Percutaneous Catheter Drainage with Polidocanol Sclerotherapy: A Novel Salvage Therapy for a Giant Recurrent Thyroid Cyst After Failed Radiofrequency Ablation

Background: Giant benign thyroid cysts (>5cm) are challenging; thermal ablation (RFA) often fails, and sclerotherapy is hampered by inflammatory exudate. We report a dual-mechanism salvage therapy for a giant cyst that recurred rapidly after failed RFA. Case Presentation: A 59-year-old female presented with dyspnea from a 7x6x5 cm cyst recurring two weeks post-RFA. She underwent ultrasound-guided aspiration (100 mL) and 3% polidocanol foam sclerotherapy. A soft catheter was left in situ for four days on negative pressure drainage, evacuating an additional 138 mL of inflammatory exudate. The patient experienced immediate symptom resolution, with near-complete fibrotic resolution at one-year follow-up. Conclusions: The combination of polidocanol sclerotherapy with prolonged catheter drainage is a highly effective, safe salvage therapy. This dual-mechanism approach ensures chemical ablation and prevents exudate reaccumulation, maximizing wall apposition for durable fibrosis and rapid symptom relief. It represents a potent option for giant thyroid cysts.