Delayed Cancer Diagnosis in Thyroid Nodules Initially Treated as Benign With Radiofrequency Ablation - Ultrasound Characteristics and Predictors for Cancer

Sep 24, 2026

Regrowth after radiofrequency ablation (RFA) of symptomatic large thyroid nodules initially classified as benign can later reflect occult malignancy. This retrospective study assessed ultrasound (US) features of nodules that were later diagnosed as cancer, identified predictors of malignancy masquerading as benign, and evaluated strategies to avoid RFA in such cases. Records from 134 patients with 148 nodules treated between 2008 and 2016 were analyzed, correlating pre-RFA imaging with follow-up changes and final surgical pathology.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages9

Reading Time23 min

AccessFree to download

Objective

Materials and Methods

Study Patients

Results

Conclusion

Keywords

Original Article | Thyroid eISSN 2005-8330 [https://doi.org/10.3348/kjr.2023.0386](https://doi.org/10.3348/kjr.2023.0386)[ ](https://doi.org/10.3348/kjr.2023.0386)[Korean J Radiol 2023](Korean J Radiol 2023);[24](24)([9](9))[:903-911](:903-911) Delayed Cancer Diagnosis in Thyroid Nodules Initially Treated as Benign With Radiofrequency Ablation: Ultrasound Characteristics and Predictors for Cancer Myoung Kyoung Kim, Jung Hee Shin, Soo Yeon Hahn, Haejung Kim Department of Radiology and Center for Imaging Science, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea Objective: Regrowth after radiofrequency ablation (RFA) of symptomatic large thyroid nodules, initially treated as benign, sometimes turns out to be malignancies. This study aimed to assess the ultrasound (US) characteristics of thyroid nodules initially treated as benign with RFA and later diagnosed as cancers, predictive factors for cancers masquerading as benign, and methods to avoid RFA in these cancers. Materials and Methods: We reviewed the medical records of 134 consecutive patients with 148 nodules who underwent RFA between February 2008 and November 2016 for the debulking of symptomatic thyroid nodules diagnosed as benign using US-guided biopsy. We investigated the pre-RFA characteristics of the thyroid nodules, changes at follow-up after RFA, and the final surgical pathology. Results: Nodule regrowth after RFA was observed in 36 (24.3%) of the 148 benign nodules. Twenty-two of the 36 nodules were surgically removed, and malignancies were confirmed in seven (19.4% of 36) . Of the 22 nodules removed surgically, pre-RFA median volume (range) was significantly larger for malignant nodules than for benign nodules: 22.4 (13.9–84.5) vs. 13.4 (7.3–16.8) mL (P = 0.04) . There was no significant difference in the regrowth interval between benign and malignant nodules (P = 0.49) . The median volume reduction rate (range) at 12 months was significantly lower for malignant nodules than for benign nodules (51.4%[0–57.8] vs. 83.8%[47.9–89.6]) (P = 0.01) . The pre-RFA benignity of all seven malignant nodules was confirmed using two US-guided fine-needle aspirations (FNAs), except for one nodule, which was confirmed using US-guided core-needle biopsy (CNB) . Regrown malignant nodules were diagnosed as suspicious follicular neoplasms by CNB. Histological examination of the malignant nodules revealed follicular thyroid carcinomas, except for one follicular variant, a papillary thyroid carcinoma. Conclusion: Symptomatic large benign thyroid nodules showing regrowth or suboptimal reduction after RFA may have malignant potential. The confirmation of these nodules is better with CNB than with FNA. Keywords: Thyroid nodule; Radiofrequency ablation; Ultrasonography; Follicular thyroid carcinoma INTRODUCTION Radiofrequency ablation (RFA) is a minimally invasive technique for the treatment of various tumors that has been demonstrated to be effective in patients with symptomatic benign thyroid nodules [1-4] and recurrent thyroid cancers [5-7] . Since 2001, many studies, including randomized controlled trials and meta-analyses, have reported the effectiveness and safety of this approach, resulting in its widespread application in patients with benign thyroid nodules [8-12] . Prior to RFA, thyroid nodules should be confirmed as benign based on at least two ultrasound (US)-guided fineneedle aspirations (FNAs) or core-needle biopsy (CNB) Received: April 26, 2023 Revised: June 26, 2023 Accepted: July 5, 2023 Corresponding author: Jung Hee Shin, MD, PhD, Department of Radiology and Center for Imaging Science, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Republic of Korea • E-mail: [jhshin11@skku.edu](jhshin11@skku.edu) This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercia

FAQs

What was the study’s main objective regarding RFA-treated thyroid nodules?

To evaluate ultrasound characteristics of nodules initially treated as benign with RFA but later diagnosed as cancers, and to identify predictive factors and methods to avoid RFA in these malignancies.

How were patients selected for the analysis?

The study reviewed 134 consecutive patients (148 nodules) who underwent US-guided RFA between February 2008 and November 2016 for symptomatic benign nodules, excluding those without follow-up US findings after RFA.

What ultrasound-related approach improved cancer confirmation after regrowth?

Confirmation was better with core-needle biopsy (CNB) than with fine-needle aspiration (FNA) for regrown malignant nodules.

Sep 24, 2026

Uploaded by Chumphorn