Novel approach of thyroid radiofrequency ablation for huge nodules-Eggshell technique (evenly margin-preserving ablation): a case report.

Background: Radiofrequency ablation (RFA) for huge thyroid nodules often requires multiple sessions to achieve long-term efficacy. We present our experience with a stepwise approach utilizing a nodule margin-preserving ablation, termed the Eggshell technique, in the treatment of a thyroid nodule exceeding 9 cm in diameter. Case Description: A 44-year-old woman presented with compressive symptoms due to a large left thyroid solid nodule measuring 5.81 cm × 3.19 cm × 9.26 cm, with a volume of 90.84 mL. Cytopathology, including core needle biopsy, confirmed Bethesda Category II in two separate evaluations. RFA was performed under local anesthesia using the Eggshell technique, which preserved the nodule margin while ablating the internal tissue. The procedure lasted 83 minutes, delivering a total energy of 38.59 kJ. At 6 months, the nodule volume decreased to 29.75 mL [volume reduction ratio (VRR) 67.25%]. After three additional sessions, the volume further reduced to 1.59 mL (VRR 98.25%) at 42 months. The patient experienced minimal pain (pain score 1), with no hemorrhage, post-ablation edema, or nodule rupture. Serial ultrasonography allowed precise visualization of residual tissue, optimizing the timing of subsequent ablations. Conclusions: This case suggests that the Eggshell technique, an evenly margin-preserving RFA strategy, may be a valuable option for managing huge thyroid nodules that inevitably require multiple sessions. By minimizing patient discomfort and complications, and facilitating decision-making during follow-up, this approach can complement conventional RFA techniques for large nodules.