A 43-year-old woman, who was pointed out a tumor in the anterior cervical region at a mass screening, was diagnosed as having a thyroid tumor with calcification and underwent surgery. During surgery, a restiform matter continuing to the inferior horn of thyroid cartilage from the thyroid tumor was found. It was diagnosed as piriform sinus fistula. As much of the restiform matter as possible was separated with ligation from the oral side, and extracted along with the tumor. After surgery, an esophageal transillumination demonstrated no apparent fistula.
Piriform sinus fistula is a disease which usually presents with a cervical abscess during childhood. To the best of our knowledge, this case in which the fistula had been asymptomatic and was detected in adulthood is the first one in Japan. When a restiform matter continuing from a thyroid tumor is uncovered, as was observed in this case, the possibility of this disease should always be considered. It is considered necessary to ensure the closure of the fistula in order to prevent a cervical abscess after surgery.