Piriform sinus fistula and the ultimobranchial body

Abstract

Piriform sinus fistulae are an underlying abnormality common in patients with acute suppurative thyroiditis. The fistulae arise from the hypopharynx, and end in or adjacent to the thyroid lobe. These congenital fistulae seem to be remnants of one of the pharyngeal pouches in embryonic development, but their exact origin is still controversial. Resected specimens of the thyroid glands and fistulae from 15 patients were examined immunohistochemically with rabbit antisera to human calcitonin and thyroglobulin. The fistulae were lined by squamous, columnar or ciliated epithelium, and sometimes formed branches in the thyroid lobe. Near the branches solid cell nests existed. Mucous glands, follicular structures and thymic tissue were found in the fistula. The follicular structures stained for thyroglobulin. Immunostaining for calcitonin revealed aggregates of many C cells in the thyroid near the fistula. A few calcitonin-positive cells were also found in the fistula. These findings, along with the anatomical relation of the fistulae to major structures of the neck, strongly suggest that the fistulae are remnants related to the ultimobranchial body, and that the fistulae trace the migration route of the ultimobranchial body to the thyroid gland.

Fourth Branchial Fistula: Revisited

“…A further proof would have been if by immunohistochemistry we were able to demonstrate ultimobranchial body. 3 The presentation in all our cases has been similar as reported in the literature namely recurrent neck abscess. The presentation of the fistula at a slightly older age may be due to increase in swallowing pressure as the child's food quality changes to adult solid food.…”

A Case of Second Branchial Cleft Sinus with Double Opening from the Tonsil

“…In contrast, the crystal violet-stained tract clearly arose from the left pyriform sinus, penetrated the muscles, ran between the cricoid cartilage and the inferior horn of the thyroid cartilage, and terminated near the upper portion of the left lobe of the thyroid. The pathway was considered to be a typical fistula derived from the ultimobranchial body, a finding similar to one previously reported [3,8]. The tract also formed the internal lumen covered with the epithelium for full length in a pathological finding.…”

“…The fistula has been believed to be a remnant related to the third or fourth pharyngeal pouches that were present during embryonic development. Miyauchi et al [3] stated that the fistula was a remnant related to the ultimobranchial body. However, the precise origin of the internal fistula remains controversial.…”

Telomerase expression and proliferative activity suggest a stem cell role for thyroid solid cell nests

“…27 The unusual association of solid cell nests with thymic, [28][29][30][31] parathyroid, 28,29 adipose, 1,30 fibrous, 32 cartilaginous, 1,32 and salivary gland-type tissues 32 has been documented, and together with the production of mucins 1,28,33,34 reinforces the endodermal, ultimobranchial body origin of solid cell nests. The topographic distribution of solid cell nests in the thyroid gland, their association with C cells and different tissues related to branchial structures, and the presence of solid cell nests in some piriform sinus fistula (which are also considered as remnants related to the ultimobranchial body) 35 further support the existence of a relationship between solid cell nests and the ultimobranchial body. To the best of our knowledge, the presence of neural fibers in relation with solid cell nests has not been previously reported.…”