Review Question - QID 107917

The clinical presentation is most likely a thyroglossal duct cyst that originates from the migration of the primordial thyroid gland during embryologic development.

The child in this clinical scenario presents with an asymptomatic visible, palpable, soft, midline neck mass (Figure A) that moves with tongue protrusion. The appearance and description of its movements is classic for a thyroglossal duct cyst, which is an embryological remnant. The correct diagnosis for these masses can often times be obtained from history and physical alone.

Girard et al. describe that in the third week of life, the thyroid gland originates in the midline at the floor of the pharynx and later at the border between the anterior two-thirds and posterior one-third of the tongue. The primordial thyroid tissue then descends with the hyoid bone and normally will migrate to the anterioinferior border of the hyoid. On the seventh week of gestation, the thyroid gland is at its final location and the thyroglossal duct involutes. If there are any areas of incomplete involution, a midline cyst or fistula may develop. If the entire thyroglossal duct does not involute and remains patent, a thyroglossal duct cyst may develop because the duct itself is composed of secretory epithelium.

Meier et al. states that neck masses in children are seldom malignant, and one study demonstrated that only 11% of biopsied neck masses in children were cancerous. Pediatric neck masses tend to fall into three groups: developmental, inflammatory/reactive, and neoplastic. A mass since birth is usually benign and developmental such as vascular malformations or hemangiomas. In contrast, a quickly appearing mass may be inflammatory. Neoplastic masses tend to enlarge over months to years, which include lipomas, fibromas or neurofibromas.

Figure A is a clinical photograph of a thyroglossal duct cyst that presents as a palpable, soft, midline neck mass that moves with tongue protrusion. Illustration A demonstrates clues in the history and physical that are suggestive of certain diagnoses.

Incorrect Answers:
Answer 1: Patients with a history of recent infection may present with neck lymphadenopathy. It can be tender, sometimes bilateral if there is a systemic infection such as an upper respiratory infection or unilateral such as the case with Bartonella henselae, also known as cat scratch disease.
Answer 2: Neck trauma can present as a neck mass particularly if there is an underlying hematoma, which can resolve and fibrose over time. Alternatively, trauma may lead to a pseudoaneurysm with vascular injury. There is no indication of trauma or pulsatile masses in this case.
Answer 3: Malignancy is an uncommon diagnosis for pediatric neck masses. Suspicion may be high if the mass is rapidly expanding, hard, fixed and irregular.
Answer 5: Lymphoma can present as a neck mass. However, lymphoma does not typically present as a midline neck mass.