Figure 1. Ultrasound of the left thyroid lobe.
Figure 2. Barium esophagram. Arrow indicates a left-sided pyriform sinus fistula.
Figure 3. Operative view. Surgical exposure (left); arrow demonstrates probe introduced into pyriform sinus. Endoscopic view (right); probe coming through pyriform sinus.
Pyriform sinus fistula is a rare condition. There is usually a history of repeated upper respiratory tract infection, pain, and tenderness of the thyroid.1 Although the entire thyroid may become firm and tender, the focus of inflammation is usually located in the left lobe.1 If suppuration occurs, the overlying skin becomes erythematous and warm.1 Considerable airway compression is uncommon, but hoarseness and odynophagia is seen.1
Fistulae arise from the apex of the pyriform sinus of the hypopharynx and end in or adjacent to the upper pole of the thyroid lobe2,3; thus, these cases can present as acute thyroiditis or as an anterior cervical abscess. The exact origins of the fistula are controversial,2,3 but suggested origins include the third pharyngeal pouch,4- 7 fourth branchial arch or pouch,8- 10 or the ultimobranchial body.11 Growth of the ultimobranchial body is often restricted or absent on the right side in the lower vertebrates, including reptiles.11,12 These findings might elucidate the left-sided predominance of the fistula. Findings from barium esophagram may identify the fistulous tract5,13- 17; however, it may fail to do so during the acute inflammatory phase, and studies should be repeated 6 to 8 weeks later.1
A pyriform sinus fistula should be considered in the presence of unilateral (mostly left-sided) thyroiditis (not necessarily suppurative) and recurrent left anterior cervical abscesses. Recurrence is the rule unless complete excision of the fistulous tract is performed.
Accepted for publication October 20, 1998.
Reprints: Juan Bass, MD, FRCSC, Department of Surgery, Children's Hospital of Eastern Ontario, 401 Smyth Rd, Ottawa, Ontario K1H 8L1, Canada (e-mail: email@example.com).
Radiological Case of the Month. Arch Pediatr Adolesc Med. 2000;154(5):523-524. doi: