Around the sixth week of gestation, the thyroid gland begins a short migration. It forms at the base of the tongue and travels down the front of the neck to its final position, trailing behind it a narrow tube called the thyroglossal duct. That duct is supposed to disintegrate and disappear by about the tenth week.
Often it does not. And in a case report published this month, titled "Mediastinal thyroglossal duct cyst after thyroidectomy mimicking recurrent thyroid disease," radiologists C.D. Strange, R. Agrawal, D.M. Palacio, and M.T. Truong describe a remnant of that vanished duct showing up not in the neck, where it belongs, but inside the chest, in a patient whose thyroid had already been surgically removed.
