Fourth branchial cleft cyst and congenital absence of the contralateral thyroid lobe

AbstractFourth branchial cleft anomalies are the rarest type of branchial anomalies. They arise from an incomplete involution of the fourth branchial cleft during development. We report the successful surgical excision of a left fourth branchial cleft cyst in a pediatric patient presenting with an enlarging painless lateral neck mass. Intraoperatively the patient was found to have a large left branchial cleft cyst, which displaced the left superior pole of the thyroid lobe. In addition, there was hemiagenesis of the right thyroid.