Histological analysis
Two independent investigators (KS and KO) observed pathological
hematoxylin-eosin staining samples under the microscope in 12 of 19
cases. Immunohistochemical staining of calcitonin was conducted in 2 of
12 cases, while no positive case was found. The pattern of the
epithelium, structure of the wall, and contents in the lumen of the
fistula were evaluated. Moreover, the characteristics of inflammation
cells and thyroid, thymic, and parathyroid tissues around the fistula
were also analyzed.