Oncocytic (Hürthle Cell) Carcinoma Invading the Innominate Vein: A Case Report

Oncocytic (Hürthle cell) carcinoma is a rare subtype of differentiated thyroid carcinoma associated with increased vascular invasion, distant metastasis, and reduced responsiveness to radioactive iodine (RAI) therapy compared with other thyroid malignancies. Direct invasion of major mediastinal vessels, including the brachiocephalic (innominate) vein, is exceedingly rare and presents significant diagnostic and operative challenges. We report the case of a 71-year-old male who presented with progressive dysphagia and an enlarging multinodular goiter. Initial fine-needle aspiration was benign; however, worsening compressive symptoms prompted left thyroid lobectomy, which demonstrated widely invasive oncocytic carcinoma with extensive angioinvasion (pT3a). Completion thyroidectomy with central neck dissection revealed tumor invasion of the left internal jugular and middle thyroid veins, requiring ligation. Despite adjuvant RAI therapy, serum thyroglobulin (Tg) levels progressively increased. Subsequent positron emission tomography and computed tomography demonstrated a fluorodeoxyglucose (FDG)-avid thrombus and associated venous aneurysm involving the left brachiocephalic vein. The patient underwent successful resection via trapdoor thoracotomy with en bloc excision of the involved venous segment. Pathology confirmed metastatic oncocytic carcinoma with negative margins. This case highlights the importance of vigilant biochemical surveillance, advanced imaging, and aggressive multidisciplinary management in selected patients with oncocytic thyroid carcinoma involving the great vessels.