest ultrasound (US) risk characteristic suggests that US-guided fine-needle aspiration (FNA) biopsy in subcentimeter nodules is more appropriate for the identification of malignancy than active surveillance (AS) or surgery. Methods The data of patients with highly suspicious subcentimeter thyroid nodules with US characteristics who underwent surgery were retrospectively examined. Results Among a total of 556 subcentimeter nodules, 223 (40.1%) were benign and 333 (59.9%) were malignant, with a mean maximal nodule size of 8.1 mm. The US features that were significantly associated with malignancy were age below 45 years, irregular margin, presence of microcalcification, and a taller-than-wide shape (P < 0.001). Multivariate analysis also identified a taller-than-wide shape (OR = 8.988, P = 0.0015) as an independent factor associated with malignancy in subcentimeter thyroid nodules. The diagnostic performance of the preoperative FNA was classified as a malignancy, with a sensitivity of 98.4%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 76.9%. Conclusions This study is one of the few reports based on actual data of highest suspicious US features in thyroid subcentimeter nodules. A taller-than-wide shape is the US feature most significantly associated with malignancy. FNA is a simple, accurate, and reliable preoperative method for diagnosing malignant subcentimeter thyroid nodules with highly suspicious US characteristics. AS was less appropriate than FNA for subcentimeter nodules with a taller-than-wide shape, especially in patients ≤ 45 years.