Ultrasonographic characteristics of thyroid nodule rupture after microwave ablation: Three case reports.

RATIONALE Thyroid nodule rupture is a rare complication after microwave ablation (MWA). The ultrasonographic characteristics, clinical course, treatment, or prognosis of thyroid nodule rupture after ablation have not been systematically summarized. Three cases with thyroid nodule rupture after MWA were reported in this study, including the characteristic ultrasound images before ablation and after rupture. Meanwhile, we investigated the etiology, diagnosis, treatment and prevention of the rupture. These findings can provide references for the future clinical practice. PATIENTS CONCERNS All 3 patients were pathologically diagnosed as benign thyroid nodules by core needle biopsy and then received 1 session of MWA. DIAGNOSES Fourteen days to 1 month after MWA later, all 3 patients presented with abrupt neck pain and swelling, and 1 of them had a fever. Ultrasound examinations shared common features that the rupture of thyroid capsule and a soft-tissue mass with unclear margin in front of the thyroid gland, which connected with the post-ablation nodule. Three patients were diagnosed as thyroid nodule ruptures. INTERVENTIONS All 3 patients received conservative management after the ruptures. With the treatment of intravenous antibiotics for 1 week, the neck swelling of patients 1 and 2 both disappeared. The aggravation of neck swelling was found in patient 3. Ultrasonography of the neck revealed irregular fluid echo in the soft-tissue mass, suggesting abscess formation. Aspiration and irrigation were performed. The neck swelling regressed gradually over another 2 weeks with the treatment of antibiotics. Two months after ablation, ultrasound examination showed that the mass had completely disappeared. OUTCOMES None of the 3 patients underwent open surgery due to thyroid nodule rupture. At 1-year follow-up, the volume reduction rate of thyroid nodules in 3 patients were as follows: 100%, 98.1% and 90.7%. LESSONS Nodule rupture is a rare but severe complication after MWA of the thyroid nodules. The diagnosis can be confirmed by clinical symptoms and ultrasound examination, and most nodule ruptures could be cured with conservative treatment. Grasping the characteristics of ultrasound imaging during the course of disease, and dynamically assessing course of disease progression by ultrasonography could avoid unnecessary imaging examinations or invasive procedures.