Right-sided pyriform sinus fistula: a case report and review of the literature.

Objectives. Pyriform sinus fistulae arise from disturbances in the development of the fetal third and fourth branchial pouches and are predominantly found on the left side. We report the rare case of a right-sided pyriform sinus fistula presenting as a lateral neck abscess. Study Design. Case report. Methods. A 24-year-old woman presented with a two-week history of right-sided neck abscess. A fluoroscopic sinogram revealed a fistulous tract extending from the abscess to the apex of the right pyriform sinus. It was determined that the fistula was likely a third or fourth branchial remnant, a rare right-sided finding. Chemocauterization of the fistulous tract with 40% trichloroacetic acid was used to successfully treat the patient. Results. Approximately 93-97% of branchial pouch anomalies are left sided. Treatment options include surgical excision and cauterization. Conclusions. Branchial cleft cyst and pyriform sinus fistula must be considered in the diagnosis of cervical abscess in either side of the neck.