Uncommon Cause of Mass in the Neck—Giant Common Carotid Artery Aneurysm

Significance Statement

The presence of a large pseudoaneurysm in the common carotid artery is a very rare condition. Pseudoaneurysms are often associated with trauma, infection, inflammation, and vasculopathy. We have identified this condition, whose association with calcium metabolism disorder is very unusual.

Introduction

Common carotid artery (CCA) aneurysms are defined as a localized diameter increase of more than 50%. ¹ These aneurysms are uncommon. The most common location for them is at the level of the CCA bifurcation.^1,2

The most common etiology of true aneurysms is atherosclerosis. Atherosclerotic aneurysms are usually fusiform and located at the carotid bifurcation. The most common etiology of pseudo-aneurysms is endarterectomy and trauma. Other causes include infections (tuberculosis, syphilis, fungal), connective tissue diseases (Marfan, Ehler-Danlos), inflammatory diseases (Takayasu, Behçet’s), and radiation to the neck region.

Some patients with CCA aneurysms are asymptomatic and are detected incidentally.² The most common reason for the presentation of symptomatic patients is swelling in the neck. Other reasons include autophagy, dysphagia, hoarseness, Horner syndrome, tinnitus, bleeding because of an aneurysm rupture, and ischemic attacks because of thrombus. ³

When CCA aneurysms are detected, they should be treated because of the high risk of embolism and rupture. Although surgical treatment is more commonly used for treatment, endovascular stenting may be preferred for aneurysms in a high location.

Case Presentation

A 55-year-old woman who had had a mass on her neck for 6 years was admitted to our hospital. She had been a chronic kidney patient for 9 years and was undergoing dialysis. Upon ultrasonographic examination, a saccular-shaped, partially thrombosed aneurysmatic lesion was observed at the level of the right CCA bifurcation. A further examination was performed by computed tomography (CT) angiography. A carotid CT angiography showed a lesion compatible with a partially thrombosed pseudoaneurysm sac approximately 34 × 50 × 60 mm in size distal to the right CCA in the anterior just proximal to the bifurcation level (Figure 1). In addition, images of widespread sclerosis in bone structures and widespread lytic destructive lesions on the background of sclerosis were observed.

Figure 1.

Post-contrast consecutive axial (A and B) and coronal (C) CT angiography and coronal anteroposterior projection volume rendering three dimensional (D) CT angiography image demonstrate a partial thrombosed giant CCA aneurysm (star). CT, computed tomography; CCA, common carotid artery.

Conclusion

Sometimes, patients with CCA aneurysms may present with long-standing swelling in the neck (as our patient did). These lesions may mimic solid neck masses. Since CCA aneurysms can rupture or embolize to the brain from thrombosed aneurysms, prompt diagnosis and treatment are crucial. Imaging techniques should establish a definitive diagnosis and differentiate the aneurysm from other carotid lesions, especially carotid body tumors, before surgical planning. Although magnetic resonance (MR) angiography and CT angiography are used in the diagnosis of CCA aneurysms, CT angiography is more commonly used because it is faster and more accessible.

Carotid artery pseudoaneurysm is clinically similar to neck neoplasms such as nerve sheath tumor, carotid body tumor, and metastatic lymph node. ¹ Sectional imaging methods such as MR imaging, CT scan, and CT or MR angiography are frequently used diagnostic modalities in the preoperative differential diagnosis of these lesions.^4-7 On CT and MR angiography, while neck neoplasms such as carotid body tumor are well-demarcated masses appearing intense enhancement with smooth margin, pseudoaneurysms are contrast-filled vascular lesions.^4,5 The external carotid artery aneurysm associated with carotid body tumor has been reported as an extremely rare condition in medical literature. ⁷ Being aware of this unusual association is essential to avoid accidental injury to vascular structures during neck dissection for tumor.

Patients with chronic renal failure and end-stage renal disease are prone to arterial hypertension and hyperlipidemia.^8,9 Atherosclerosis-related vascular complications have been reported to be significantly higher in these subjects. ¹⁰ In a study using high-resolution duplex ultrasonography, Rossi et al. ¹⁰ reported that prevalence of carotid artery lesions was higher in patients with chronic renal failure than in the control subjects. The researcher found severe vascular pathologies in some patients. Patients with chronic renal failure have higher fibrinogen level than in control subjects. ¹⁰ High fibrinogen levels are an important independent risk factor for atherosclerosis and cerebrovascular complications. We hypothesize that carotid artery pseudoaneurysm in our patient could be associated with intimal damage secondary to high blood pressure, hyperlipidemia, and hyperfibrinogenemia.