A 44-year-old female patient attended a medical appointment due to a lump she had recently noticed in the upper third of her neck, on the right. At clinical examination, a firm, painless and pulsatile mass was felt in this area. It could be moved more easily side-to-side than up and down. Besides, it was observed a bulge in the right lateral wall of her oropharynx extending to the midline.

Figure 1: Neck ultrasonography – focus on the carotid space

Figure 2: Neck ultrasonography – focus on the carotid space

Figure 3: Computed tomography of the neck - after injecting contrast

Figure 4: Computed tomography of the neck - three-dimensional reconstruction

Question:
Based on the clinical data and imaging studies, which is the most likely diagnosis?