Congenital Aortic Arch Malformation Presenting as Bilateral Pulsatile Neck Mass: A Unique Case Report

Abstract

ABSTRACT

Vascular malformations of the aortic arch and its main branches such as cervical aortic arch and high‐riding brachiocephalic artery can present as pulsatile neck swelling. Although this entity is rare, an initial Doppler ultrasound is suggested before intervention to avoid complications from unidentified aberrant vessels.

Abbreviations

• BSA
• brachiocephalic artery
• CAA
• cervical aortic arch
• CT
• computed tomography
• MRI
• magnetic resonance imaging
• SCA
• subclavian artery
• VSD
• ventricular septal defect

Introduction

Cervical aortic arch (CAA) is a rare congenital anomaly where a redundant aortic arch is located high in the neck at or above the level of the clavicles [1, 2]. This condition is rare, with an incidence of less than 1 in 10,000 live births, and is most common in young women [2, 3]. The pathogenesis involves abnormal development or involution of the fourth and third primitive aortic arches [4]. 22q11 deletion with or without conotruncal abnormalities has also been reported [4]. CAAs are usually asymptomatic but can present as pulsatile neck masses or with respiratory and esophageal compression symptoms, especially when associated with complete vascular rings [1]. A high-riding brachiocephalic artery (BCA) reaching far superiorly in the neck at the fourth cervical vertebrae is also rare with few cases reported in the literature [5].

Cross-sectional computed tomography (CT) angiography or magnetic resonance (MR) angiography imaging is preferred for diagnosis, with three-dimensional (3D) volume-rendered images providing improved visualization [2]. Medical treatment with control of cardiovascular risk factors and a follow-up ultrasound (US) is indicated in uncomplicated cases. Aortic aneurysm, dissection, compression symptoms, or vascular rings require surgical management [1, 6–8]. Here we report a unique case of complex vascular anomaly of aortic arch vessels not reported before. The case presents interesting embryology teaching points and adds to the evolving classification scheme of aortic arch malformations.

Case History

A 13-year-old female presented to our hospital with bilateral pulsatile neck swelling since birth and palpitations for a year. On physical examination, she appeared healthy; her blood pressure was 124/90 mmHg, and her pulse rate was 74 beats per minute, with comparable peripheral pulse strength and no radial-radial or radial-femoral delay. There was a 4 × 3 cm pulsatile, non-tender neck mass on the left side anterior to the sternocleidomastoid muscle with bruits over it but no overlying skin changes. A similar lesion was also observed on the right side. The patient has no pertinent past self or family medical history.

Methods

With a clinical impression of a bilateral carotid body tumor to rule out bilateral common carotid artery aneurysm, imaging studies were requested. On the initial Doppler US, there were two major arteries coursing rostrally. When we followed these vessels high in the neck, the right-side artery appeared to be BCA and the left ascending aorta. The right internal and external carotid arteries arose separately from the BCA which arched backward, descended to the thoracic inlet, and continued as the subclavian artery (SCA) (Figure 1). The vertebral arteries branched out normally from the SCA. On the left side, the ascending aorta rose high into the neck, forming an arch. The distal extent of this vessel was difficult to access, and the left SCA branched out from the descending part deep in the thorax. Echocardiography showed a restrictive type of membranous ventricular septal defect (VSD) and a normal tricuspid aortic valve.

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A post-contrast neck and chest CT scan confirmed our Doppler ultrasound findings with the ascending aorta arising from the left ventricle. The BCA branched from the ascending aorta at the third thoracic vertebra (T3) level (Figure 2) and ascended to the level of the fourth and fifth cervical vertebrae (C4/C5) to give the internal and external carotid arteries separately with no common carotid artery. The distal segment continued as the SCA descended back to the thoracic inlet. On the left side, the internal and external carotid arteries arose from the ascending aorta separately, and the aortic arch extended high into the neck posterolateral to the larynx at the level of the third cervical vertebra (C3) and then coursed inferiorly. The descending aorta continues down on the ipsilateral side and has a normal anatomy throughout its visualized course (Figure 2). The left SCA arose from the descending aorta at the second thoracic vertebra level (T2). There was no evidence of aneurysmal dilatation of the aorta or its major branches or complete vascular rings. The trachea was central. We did not include CT 3D images because they have suboptimal quality due to delayed image acquisition.

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Conclusion and Results

Our patient is currently asymptomatic. She is on a follow-up to monitor symptoms related to compression of surrounding anatomical structures.

Discussion

CAA is an arch extending beyond the medial end of the clavicle and is often seen on the right side [2]. Clinically, it is mostly asymptomatic, with some cases presenting with a pulsatile neck mass or symptoms associated with tracheal or esophageal compression such as dyspnea or dysphagia, recurrent infections, or complications such as aneurysm formation and dissection [9–11]. Proposed embryogenesis of this anomaly includes regression of the fourth aortic arch with a persistent third aortic arch, failure of normal caudal descent of a normally developed aortic arch, and persistence of both the third and fourth aortic arches forming a confluence [6, 7]. CAA usually occurs in isolation, but associations with cardiac anomalies, DiGeorge syndrome, Turner's syndrome, and deletions of chromosome 22q11.2 have been documented. Congenital cardiac abnormalities associated with left CAA include VSDs, tetralogy of Fallot, and patent ductus arteriosus [5].

The branching pattern in CAA is very complex. Haughton et al. described five distinct types based on arch-sidedness, descending aortic laterality, and branching order of the BCA [4, 6, 7]. Type A has a right arch with separate origin of the external and internal carotid arteries from the aortic arch. Type B is similar to type A but has dual common carotid arteries. Type C has a left cervical arch with a right descending aorta and a single common carotid trunk. Type D is a left cervical arch with a normal branching pattern, redundant transverse aorta, and left descending aorta. Type E is a right CAA with a right descending aorta and an aberrant left SCA [6].

Our case is similar to type D as there was a left CAA with an ipsilateral descending aorta. However, the branching pattern of the arteries we found was bizarre, with separate origins of the internal and external carotid arteries bilaterally, no common carotid artery, and a right-side high-riding BCA. In their review of 54 previously reported cases, Zhang and colleagues found that 7 (13%) of the CAA cases could not be classified using the above classification and proposed a new scheme that is also said to be more intuitive in surgical decision-making [1]. Our case is close to Zhang's A1 classification based on major vessel branching and laterality. Although this updated classification still does not capture the minimal variation observed, we are uncertain about its significance for patient management [1, 10, 11]. A double CAA has separate external carotid, internal carotid, and SCAs arising from each arch and presents clinically with bilateral pulsatile neck masses [6]. However, the literature has not reported a case like ours with left CAA and right high-riding BCA with abnormal branching patterns of carotid arteries on both sides.

BCA is the first and largest branch of the aortic convexity and branches into the right common carotid artery and SCA behind the right sternoclavicular joint [6, 8]. It develops from the aortic sac and the proximal right fourth aortic arch. The persistence of a portion of a proximal segment of the right fourth aortic arch is said to result in a high-riding BCA [9, 10]. This explains associations with CAA as both involve abnormal involution or development of the fourth aortic arch [8, 10]. A high-riding BCA was previously defined regarding tracheal rings, while Cai et al. recently proposed an objective criterion of 2 cm above the suprasternal notch [5]. A case in which BCA rises to the level of the fourth cervical vertebra is rare and usually found during neck surgery [6, 8–10].

The differential diagnosis for a pulsatile neck mass can be separated into vascular and more common non-vascular causes and Doppler color flow imaging is useful in the initial evaluation [6]. Anomalous vessels at the base of the neck include a high-riding BCA, tortuous carotid artery, cervical origin of right SCA, CAA, and venous anomalies such as dilatation of internal or external jugular veins [7, 8]. Echocardiography, MRI, and CT angiography are the main modalities to detect and evaluate CAA and aberrant aortic arch vessels. CT allows detailed anatomy visualization with reformation in multiple planes or three-dimensional (3D) imaging helpful to characterize relations with adjacent structures while MRI allows assessment without radiation exposure [8].

Congenital variants and anomalies of the aortic arch are important to recognize, although most neck swellings have thyroid or lymph node origins [8]. There are reports of cases where CAA was mistakenly diagnosed as an aneurysm and ligated, resulting in the death of the patient, and a case where it was confused for cervical lymphadenopathy and almost aspirated [6]. This suggests that a lack of proper identification of this entity can lead to an erroneous diagnosis and improper treatment, with serious consequences. Our patient is asymptomatic and is on regular follow-up for symptoms related to the compression of surrounding anatomical structures. CAA is prone to premature atherosclerosis and aneurysm formation, highlighting the importance of adequate cardiovascular risk factor management [9].

Author Contributions

Tesfahunegn Feleke: conceptualization, methodology, writing – original draft, writing – review and editing. Gelebo Gedeno: conceptualization, writing – original draft. Daniel Zewdneh Solomon: supervision, writing – review and editing. Samuel Sisay Hailu: conceptualization, supervision, writing – original draft, writing – review and editing.

Ethics Statement

The authors have nothing to report.

Consent

Written informed consent was obtained from the patient's parents for anonymized patient information to be published in this article.

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

The data supporting the findings of the case are available upon request to the corresponding author.

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