Diagnosis of pyriform sinus fistula in children via ultrasonography.

A pyriform sinus fistula is a rare congenital abnormality of the third or fourth branchial pouch that usually affects children. We report one case of the condition; ultrasound (US) imaged a heterogeneous mass with a hypoechoic area and air bubbles representing an abscess. Although these manifestations are rare, prominent and characteristic findings on US may facilitate the diagnosis of pyriform sinus fistula.