A man in his 50s presented to the emergency department with sudden onset of left-sided neck swelling, pain, and progressive respiratory distress that started while playing basketball. He reported a 2-day history of left-sided jaw pain preceding the swelling but had no other clinically significant history. Physical examination showed trismus, rightward tracheal deviation, and a hoarse voice. The left side of his neck was diffusely swollen without palpable fluctuance, induration, or a discrete mass. A complete blood cell count revealed no abnormalities. A contrast-enhanced computed tomographic (CT) scan of the neck showed a large hyperdense mass interposed between the left common carotid artery and the hypopharynx (Figure , A-C). There was resultant lateral deviation of the left common carotid artery and medial deviation on the supraglottic larynx and hypopharynx, resulting in airway compromise. Of note, the density of the mass was identical to that of the adjacent vasculature. There was extensive edema surrounding the primary abnormality. Additional findings include periapical dental abscesses in 2 teeth (Figure , D).