(A205) Anomalous Innominate Artery in Thyroidectomy: A Cautionary Tale

Introduction: High-riding innominate artery results from a persistent proximal segment of the fourth aortic arch causing the artery’s superior translocation, reported as high as the second tracheal ring. We present a case of a high-riding innominate artery found during thyroidectomy at the first tracheal ring.

Methods: We report a case of a 71-year-old female with multiple left thyroid nodules who presented to the otolaryngology clinic following FNA results revealing oncocytic follicular neoplasm and elected to undergo left hemithyroidectomy due to question of malignancy. Pre-operatively, a high-riding innominate artery anterior to the thyroid gland was noted on CT imaging of the neck, previously obtained for unrelated reasons. During the case, the artery was found overlying the first tracheal ring displacing the right thyroid lobe posteriorly and laterally. The artery was retracted safely out of the surgical field allowing for successful left hemithyroidectomy.

Results: Final pathology showed Hurthle cell carcinoma with encapsulated Papillary carcinoma. Given this diagnosis, completion thyroidectomy was recommended but poses a higher risk due to the aberrant innominate artery’s proximity to the remaining right thyroid lobe.

Conclusions: This case highlights the importance of considering aberrant innominate artery anatomy during thyroidectomy. Its proximity to the thyroid gland and position over the anterior tracheal wall poses risk of inadvertent arterial injury. Consideration of this abnormality is imperative in thyroid surgery and presents a challenge, and possibly a relative contraindication for other anterior neck surgery such as tracheotomy. With careful palpation, review of available imaging, and maintaining awareness of aberrant arteries, surgeons can better anticipate challenging anterior neck surgeries. This can reduce the risk of inadvertent, and possibly catastrophic intraoperative arterial injury.