Thyroid ultrasonography (US) is a fundamental part of thyroid nodule evaluation. US is an effective and non-invasive method for evaluating the thyroid gland in real-time and at a relatively low cost.¹⁾ A few case reports have described an esophageal abnormality being misinterpreted as thyroid nodules.^2,3) At the same time, a normal esophagus was also reported to be misdiagnosed as a thyroid nodule with microcalcifications.⁴⁾ These studies show the ability to visualize the esophagus using the US and emphasize the importance of careful evaluation and visualization during routine thyroid US to prevent misdiagnosis. US may also be useful for visualizing the compressed esophagus by culprit thyroid nodules, but insufficient evidence supports its use to date.

Thyroid radiofrequency ablation (RFA) is a low-risk, effective, and minimally invasive procedure with an acceptable safety profile to treat benign thyroid nodules.⁵⁾ RFA helps to reduce cosmetic concerns from scarring and compressive symptoms, including dysphagia and pain, by significantly decreasing thyroid nodule volume.⁶⁾ Traditionally, surgery is considered the first-line therapy for most patients with symptomatic thyroid nodules, either total thyroidectomy or lobectomy.⁷⁾ Although surgery can provide immediate relief of compressive symptoms due to thyroid nodule(s), it has associated complications, not limited to a painful procedure, neck scar, risk of infection, and risk of postoperative hemorrhage but also the risk of recurrent laryngeal nerve damage during the procedure, postoperative hypocalcemia secondary to hypoparathyroidism and postoperative hypothyroidism requiring lifelong levothyroxine in case of total thyroidectomy.^8,9) A study by Bernardi et al.¹⁰⁾ showed no significant difference in patient satisfaction after surgery versus RFA in benign non-functioning thyroid nodules.

In this case series, we describe four patients who presented with dysphagia, diagnosed to be due to esophageal compression by thyroid US and treated by thyroid RFA with subsequent improvement or resolution of the dysphagia.

This is a case series of four patients who presented to an academic endocrinology practice for the evaluation and management of thyroid nodule(s). Inclusion criteria included patients who presented with dysphagia that was diagnosed to be due to esophageal compression caused by thyroid nodule(s) and the acceptance to proceed with thyroid RFA to treat these nodules. Otherwise, patients were excluded. IRB approval for this retrospective case series was obtained.

These patients had dysphagia, which they described feeling in the lower neck area. Assessment of the thyroid nodule(s) and the esophagus was performed using point-of-care US NextGen LOGIQ e^Ⓡ (General Electric, Boston, MA, USA) or Sonosite M-Turbo^Ⓡ (FUJIFILM Sonosite, Washington, WA, USA). Relevant images were collected during the evaluation and stored securely in the utilized electronic health record. Thyroid RFA was performed with VIVA Combo RFA Generator^Ⓡ (TaeWoong Medical USA, Los Angeles, CA, USA) and Star RFA Electrode^Ⓡ (TaeWoong Medical USA, Los Angeles). At least, two benign biopsies were obtained before RFA. The thyroid US exams, assessment of esophageal compression, and the RFA procedures were performed by the principal investigator, who is ECNU-certified (Endocrine Certification in Neck Ultrasound). Nodule volume was calculated as (length×width×height×π)/6. The data presented here represent the assessments before the procedure and at the one-month follow-up visit after the RFA procedure.

All the patients were asked to assess the thyroid nodule-related symptoms score on a scale of 0-10 (no symptoms of dysphagia at 0 and severe dysphagia at 10).¹¹⁾ Cosmetic scores were assessed on a scale of 1 to 4, ranging from non-palpable nodules to cosmetically apparent nodules on inspection.¹¹⁾ Symptoms and cosmetic scores were reported for all the cases and are the commonly used assessment tools in most thyroid nodules and RFA-related studies.

Case 1

A 53-year-old woman was seen in our endocrine clinic for non-toxic multinodular goiter and primary aldosteronism. She was initially found to have thyroid nodules incidentally on a CT scan. Thyroid US followed by fine needle aspiration biopsies (FNA) of two nodules were benign. The patient reported dysphagia to both solids and liquids, hoarseness of voice, and positional shortness of breath for about 18 years. EGD was performed, which showed reflux with no evidence of compression, but medications did not help her dysphagia. Repeat FNA of the two nodules three years later confirmed they were benign. On her US, she had notable compression of the esophagus by the left thyroid nodule. RFA of the left thyroid nodule was performed afterward with interval resolution of her dysphagia within a few days after the procedure, and the nodule volume reduction is shown in Table 1. There was interval improvement of the esophageal compression on US exam, as shown in Fig. 1.

In our case series, we utilized thyroid US to visualize the esophagus posterior to the thyroid gland, both before and after the RFA, as shown in Fig. 1. Neck US has been utilized to confirm nasogastric tube placement and esophageal foreign body visualization but not to evaluate the esophageal compression by thyroid nodule.^12,13) This case series favors using the thyroid US as a diagnostic tool for visualizing esophageal compression. Bedside thyroid US performed in thyroid practices is a readily available and cost-effective resource to evaluate the patients for compressive features in real-time during the evaluation of nodules. It reduces the cost and decreases the delay in establishing the diagnosis and formulating a management plan. There is little literature about using thyroid US to visualize esophageal compression by thyroid nodules. More studies need to be done to address this knowledge gap.

Thyroid RFA led to volume reduction in all patients along with either resolution or improvement of dysphagia, as shown by the symptoms scores and decrease of esophageal compression on the thyroid US. RFA has been utilized successfully in Asia and Europe for many years.¹⁴⁾ A study by Cervelli et al.,¹⁵⁾ which included 46 patients with benign thyroid nodules, showed RFA as a reliable and safe alternative to surgery. Che et al.¹⁶⁾ presented a study of 200 patients with nodular goiter who underwent surgery and 200 patients who underwent RFA. The study concluded that RFA should be considered first-line therapy for benign thyroid nodules, as it was as effective as surgery but with fewer complications and hospitalizations, and preservation of thyroid function. RFA has been shown to be effective in clinically significant volume reduction of benign thyroid nodules with persistent results over several years.¹⁷⁾ Two benign biopsies are necessary before RFA to ensure the benign nature of compressive nodules, and one can suffice if a benign appearance is noted.^18,19) This is important to decrease the risk of false negative initial biopsy. The four abovementioned patients had two confirmed benign biopsies before RFA.

In conclusion, thyroid US can allow visualization of esophageal compression by thyroid nodules and relief after therapy. RFA is a minimally invasive and effective tool in treating symptomatic thyroid nodules.

The authors would like to thank Dr. Erik Imel, professor of adult and pediatric medicine at Indiana University School of Medicine; Dr. Cary Mariash, professor of medicine at Indiana University School of Medicine; and Dr. James Walsh, associate professor of medicine at Indiana University School of Medicine for reviewing the manuscript and providing valuable input.

No potential conflict of interest relevant to this article was reported.