Neck masses can originate from a congenital anatomic anomaly, infection, or neoplasm. Congenital anomalies consist of branchial and thyroglossal duct cysts and failed thymic descents. In the embryo, branchial cysts arise from the thymic stalk or the pharyngeal pouch and can be present at birth or develop later. They lie beneath the sternocleidomastoid muscle and can bulge out from its anterior border. The branchial cysts can become infected and enlarge to the extent that they compress the airway or upper esophagus. Thyroglossal duct cysts are spherical, midline masses that can extend back to the base of the tongue and represent all of the neonate's thyroid tissue. In the embryo, the thymus gland arises high in the neck and descends into the anterior mediastinum. If there is any interruption of this caudal movement, the thymus can appear as a soft, compressible mass anywhere along the anterior border of the sternocleidomastoid muscle.

Infectious masses can be due to tuberculosis, Epstein-Barr viral infection, cellulitic facial infections (Ludwig angina), and subacute regional lymphadenitis (cat scratch disease). Noninfectious causes include Kawasaki disease, sarcoidosis, Rosai-Dorfman disease, and histiocytic necrotizing lymphadenitis.

Neoplastic masses in the cervical region can be teratomas, hemangiomas, neurofibromas, lymphomas, goiters, or cystic hygromas. Teratomas are firm, midline masses arising adjacent to the thyroid isthmus. Hemangiomas may be extensive, consequently compressing vital structures. Neurofibromas may arise individually or as a consequence of neurofibromatosis (von Recklinghausen disease) and can be very large. Goiters are enlarged thyroid glands that present as a hypothyroid, hyperthyroid, or euthyroid state. Ultrasound, CT, and MRI are the imaging modalities used most often to determine the nature of a neonatal neck mass.

References

• Levine MC, Arroyo A, Likourezos A, Homel P, Dickman E. The use of point of care ultrasound in the evaluation of pediatric soft tissue neck masses. Am J Emerg Med. 2019;37:1466-1469.
• Thorell EA. Cervical lympadenitis and neck infections. In: Long SS, Prober CG, Fischer M, eds. Principles and Practice of Pediatric infectious Diseases. 6th ed. Elsevier; 2023:142-153.