Figure Legends
Fig. 1. Two different routes of pyriform sinus fistula (PSF). Route a. passing inside the inferior horn of the thyroid cartilage implies 4th pouch origin, while route b. running outside the horn indicates 3rd pouch origin. This difference in pathways affected the severity of clinical presentation.
Fig. 2. Accompanying tissues around the PSF in Cases 1, 2, and 8. These PSFs had parathyroid and thymic tissues so these were regarded as having 3rd pouch origin.
Fig. 3. Extrathyroid tissue beside the fistula in Case 8, indicated as having 3rd pouch origin.