A lateral cervical sinus, also known as a second pharyngeal or branchial cleft fistula/sinus, occurs when the second pharyngeal arch fails to grow caudally over the third and fourth arches, leaving remnants of the second branchial clefts in contact with the surface of the neck via a narrow canal. This type of sinus is detected on the lateral aspect of the neck directly anterior to the sternocleidomastoid muscle. We report two pediatric cases with lateral cervical sinus, and pathognomonic sonographic findings to confirm the diagnosis. The first case involved a 3-month-old boy with a sinus on the lateral neck and occasional drainage from a cervical sinus opening. Sonography revealed that the sinus tract extended between the external and internal carotid arteries. In case two, a 1-month-old girl presented with a sinus on the lateral neck and signs of acute infection at the site of a pinpoint opening. Sonography revealed an oval-shaped cystic lesion and sinus tract extending between the external and internal carotid arteries. Sonography does not require radiation or sedation for children. The best choice for the first examination for lateral cervical sinus is sonography, rather than CT, MRI, or contrast fistulograms.
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