Undercover active surveillance of small highly suspicious thyroid nodules without fine needle aspiration

Purpose Active surveillance (AS) is an alternative treatment approach for small, low-risk papillary thyroid microcarcinoma (PTMC). This study aimed to assess the clinical outcomes of small, highly suspicious nodules lacking initial cytological confirmation.Methods This study included 112 patients with highly suspicious nodules measuring <= 10 mm who underwent serial ultrasound at Asan Medical Center, Korea, between 2010 and 2023.Results The median participant age was 51.9 years, and 74.1% were female. The median maximal tumor diameter and tumor volume (TV) were 4.5 (interquartile range [IQR] 3.7-5.2, range 2.2-9.3) mm and 25.2 (IQR 13.1-49.2) mm(3), respectively. During a median follow-up period of 4.8 years, four (3.6%) patients showed a >= 3 mm increase in maximal diameter, and two (1.8%) developed new lymph node (LN) metastasis. Disease progression was associated with a TV doubling time (TVDT) of < 5 years and a >= 75% increase in TV (p = 0.017 and p < 0.005, respectively). Furthermore, 34.8% of patients underwent fine needle aspiration (FNA), primarily at their own request, yielding 46.2%, 5.1%, 41.0%, and 12.8 % malignant, benign, indeterminate, and non-diagnostic results, respectively. Of 18 patients with PTMC, 8 (44.4%) underwent surgery and 10 continued AS, with no LN metastasis during AS and no postoperative recurrence.Conclusion Small, highly suspicious nodules had a low disease progression rate during AS without FNA. Disease progression was associated with a TVDT of < 5 years and a >= 75% increase in TV. FNA can be performed more conservatively than it currently is in patients with highly suspicious nodules measuring <= 10 mm.