Horner syndrome after ethanol ablation for radioactive iodine therapy refractory papillary thyroid carcinoma.

Papillary thyroid carcinoma (PTC) is the most prevalent form of thyroid malignancy. Although it carries a favorable prognosis, especially for individuals under the age of 45, tumor recurrences in the thyroid bed still occur. In fact, recurrence rates are observed in approximately 20% of patients following initial treatment. For patients who are not candidates for surgery or radioactive iodine therapy, ethanol ablation is a treatment option for recurrences in the thyroid bed and lymph node metastases. This case report details a 31-year-old female patient with a PTC who underwent total thyroidectomy and radioactive iodine therapy. One year later, a locoregional recurrence developed in the thyroid bed. The recurrence was determined to be iodine-refractory, and due to its size and the patient's preference, surgery was not an option; hence ethanol ablation was performed. After the ethanol ablation procedure, the patient exhibited left eyelid drooping. She was diagnosed with Horner syndrome characterized by left upper eyelid ptosis, myosis, and anhidrosis. Although uncommon, Horner syndrome should still be considered as a potential postoperative complication in patients undergoing ethanol ablation for locoregional recurrence of PTC.