First, the cyst is lined by non-keratinized stratified squamous epithelium, similar to oropharyngeal epithelium. Also, the cyst wall contains numerous primitive epithelial ducts that merge into areas with normal-appearing thyroid follicles. It is probable that pieces of grass, reaching the oropharynx of the lamb, migrated down the thyroglossal duct, resulting in an abscess. They are lined by multi-layered epithelium that often forms follicles filled with eosinophilic colloid. If any portion of the thyroglossal duct remains patent after birth, a cyst may form, often not becoming clinically evident for several months.
Neoplastic transformation occurs uncommonly, resulting in papillary carcinoma.
Thyroglossal duct cysts must be differentiated from other midline pharyngeal pouch cysts such as parathyroid cysts, branchial cysts, ultimobranchial duct cysts, follicular cysts, and salivary mucoceles. The endocrine glands. The embryologic origin of thyroglossal duct cysts. Six hens were submitted live for necropsy examination. Three birds had multiple small, white foci in the liver, kidney, and ovary, respectively.