Radiofrequency ablation for difficult thyroid nodule resulting complete resolution after following 6 months: a case report

Introduction

Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer and carries the best overall prognosis (1), which usually managed with total thyroidectomy as recommended by the current guidelines. Following subtotal thyroidectomy, patients may experience residual or recurrent disease, especially in cases of advanced or multifocal tumors which are considered a challenge in terms of management (2). The residual disease can be detected through elevated thyroglobulin levels, high thyroid-stimulating hormone (TSH), and radiologic findings, which required additional intervention to prevent further disease progression (3). The options for management include re-operative surgery, radio-iodine therapy, and, more recently, radiofrequency ablation (RFA). RFA is a minimally invasive alternative for managing small residual or recurrent tumors with minimal morbidity compared to conventional re-operation as neck dissection will be difficult for surgeons due to distortion in the normal tissue plane, fibrosis, adhesion, and complications such as nerve injury, and hypoparathyroidism (4). This case illustrates the management of thyroid nodules following subtotal thyroidectomy for PTC, and the role and potential benefits of RFA as a minimally invasive treatment option. We present this case report in accordance with the CARE reporting checklist (available at https://jovs.amegroups.com/article/view/10.21037/jovs-24-32/rc).

Case presentation

A 43-year-old female was diagnosed with PTC in October 2022 at a peripheral hospital. Ultrasound imaging revealed that the left thyroid lobe measured 12 cm × 6.7 cm × 6.1 cm, extending beyond the sternum and indenting the brachiocephalic vein without evidence of invasion. Also, it was causing deviation of the trachea to the contralateral side. The left lobe was occupied by multiple coalescences predominantly solid nodules with occasional foci of macro calcification consistent with thyroid imaging reporting and data system (TIRADS) category 4 for fine needle aspiration (FNA). The right thyroid lobe and isthmus appeared within the normal size, with multiple small isoechoic nodules classified as TIRADS category 3.

The patient underwent subtotal thyroidectomy at a peripheral hospital, with the pathology report confirming a diagnosis of papillary microcarcinoma, a follicular variant, non-encapsulated, infiltrative, reaching the fat but without involvement of skeletal muscle or vessels. C-3, 4 & 5, PT1a, there was evidence of extrathyroidal extension. Postoperatively, the patient was started on radioactive iodine (RAI) therapy without receiving the appropriate dose and preparation. Six months after subtotal thyroidectomy, the patient presented to our surgical clinic with elevated TSH and thyroglobulin level was around 9.8. She reported no compressive symptoms, and there were no signs of hypothyroidism or hyperthyroidism. The patient was on levothyroxine 175 mcg twice weekly, 125 mcg twice weekly then increased to 175 mcg daily. Ultrasound imaging revealed residual thyroid tissue in the left thyroid bed, measuring 1 cm × 1 cm × 3.7 cm, with an ill-defined, hypoechoic solid nodule measuring 0.9 cm. This nodule was classified as TIRADS category 5 (highly suspicious). FNA of the nodule showed atypia of undetermined significance, with a Bethesda category 3 result. No suspicious cervical lymphadenopathy was noted. Given the indeterminate nature of the FNA result, molecular testing was considered, however, it was not performed due to its unavailability in our center.

Follow-up ultrasound demonstrated stable residual tissue on the left side 4 cm × 1 cm, with a solid, ill-defined, hypoechoic lesion measuring 0.8 cm × 0.8 cm, and punctate echogenic calcifications, consistent with TIRADS category 5. The second FNA of the same lesion revealed a colloid follicular nodule with mild atypia of undetermined significance in a few follicular cells. No cervical lymphadenopathy was noted. Additionally, a small residual thyroid tissue was identified on the right side, measuring approximately 0.6 cm × 0.9 cm, without any distinct nodules. The patient subsequently underwent a completion thyroidectomy to remove the left thyroid remnant. The operation was difficult due to the fibrosis, but the left thyroid remnant was identified and excised, with the lateral surface of the thyroid shaved off inferiorly, up to the left subclavian vessels. The surgical pathology report revealed thymic tissue and adjacent small lymph nodes, no malignant cells. Postoperatively, ultrasound showed a reduction in the size of the right-side residual tissue, now measuring approximately 0.13 cm × 0.4 cm, without distinct nodules. The left side residual tissue remained stable at 3.5 cm × 0.8 cm, with a hypoechoic ill-defined lesion measuring 0.8 cm × 0.7 cm, and no suspicious cervical lymphadenopathy. The third FNA from the left nodule revealed a benign follicular nodule. Six months following the completion of the thyroidectomy, the patient underwent RFA of the residual thyroid nodule. The procedure was performed in an outpatient setting under ultrasound guidance. At the time of the intervention, there were no immediate complications, and the patient tolerated the procedure well. The procedure is explained in Video 1. We followed up with the patient 6 months after the ablation procedure, during which no hoarseness was observed, and there was complete resolution of the nodule. Thyroglobulin level dropped to 2.26 and thyroglobulin antibody was 3.7.

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for the publication of this case report and the video. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

PTC is the most common form of thyroid malignancy, which has a favorable prognosis, especially in low-risk patients. However, management of residual or recurrent disease following subtotal thyroidectomy presents a clinical challenge. In the case presented, despite initial subtotal thyroidectomy, the patient received suboptimal treatment and experienced persistent thyroid tissue with a solid, ill-defined hypoechoic nodule, with elevated thyroglobulin, FNA was taken three times. However, there was a concern about residual disease with lack of molecular testing availability. This highlights the importance of careful surveillance and the consideration of alternative treatment options, such as RFA, for managing small, residual thyroid nodules. Subtotal thyroidectomy remains a common approach for large, locally advanced, or multinodular PTC to minimize the risk of postoperative hypothyroidism and avoid unnecessary total thyroidectomy, but the current guidelines recommend total thyroidectomy. However, the risk of residual thyroid tissue and recurrent disease remains, particularly in the setting of extrathyroidal extension, as was noted in this patient’s initial pathology report (5). While RAI therapy is often employed as a subsequent treatment to ablate any remaining thyroid tissue, it is not without its limitations. The patient in this case underwent RAI therapy with large remnant, a critical factor known to affect the efficacy of the treatment (6). Suboptimal RAI treatment can results in incomplete ablation, which may require further intervention, as seen in this patient. RFA is a minimally invasive effective therapy for managing residual or recurrent thyroid cancer, especially in cases of small, localized lesions. It uses heat generated by high-frequency electrical currents which induce necrosis of the target tissue, with a lower rate of morbidity, and shorter recovery times (7). Furthermore, RFA is effective in patients with such nodule in patients who are not candidates for further surgical resection or RAI, particularly in those with small, and stable nodules. In this case, after multidisciplinary discussion as the patient came to us as suboptimal treatment with elevated thyroglobulin, the decision was for undergoing RFA 6 months following completion of thyroidectomy, it was successful with complete resolution of the nodule, and no signs of new or progressive disease. The follow up after RFA was based on ultrasound, thyroglobulin and our clinical judgment since there was no clear guideline. Despite its advantages in terms of local control and patient outcomes, the use of RFA in thyroid cancer management is still evolving. Further studies need to establish its long-term efficacy and refine patient selection criteria.

Conclusions

In conclusion, RFA is a useful, valuable, minimally invasive treatment option for residual thyroid nodule post-thyroidectomy, especially for small, isolated lesions. Further research and trials are needed to establish the applicability and long-term effectiveness of the RFA.

Acknowledgments

Funding: None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://jovs.amegroups.com/article/view/10.21037/jovs-24-32/rc

Peer Review File: Available at https://jovs.amegroups.com/article/view/10.21037/jovs-24-32/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jovs.amegroups.com/article/view/10.21037/jovs-24-32/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for the publication of this case report and the video. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Shah JP, Loree TR, Dharker D, et al. Prognostic factors in differentiated carcinoma of the thyroid gland. Am J Surg 1992;164:658-61. [Crossref] [PubMed]
2. Haugen BR. 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer: What is new and what has changed? Cancer 2017;123:372-81. [Crossref] [PubMed]
3. Durante C, Montesano T, Attard M, et al. Long-term surveillance of papillary thyroid cancer patients who do not undergo postoperative radioiodine remnant ablation: is there a role for serum thyroglobulin measurement? J Clin Endocrinol Metab 2012;97:2748-53. [Crossref] [PubMed]
4. Na DG, Lee JH, Jung SL, et al. Korean Society of Radiology (2012).
5. Haugen BR, Sawka AM, Alexander EK, et al. American Thyroid Association Guidelines on the Management of Thyroid Nodules and Differentiated Thyroid Cancer Task Force Review and Recommendation on the Proposed Renaming of Encapsulated Follicular Variant Papillary Thyroid Carcinoma Without Invasion to Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features. Thyroid 2017;27:481-3. [Crossref] [PubMed]
6. Zhang M, Tufano RP, Russell JO, et al. Ultrasound-Guided Radiofrequency Ablation Versus Surgery for Low-Risk Papillary Thyroid Microcarcinoma: Results of Over 5 Years' Follow-Up. Thyroid 2020;30:408-17. [Crossref] [PubMed]
7. Chen WC, Chou CK, Chang YH, et al. Efficacy of radiofrequency ablation for metastatic papillary thyroid cancer with and without initial biochemical complete status. Front Endocrinol (Lausanne) 2022;13:933931. [Crossref] [PubMed]