Radiology Quiz Case

Abstract

A 29-YEAR-OLD WHITE MAN PRESENTED WITH a 12-month history of a left-sided cervical mass. He was asymptomatic and denied having pain, dysphagia, dyspnea, or cough. Physical examination revealed a nontender, nonpulsating, hard, fixed mass measuring 3 6 cm in diameter in the high jugular region. Oropharyngeal examination revealed bulging and medial displacement of the pharynx and left tonsil, without trismus or visible mucosal lesions. No cranial nerve deficits or Horner sign was noted. Findings of the rest of the examination of the nasopharynx, hypopharynx, and larynx were noncontributory. An axial computed tomographic scan demonstrated a nonenhancing well-circumscribed left parapharyngeal mass (Figure 1, black asterisk) laterally displacing the internal and external carotid arteries (Figure 1, short and long black arrows, respectively) and clearly separated from the parotid gland by the posterior belly of the digastric muscle (Figure 1, white arrow). A coronal view of a T1-weighted magnetic resonance image revealed an oval mass (Figure 2, asterisk) involving the left parapharyngeal space, without skull base extension. Magnetic resonance angiography (MRA) with gadolinium showed splaying of the left internal and external carotid arteries (Figure 3, arrows) by a hypovascular mass (Figure 3, asterisk). A smooth, encapsulated mass separated from the carotid sheath, displacing both the external and internal carotid arteries anteriorly and the internal jugular vein posteriorly, was observed during surgery. Cranial nerves IX through XII were identified and preserved. The mass extended from the cranial base down to the level of the second tracheal ring. It was completely excised and sent for pathologic examination. At the end of the operation, the hypoglossal nerve responded poorly to electrical stimulation, although it was anatomically preserved. The postoperative period was uneventful, and 6 months later, the patient was free of recurrence but manifested a Horner sign. What is your diagnosis?