These are lumps found in the front of the neck in the midline. They are formed due to a persistent thyroglossal duct.

During the development of the thyroid gland before birth, the thyroid gland in the foetus migrates from the bottom of the tongue to its final position in the neck. The path that the thyroid gland takes during its descent into the neck usually disappears, but sometimes persists as a persistent thyroglossal duct.

This persistent duct can give rise to cysts (fluid-filled lumps) or sinuses (blind-ending tracts that lead to the skin).