Computed Tomography Findings of Complete Branchial Cleft Fistula

Branchial cleft anomalies are embryonic remnants of the branchial arches and are described as the second most common congenital neck mass. Depending on their extent, these anomalies are classified as a cyst, sinus, or fistula with branchial cysts being the most common. Branchial cysts deriving from the second branchial arch are by far the most common, accounting for approximately 95% of all cases. Complete second branch arch fistulas with both an internal and external opening are a rare variant of this anomaly, and even less have been well-documented on computed tomography (CT) imaging in the literature. We present here a case of a 20-year-old female with CT findings consistent with a complete second branchial arch fistula extending from the tonsillar fossa to the external lateral neck.