First Branchial Cleft Cyst Confined to the Pinna.

First branchial cleft cysts (FBCCs) arise due to an incomplete fusion of the cleft between the first and second branchial arches. Classically, they are found inferior to the pinna or along the external auditory canal. This report presents a unique case of a nine-month-old male with a first branchial cleft cyst completely within the pinna. The patient presented with a left auricular pit and pinna mass. Ultrasound revealed a homogeneous hypoechoic mass isolated to the pinna. Surgical resection revealed the cyst to be anterior to the inferior pinna cartilage, with the tract projecting anteriorly and inferiorly. Final pathology revealed a benign cyst lined by squamous epithelium and a rim of cartilage, confirming an FBCC. To our knowledge, FBCCs isolated to the pinna have not been previously reported. Awareness of the various presentations of this rare anomaly is essential for a prompt and accurate diagnosis.