Revisiting Rupture of Benign Thyroid Nodules after Radiofrequency Ablation: Various Types and Imaging Features

Abstract

Background: To evaluate the imaging features, clinical manifestations, and prognosis of patients with thyroid nodule rupture after radiofrequency ablation (RFA).

Methods: The records of 12 patients who experienced thyroid nodule rupture after RFA at four Korean thyroid centers between March 2010 and July 2017 were retrospectively reviewed. Clinical data evaluated included baseline patient characteristics, treatment methods, initial presenting symptoms, imaging features, treatment, and prognosis.

Results: The most common symptoms of post-RFA nodule rupture were sudden neck bulging and pain. Based on imaging features, the localization of nodule rupture was classified into three types: anterior, posterolateral, and medial types. The anterior type is the most often, followed by posterolateral and medial type. Eight patients recovered completely after conservative treatment. Four patients who did not improve with conservative management required invasive procedures, including incision and drainage or aspiration.

Conclusion: Thyroid nodule rupture after RFA can be classified into three types based on its localization: anterior, posterolateral, and medial types. Because majority of thyroid nodule ruptures after RFA can be managed conservatively, familiarity with these imaging features is essential in avoiding unnecessary imaging workup or invasive procedures.

Keywords: Complication; Radiofrequency ablation; Safety; Thyroid nodule; Ultrasonography.

Fig. 1. (A) A 67-year-old man, who presented with a bulging neck mass, had been treated with radiofrequency ablation (RFA) due to a predominantly solid thyroid nodule at right thyroid gland. He had sudden bulging and pain on the right side of his neck 80 days after the RFA. (B, C, D) Computed tomography (CT) and (E, F) ultrasound show volume expansion and discontinuity of the anterior thyroid capsule with nodule content extended to the anterior extra-thyroidal area (arrows) (anterior type). (D) Intra-nodular hyper-attenuating portions on pre-contrast CT represent intra-nodular bleeding. (G) The patient was managed with fluid aspiration and intravenous antibiotics, and the lesion gradually regressed.

Fig. 2. (A) A 24-year-old woman, who presented with a bulging neck mass, had been treated with radiofrequency ablation (RFA) due to a predominantly solid thyroid nodule at right thyroid gland. (B) One month after RFA, the nodule decreased in size. However, at 156 days after RFA, the patient complained of neck pain and bulging. (C) Ultrasound shows a heterogeneous echoic lesion around the thyroid capsule (arrows) (posterolateral type). She was treated with compression and observation. (D) After a month, the lesion was completely disappeared.

Fig. 3. (A) A 42-year-old female, who presented with bulging neck mass, had been treated with radiofrequency ablation (RFA) due to a predominantly solid thyroid nodule at right thyroid gland. She complained of cough, neck discomfort and mild fever 65 days after RFA. (B, C) On computed tomography (CT) scan, the ablated nodule bulges to medial side and protrudes into the tracheal lumen (arrows) (medial type). (D, E) After conservative management with antibiotics, the lesion was completely disappeared on follow-up CT and ultrasound after 2 months.