A healthy 12-year-old girl presented with a 4-year history of an enlarging anterior midline neck mass. She denied any other relevant signs or symptoms. There was no history of trauma. The mass was especially noticeable when the patient was speaking and moved with swallowing. Palpation revealed a midline, nontender, soft, cystic mass measuring approximately 2 × 2 cm anterior to the hyoid bone, without associated skin changes. Further examination, including fiberoptic laryngoscopy, demonstrated no abnormalities. A computed tomogram of the head and neck showed a 2.1 × 2.3 × 2.0-cm, hypoattenuating, well-circumscribed, simple cystic mass without enhancement anterior to the hyoid bone (Figure 1 and Figure 2). No surrounding changes or abnormalities were noted, and the findings of laboratory studies were normal.