Abstract
RATIONALE: Ethanol ablation (EA) is recommended as the primary treatment for benign thyroid cysts and its use is increasing. Although complications, such as pain, hoarseness, and hematoma, have been reported after EA, implantation of benign thyroid tissue has not been previously reported. Here, we present a case of intranodal implantation of benign thyroid tissue as a late complication of EA. PATIENT CONCERNS: A 46-year-old man underwent EA for a benign cystic nodule in the left thyroid lobe and developed a thyroid abscess after several days. The patient was treated with incision and drainage and was discharged without complications. Two years later, the patient presented with multiple masses in both cervical regions. Ultrasound (US) and computed tomography indicated metastatic papillary thyroid carcinoma (PTC) at bilateral levels III, IV, and VI. The results of US-guided fine-needle aspiration cytology (FNAC) indicated benign lesions; however, thyroglobulin levels in the needle washout fluid were >250,000 ng/mL. DIAGNOSIS: Total thyroidectomy with neck dissection was performed to remove the thyroid and lymph node masses and confirm the diagnosis. Histopathological findings revealed multiple areas of benign thyroid tissue in the bilateral cervical lymph nodes, with no indication of metastatic PTC, even after a BRAF gene mutation study and immunohistochemical staining for HBME-1 and galectin-3. OUTCOMES: No recurrence or complications were observed during the follow-up for 29 months. LESSONS: Complicated EA may be associated with the dissemination of benign thyroid tissue into lymph nodes, with a confusing clinical presentation mimicking metastatic PTC. Radiologists and thyroid surgeons should consider the risk of intranodal implantation of benign thyroid tissue as a late complication of EA.