Two-year-old with a persistent fetal vein presenting as a neck mass

Benign lesions that present as neck masses are relatively common findings i n the pediatric otolaryngology practice. The differential diagnosis include s persistent fetal structures, such as thyroglossal duct and branchial clef t remnants, as well as vascular malformations, such as hemangiomas and arte riovenous malformations. Persistent fetal vascular structures, however, are less common. We describe a 2-year-old boy who presented with a mass in the anterior aspect of his neck that was determined to be a persistent anomalo us fetal vein. We also discuss the embryology and development of the venous system in the neck, as well as the options for the diagnosis and managemen t of benign vascular lesions that present as neck masses in the pediatric p atient.