Enhancing Skull Base Structure Along the Carotid Sheath in a Patient With Oropharyngeal Squamous Cell Carcinoma | Head and Neck Cancer | JN Learning | AMA Ed Hub [Skip to Content]
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Enhancing Skull Base Structure Along the Carotid Sheath in a Patient With Oropharyngeal Squamous Cell Carcinoma

Educational Objective
Based on this clinical scenario and the accompanying image, understand how to arrive at a correct diagnosis.
1 Credit CME

A 62-year-old man with a prior 10–pack-year history of smoking presented with a 3-cm right level IIa lymph node. Fine-needle aspiration results showed metastatic p16-positive squamous cell carcinoma. No mucosal primary site was identified with positron emission tomography, computed tomography, or a head and neck examination. The patient underwent direct laryngoscopy with directed biopsies and bilateral tonsillectomy. Pathology results revealed a 1.8-cm primary cancer in the right tonsil, and the patient received a stage designation of T1 N1 M0. The tumor was intracapsular, and all surgical margins were negative. Multidisciplinary tumor board discussion concluded that surgical and nonsurgical treatment options were available, and the patient elected to proceed with further surgery, which would entail additional directed biopsies at the primary site with additional resection if necessary and selective neck dissection of levels Ib to IV. In preparation for the neck dissection, computed tomography of the neck with contrast was obtained. Imaging results revealed an enhancing structure at the skull base adjacent to the carotid sheath (Figure).

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D. Persistent hypoglossal artery

Anatomical variations of the internal carotid artery (ICA) are reported in 5% to 6% of the general population. The typical location of the ICA is posterolateral to the pharyngeal wall and 2.5 cm from the pharyngeal constrictor muscles at the tonsillar fossa.1 Certain anatomic variations of the carotid artery may place the vessel closer to the pharyngeal wall, thereby increasing the risk of injury during surgical procedures. In addition, recognized vascular anomalies in the form of persistent embryologic connections can present a similar surgical challenge.

During embryologic development, the primitive forebrain is vascularized through the carotid system. Four embryologic anastomoses complete this connection and include the trigeminal, hypoglossal, acoustic, and proatlantal arteries.2,3 These anastomoses regress with the development of the posterior communicating and vertebral artery system.2,3 These anastomotic connections generally do not persist past fetal life, resulting in the typical anatomy of an ICA without branches in the neck. Persistence of these embryonic vascular structures is typically accompanied by a hypoplastic or absent vertebrobasilar system.2,3

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Article Information

Corresponding Author: Stephen Y. Kang, MD, James Cancer Hospital and Solove Research Institute, Department of Otolaryngology–Head & Neck Surgery, The Ohio State University Wexner Medical Center, 460 W 10th Ave, Columbus, OH 43210 (stephen.kang@osumc.edu).

Published Online: August 20, 2020. doi:10.1001/jamaoto.2020.2260

Conflict of Interest Disclosures: None reported.

Additional Contributions: We thank the patient for granting permission to publish this information.

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