Clinical anatomic study on the segment and adjacent of tract of congenital pyriform sinus fistula

Objective To investigate the anatomic tract of congenital pyriform sinus fistula (CPSF). Methods A total of 90 patients with CPSF undergoing open surgery between August, 2007 and March, 2017 at the Department of Guangdong General Hospital were retrospectively analyzed. Results The tracts of all the fistulas actually walked far different from those of theoretical ones. A whole fistula may be divided into 4 segments according to adjacent anatomy of CPSF. The posterior inner segment to the thyroid cartilage was initial part of the fistula. It originated from the apex of pyriform sinus, then piercing out of the inferior constrictor of pharynx inferiorly near the inferior cornu of the thyroid cartilage (ICTC), and descended between the lateral branch of the superior laryngeal nerve and the recurrent laryngeal nerve. The ICTC segment was the second part of the fistula, firstly piercing out of the inferior constrictor of pharynx and/or cricothyroid muscle, and then entering into the upper pole of thyroid. The relationship between fistula and ICTC could be divided into three types: type A (medial inferior to ICTC) accounting for 42.2% (38/90); type B (penetrate ICTC) for 3.3% (3/90); and type C (lateral inferior to ICTC) for 54.5% (49/90). The internal segment in thyroid gland was the third part of fistula, walking into the thyroid gland and terminating at its upper pole (92.2%, 83/90) or deep cervical fascia near the upper pole of thyroid (7.8%, 7/90). The lateral inferior segment to thyroid gland was the last part of the fisula, most of which are iatrogenic pseudo fistula, and started from the lateral margin of thyroid gland. Conclusions CPSF has a complicated pathway. Recognition of the tract and adjacent anatomy of CPSF will facilitate the dissection and resection of CPSF in open surgery. Key words: Congenital abnormalities; Congenital pyriform sinus fistula; Anatomy