Fistula of the fourth branchial pouch.

Most of the congenital anomalies of the branchial apparatus are from the second arch, pouch, and cleft; some are from the first and third arches. Fourth branchial pouch remnants are very rare. We present a rare case of fourth branchial fistula, with characteristic clinical features of recurrent left-sided neck abscess that burst spontaneously, forming a fistula. Diagnosis of fourth branchial pouch fistula was confirmed by contrast radiography (ie, fistulogram and barium swallow) revealing the internal opening in the apex of the left pyriform fossa.