Case series of de novo occurrence of Graves' disease following thermal ablation for benign thyroid nodules: an uncommon event that should be considered.

Introduction: Thermal ablation (TA), including radiofrequency (RFA) and microwave ablation (MWA), is a widely used, minimally invasive alternative to surgery for benign thyroid nodules. While transient, self-limited thyrotoxicosis is a recognized effect of the procedure, the onset of Graves' disease (GD) post-TA remains exceedingly rare and poorly characterized. Case reports: We report three cases of new-onset GD occurring 3-10 months after RFA or MWA, identified among more than 500 patients treated at our tertiary care Endocrinology Unit. All patients were female and had undergone TA for cytologically benign nodules. Two had a documented history of thyroid autoimmunity. At diagnosis, all three exhibited suppressed TSH, elevated thyroid hormone levels, and positive anti-TSH receptor antibodies (TRAb). None had been tested for TRAb before treatment. One case occurred during pregnancy and was managed with propylthiouracil; the others received antithyroid treatment with methimazole. Conclusion: Although rare, GD may develop following TA, likely through immune activation triggered by thyroid tissue injury in genetically predisposed individuals. Routine TRAb screening before TA is not currently justified; however, clinical awareness is essential to distinguish transient post-ablation thyrotoxicosis from true GD and to ensure timely initiation of antithyroid therapy when appropriate. Despite these rare cases, the overall incidence remains very low, confirming the excellent safety profile of TA for benign thyroid nodules.